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Australian dingoes are definitive host of Neospora caninum
Abstract
To provide objective data on the potential role of dingoes (Canis lupus dingo) in the life cycle of Neospora caninum in Australia, the production of N. caninum oocysts by experimentally infected canids was investigated. Three dingo pups raised in captivity and three domestic dogs were fed tissue from calves infected with an Australian isolate of N. caninum, Nc-Nowra. Oocysts of N. caninum, confirmed by species-specific PCR, were shed in low numbers by one dingo pup at 12-14 days p.i. The remaining animals did not shed oocysts. Furthermore, the blood from two out of three dingoes tested positive for DNA of N. caninum using PCR tests at 14 and 28 days p.i. Oocyst shedding from the intestinal tract of a dingo demonstrates that dingoes are definitive hosts of N. caninum and horizontal transmission of N. caninum from dingoes to farm animals and wildlife may occur in Australia.
Supplementary resources (8)
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... Prior to 2010, domestic dogs were the only confirmed definitive host of N. caninum in Australia (King et al., 2010). Even so, evidence implicating domestic dogs' involvement in transmission of N. caninum was inconsistent, mostly due to the lack of evidence for the temporal association in the seroconversion of domestic dogs with abortion storms in cattle. ...
... Even so, evidence implicating domestic dogs' involvement in transmission of N. caninum was inconsistent, mostly due to the lack of evidence for the temporal association in the seroconversion of domestic dogs with abortion storms in cattle. In fact, serologically negative dogs on infected cattle farms have been a common occurrence (Barber et al., 1997;King et al., 2010;Reichel, 2000). Nevertheless, it is important to note that the results of serological studies do not discriminate between past and current infections of N. caninum, and the sensitivity and specificity of some of the assays used are contentious (Donahoe et al., 2015). ...
... It is important to note that the prevalence of N. caninum infection is likely to be greater than that reported in this study as the probability of collecting a faecal sample while the host is shedding infective oocysts is low. While the rate of shedding infective oocysts in dingoes has yet to be determined, in domestic dogs, the shedding rate varies from a few days to several weeks (Cavalcante et al., 2011;Dubey et al., 2007), and is estimated to be similar in other canids (Gondim, 2006;Gondim et al., 2004;King et al., 2010). Moreover, previous studies found differences in the number of oocysts excreted in dogs and coyotes after experimental infection with 10,000 and 250 oocysts excreted per day, respectively (Gondim et al., 2002(Gondim et al., , 2004. ...
Infection with Neospora caninum parasites is a leading cause of reproduction losses in cattle worldwide. In Australia, this loss is estimated to total AU$110 million every year. However, despite this considerable economic impact, the transmission cycle and the host(s) responsible for the sylvatic transmission of the parasite remain to be defined. Dingoes (Canis familiaris) have been suggested to be a wildlife host of N. caninum in Australia, but this is yet to be proven in a non-experimental setting. This study aimed to determine the prevalence of natural N. caninum shedding in Australian wild dogs (defined as dingoes, dingo-domestic dog hybrids and feral dogs) by performing molecular analysis of faecal samples collected in wild dog populations in south-east Australia. Molecular analysis allowed host species identification and dingo purity testing, while genetic analysis of Coccidia and Neospora conserved genes allowed for parasite identification. Among the 115 samples collected and determined to belong to dingoes, dingo-domestic dog hybrids and foxes, Coccidian parasites were detected in 41 samples and N. caninum was identified in one sample of canine origin from South East Australia (Mansfield). Across all samples collected in Mansfield only 15 individuals were successfully identified by genotype. Thereby our study determined that 6.7% (1/15, 95% confidence intervals 1.2 – 29.9) of wild dogs were actively shedding N. caninum oocysts at this site. Further, only four individuals were identified at a second site (Swift Creek), and none were positive. This study conclusively confirms the role of wild dogs in the horizontal transmission of N. caninum parasites in Australia.
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... N. caninum has a complex facultative heteroxenous life cycle with canids such as domestic and wild dogs (Canis familiaris) (McAllister et al., 1998), grey wolves (Canis lupus) (Dubey et al., 2011b), coyotes (Canis latrans) (Gondim et al., 2004) and dingoes (Canis lupus dingo) (King et al., 2010) confirmed as definitive hosts in which sexual replication the parasite occurs (Donahoe et al., 2015;Dubey and Schares, 2011a). Ruminants, horses, rabbits and mice have been reported as intermediate hosts in which asexual replication takes place. ...
... Of these, cattle are the most frequently affected (Donahoe et al., 2015;Dubey et al., 2007b). Interestingly, dogs can also play the role of intermediate host in N. caninum life cycle (Dubey and Schares, 2011a;King et al., 2010). ...
... Canids can acquire infection by ingestion of the infected tissues from the intermediate hosts or of the sporulated oocysts from the environment, and/or by vertical transmission (Dijkstra et al., 2001;Gondim et al., 2002;Schares et al., 2001). Dogs have been shown to shed oocysts into the environment after ingestion of infected offal or placental membranes from infected cows (Donahoe et al., 2015;King et al., 2010), maintaining N. caninum life cycle. Neosporosis has emerged as a serious disease in cattle and dogs worldwide (Dubey and Schares, 2011a;Dubey et al., 2007b). ...
... N. caninum has a complex facultative heteroxenous life cycle with canids such as domestic and wild dogs (Canis familiaris) (McAllister et al., 1998), grey wolves (Canis lupus) (Dubey et al., 2011b), coyotes (Canis latrans) (Gondim et al., 2004) and dingoes (Canis lupus dingo) (King et al., 2010) confirmed as definitive hosts in which sexual replication the parasite occurs (Donahoe et al., 2015;Dubey and Schares, 2011a). Ruminants, horses, rabbits and mice have been reported as intermediate hosts in which asexual replication takes place. ...
... Of these, cattle are the most frequently affected (Donahoe et al., 2015;Dubey et al., 2007b). Interestingly, dogs can also play the role of intermediate host in N. caninum life cycle (Dubey and Schares, 2011a;King et al., 2010). ...
... Canids can acquire infection by ingestion of the infected tissues from the intermediate hosts or of the sporulated oocysts from the environment, and/or by vertical transmission (Dijkstra et al., 2001;Gondim et al., 2002;Schares et al., 2001). Dogs have been shown to shed oocysts into the environment after ingestion of infected offal or placental membranes from infected cows (Donahoe et al., 2015;King et al., 2010), maintaining N. caninum life cycle. Neosporosis has emerged as a serious disease in cattle and dogs worldwide (Dubey and Schares, 2011a;Dubey et al., 2007b). ...
Despite the importance of N. caninum in veterinary medicine, knowledge on the prevalence of this parasitosis in dogs is limited in some countries. The aim of this study was to assess the prevalence of N. caninum infection in stray dogs in Chalkidiki, Northern Greece. This prospective study was conducted between January 2018 and December 2019 in stray dogs aged ≥6 months old. Blood samples were collected by venipuncture before the female and male dogs underwent the spay and castration procedures, respectively. The indirect enzyme-linked immunosorbent assay (ELISA) was used to screen dogs for the presence of IgG antibodies against N. caninum. Of 511 dogs included in this study, 39 (7.63%) were positive for IgG antibodies against N. caninum. Of all the dogs, 221 were males and 290 females, with positive results for IgG antibodies found in 16 (7.24%) males and 23 (7.93%) females. Preventive measures should be developed and implemented to break the domestic cycle between dogs and bovine. We want to highlight the importance of regional reporting of N. caninum infection prevalence in dogs and control measures by veterinarians and veterinary authorities to farmers and public, in order to avoid this disease’s spread.
... Dogs are the primary definitive host for this parasite in which sexual replication occurs [10], and they may also be affected clinically [11,12]. Other canids may also act as definitive hosts in parts of the world [13,14]. ...
... The total of 17 publications included in this time period describe the seroprevalence of N. caninum infection in a number of species and countries; one study reported on the dingo (Canis lupus dingo), after the realisation a couple of years earlier that the dingo can also be a definitive host for N. caninum in Australia [14]. This study [65] found a high (27.0%) ...
... In the third examined time period (2006 to 2012), there was an increased interest in other possibly N. caninum affected species, such as wildlife, birds, small ruminant populations, as well as further research on prevalence studies around the world, enabling a better understanding of the prevalence and epidemiology (possible wildlife reservoirs, incl. the identification of the dingo in Australia as a definitive host species [14]) as well as a simulation of efficacious and economic control strategies. A better understanding of the parasite-cattle interaction led to experimental vaccines that were 100% efficacious [98]. ...
Background:
Neospora caninum has been recognised world-wide, first as a disease of dogs, then as an important cause of abortions in cattle for the past thirty years. Over that time period, there have been improvements in the diagnosis of infection and abortion, new tests have been developed and validated, and it is timely to review progress to date.
Methods:
Bibliometric methods were used to identify major trends and research topics present in the published literature on N. caninum. The tools used were SWIFT-Review, VOSviewer and SciMAT, along with the published papers found in the MEDLINE, Dimensions and Web of Science databases. A systematic review of the published Neospora literature (n = 2933) was also carried out via MEDLINE and systematically appraised for publications relevant to the pathogenesis, pathology and diagnosis of Neospora abortions.
Results:
A total of 92 publications were included in the final analysis and grouped into four main time periods. In these four different time periods, the main research themes were "dogs", "abortion", "seroprevalence" and "infection". Diagnostics, including PCR, dominated the first two time periods, with an increased focus on transmission and abortions, and its risk factors in cattle.
Conclusions:
Longitudinal analyses indicated that the main themes were consistently investigated over the last 30 years through a wide range of studies, with evolving emphasis initially on dogs and diagnostic test development, followed by application to cattle, the identification of the risk factors leading to abortion, and in the latter time periods, an understanding of the immunity and a search for vaccines.
... Nevertheless, it remains questionable which species within the wildlife population play a significant role as definitive or intermediate hosts. Grey wolves (Canis lupus), coyotes (Canis latrans) from North America [5,14] and Australian wild dogs (Canis lupus dingo) [15,16] were confirmed as definitive hosts, and their prevalence ranges from 2.2% to 10% [6,14]. Red foxes (Vulpes vulpes) were suggested as possible definitive hosts [17], but research results are more consistent with their role as intermediate hosts [18][19][20]. ...
... The confirmed definitive hosts of N. caninum in the sylvatic cycle are grey wolves [6], coyotes [14] and Australian wild dogs [15,16]. The reported seroprevalence in grey wolves ranged from 3.2% to 39.0% [42], while a study from the United States found a molecular prevalence of 4.1% in wolf feces [6]. ...
Neospora caninum is an obligate intracellular parasite that causes reproductive disorders and major economic losses in cattle, and induces neuromuscular disorders in canids. Exogenous infections are becoming increasingly important due to disease outbreaks. The sylvatic life cycle of N. caninum interferes with the domestic dog-ruminant life cycle, but understanding of it is scarce. The population of wild canids may play an important role in parasite dispersion. Feces from 42 grey wolves (Canis lupus) and 39 golden jackals (Canis aureus) were analyzed for the N. caninum Nc5 gene using a novel real-time PCR (qPCR) with a detection limit of 5 targets/µL in clinical samples. Three wolves (3/42; 7.1%) and one golden jackal (1/39; 2.6%) tested positive, which is the first detection of N. caninum in the population of grey wolves in Slovenia and the first detection of N. caninum DNA in the feces of a golden jackal. In addition to the grey wolf, we propose the golden jackal as a potential definitive host with hypothetical epidemiological importance for the sylvatic-domestic life cycle of N. caninum, due to its proximity to human habitats and its rapid expansion throughout Europe.
... Neospora caninum is an intracellular protozoan parasite with worldwide distribution, affecting domestic and wildlife species [1]. Domestic (dogs) and wild canids (coyotes, wolves, and dingoes) are the definitive hosts of N. caninum; they excrete oocysts and become infected by ingesting contaminated herbivores' tissues [2][3][4]. By contrast, ruminants are intermediate hosts that may become infected through consuming food or water contaminated with oocysts shed by definitive hosts (horizontal transmission) [4,5]. ...
... It is plausible that wild deer can become infected with N. caninum following ingestion of food or water contaminated with oocysts excreted by definite hosts such as domestic or wild dogs [3]. Indeed, active shedding of N. caninum oocysts in wild dogs (defined here as dingoes, feral domestic dogs and their hybrids) [31], as well as the report of antibodies in domestic dogs [32], have been confirmed in Australia. ...
Infections with the coccidian parasite Neospora caninum affect domestic and wild animals worldwide. In Australia, N. caninum infections cause considerable losses to the cattle industry with seroprevalence of 8.7% in beef and 10.9% in dairy cattle. Conversely, the role of wild animals, in maintaining the parasite cycle is also unclear. It is possible that native or introduced herbivorous species could be reservoir hosts of N. caninum in Australia, but to date, this has not been investigated. We report here the first large-scale screening of N. caninum antibodies in Australian wild deer, spanning three species (fallow, red and sambar deer). Consequently, we also assessed two commercial cELISA tests validated for detecting N. caninum in cattle for their ability to detect N. caninum antibodies in serum samples of wild deer. N. caninum antibodies were detected in 3.7% (7/189, 95% CI 1.8 – 7.45) of the wild deer serum samples collected in south-eastern Australia (n = 189), including 97 fallow deer (Dama dama), 14 red deer (Cervus elaphus), and 78 sambar deer (Rusa unicolor). Overall, our study provides the first detection of N. caninum antibodies in wild deer and quantifies deer's potential role in the sylvatic cycle of N. caninum.
Supplementary Information
The online version contains supplementary material available at 10.1186/s12917-023-03712-2.
... Felids (domestic and wild) are the only known definitive hosts of T. gondii, but the parasite infects almost all warm-blooded vertebrates, including human populations that act as the intermediate host. To date, only domestic dogs (Canis lupus familiaris), coyotes (Canis latrans), wolves (Canis lupus), and dingoes (Canis lupus dingo) have been identified as definitive hosts of N. caninum [5][6][7][8]. Furthermore, N. caninum infects a restricted range of intermediate hosts, including cattle (Bos taurus), sheep (Ovis aries), and probably other warm-blooded animals [6,[9][10][11][12][13]. ...
... To date, only domestic dogs (Canis lupus familiaris), coyotes (Canis latrans), wolves (Canis lupus), and dingoes (Canis lupus dingo) have been identified as definitive hosts of N. caninum [5][6][7][8]. Furthermore, N. caninum infects a restricted range of intermediate hosts, including cattle (Bos taurus), sheep (Ovis aries), and probably other warm-blooded animals [6,[9][10][11][12][13]. At present there is no evidence that N. caninum can successfully infect humans [14]. ...
Toxoplasma gondii and Neospora caninum are obligate intracellular protozoan parasites infecting a wide range of hosts worldwide. However, information on the epidemiology of toxoplasmosis and neosporosis in cats from Portugal is limited. Thus, this study aims to evaluate anti-T. gondii and anti-N. caninum seroprevalence in client-owned cats from Portugal and to identify risk factors using a panel of well-characterized sera. A total of 183 domestic cats were sampled and screened for antibodies against T. gondii and N. caninum using commercial ELISA assays, and their owners answered an online questionnaire designed to obtain background information. The overall anti-T. gondii and anti-N. caninum seroprevalences were 13.1% (CI: 8.97–18.77) and 3.8% (CI: 1.87–7.68), respectively. Univariate analysis revealed that living strictly indoors was a significant protection factor (cOR: 0.053; CI: 0.005–0.627), and the presence of a chronic disease a significant risk factor (cOR: 3.106; CI: 1.062–9.082) to T. gondii seroprevalence. When performing multivariate analysis, only chronic disease (aOR: 57.527; CI: 1.7–1976.7) and seropositivity to N. caninum (aOR: 7.929; CI:0.8–82.9) were found to be a significant risk factor to anti-T. gondii antibodies. To the best of our knowledge, this is the first report of N. caninum seropositivity in cats from Portugal.
... The disease is responsible for severe economic losses in the beef and dairy industries, mainly associated with poor reproductive performance of affected cattle, but also associated with reduced milk production, early slaughter and increased weight loss (Dubey 2003;Dubey and Schares 2011;Reichel et al. 2013). Until now, only domestic dogs (Canis familiais), Australian dingoes (Canis lupus dingo), coyotes (Canis latrans), and gray wolves (Canis lupus) are considered definitive hosts of the parasite (McAllister et al. 1998;Gondim et al. 2004;King et al. 2010;Dubey et al. 2011). Although serological positivity against N. caninum has been reported in several animal species, only a few are considered intermediate hosts (ruminants animals), including some mammalian and avian species (McAllister et al. 1998;Gondim et al. 2004;King et al. 2010;Dubey et al. 2011;Dubey and Schares 2011;de Barros et al. 2018). ...
... Until now, only domestic dogs (Canis familiais), Australian dingoes (Canis lupus dingo), coyotes (Canis latrans), and gray wolves (Canis lupus) are considered definitive hosts of the parasite (McAllister et al. 1998;Gondim et al. 2004;King et al. 2010;Dubey et al. 2011). Although serological positivity against N. caninum has been reported in several animal species, only a few are considered intermediate hosts (ruminants animals), including some mammalian and avian species (McAllister et al. 1998;Gondim et al. 2004;King et al. 2010;Dubey et al. 2011;Dubey and Schares 2011;de Barros et al. 2018). ...
Neospora caninum is recognized worldwide as one of the most important abortive pathogens in cattle. Although abortion cases are also recorded in sheep and goats, information and epidemiological data on neosporosis in goats are insufficient. In Türkiye, neosporosis in goats has been serologically detected in Adana, Antalya, Ankara, Burdur, Elazig, Erzurum, Kirsehir, Kirikkale, Kilis, Konya, Nigde, Sanliurfa, Ordu and Osmaniye provinces. To the best of our knowledge, there are no studies detecting N. caninum in goats living in Van province. For this reason, in this study, it was aimed to determine the seroprevalence of N. caninum in goats bred in Gevas district of Van. For this purpose, 368 sera were collected from goats of different ages and sexes from 15 villages of Gevas. A commercially cELISA was used to detect specific anti-N. caninum antibodies in the serum samples. Only one of the examined goats (0.27%) was seropositive for neosporosis. It was determined that the positive sample was over 4 years old and had abortion history. In conclusion, the presence and seroprevalence of N. caninum infection in the goat population in the Gevas region of Van province, a region where this protozoon has not been adequately investigated, was revealed for the first report with this study.
... infection in cattle and other intermediate hosts in other studies [18,19,22,23]. Since canids are defined as the definitive hosts of N. caninum [13,[24][25][26], we assume that horses living not only in stalls but also in paddocks or pasture are more likely to be in contact with oocysts shed by the definitive host and to be infected by horizontal transmission than horses living only in stalls. ...
... Most of the previous studies which evaluated the association between various risk factors and seropositivity only performed univariable statistical analysis [3,18,20,26]. Several factors were identified as significantly associated with Neospora seropositivity, most of them related to the management of the farm and the horses. These include routine use of anthelmintics [21], proximity to other animal species [19,20], feeding management [19,20], the use of horses [19] and quarantine [19]. ...
Equine Neospora infection has been linked to neurological disorders and infertility in horses. This study looked into the risk factors for infection and the exposure to Neospora spp. in horses. The study was performed in two independent populations in Israel. The first consisted of apparently healthy horses, and the second consisted of mares examined during pregnancy and after parturition. Sera samples collected from horses and mares were tested for Neospora exposure by the indirect fluorescent antibody test (IFAT). The study revealed seroprevalence of 24% in apparently healthy horses and 66.4% and 48.6% in mares during gestation and after parturition, respectively. Among the investigated risk factors, older age (p = 0.026) and housing in both stalls and paddocks (p = 0.033) in apparently healthy horses, and Arabian breeds (p = 0.005) in pregnant mares, were found to be significantly associated with Neospora spp. seropositivity in univariable, but not multivariable, statistical analysis. This study revealed high exposure of equines to Neospora parasites, especially mares. Horse farm management, in combination with active surveillance, including serological testing and follow up, could help reduce the spread of the parasite among horses in endemic areas.
... This protozoan also infects rodents, wild ungulates, birds, and marine mammals [4]. The parasite employs two hosts to complete its life cycle, so that dog (Canis familiaris) [5], dingo (Canis dingo) [6], coyote (Canis latrans) [7], and gray wolf (Canis lupus) [8] are definitive hosts, while cattle and buffalo are the most important intermediate hosts [9]. The parasite possesses three distinct infective stages, comprising tachyzoite (acute infection), bradyzoite (chronic infection), and sporozoite (environmental contamination) [10]. ...
... (c) Upon refinement, these parameters were improved to 90.2%, 8.8%, 0.5%, and 0.5%, respectively. 6 BioMed Research International parasite burden and induced specific antibody responses [58,59]. Mice vaccinated with a set of antigens such as NcGRA6, NcGRA7, NcMIC1, and NcSRS2 expressed in a bacterial vector (Brucella abortus) provided complete protection against acute disease [60]. ...
Vaccination is a standout preventive measure to combat neosporosis among cattle herds. The present in silico study was done to evaluate the physicochemical properties and potent immunogenic epitopes of N. caninum SRS2 protein as a possible vaccine candidate. Web-based tools were used to predict physicochemical properties, antigenicity, allergenicity, solubility, posttranslational modification (PTM) sites, transmembrane domains and signal peptide, and secondary and tertiary structures as well as intrinsically disordered regions, followed by identification and screening of potential linear and conformational B-cell epitopes and those peptides having affinity to bind mouse major histocompatibility complex (MHC) and cytotoxic T lymphocyte (CTL). The protein had 401 residues with a molecular weight of 42 kDa, representing aliphatic index of 69.35 (thermotolerant) and GRAVY score of -0.294 (hydrophilic). There were 53 PTM sites without a signal peptide in the sequence. Secondary structure comprised mostly by extended strand, followed by helices and coils. The Ramachandran plot of the refined model showed 90.2%, 8.8%, 0.5%, and 0.5% residues in the favored, additional allowed, generously allowed, and disallowed regions, correspondingly. Additionally, various potential B-cell (linear and conformational), CTL, and MHC-binding epitopes were predicted for N. caninum SRS2. These epitopes could be further utilized in the multiepitope vaccine constructs directed against neosporosis.
... N. caninum has a heteroxenous life cycle consisting of two distinct modes of reproduction: an asexual reproduction, which occurs in intermediate hosts such as sheep, goats, cattle and others [1,13,[16][17][18]; and a sexual reproduction, which only occurs in canids such as dogs (Canis lupus familiaris) [19][20][21], coyotes (Canis latrans) [22], wolfs (Canis lupus) [23,24] and dingoes (Canis lupus dingo) [25]. Canids are the definitive host for this parasite, and they may also be affected clinically [26][27][28][29]. ...
... In Italy, the prevalence of neosporosis and the relationship between N. caninum infections in dogs and cattle was analyzed with both serological and molecular methods [12,13,25,[48][49][50][51][52]. In Italy, as no official control plans for neosporosis have never been implemented, prevalence data can be mainly deduced from local studies [53]. ...
Neosporosis is recognized as one of the major causes of bovine abortion worldwide. Canids are the main definitive host for this parasite and the presence of dogs in the farm is an important factor for the Neospora caninum infection in bovines. Since, in the province of Lecce, located in the Apulia region of Southern Italy, there are no studies showing the presence of the infection in farm animals, the objective was to perform a serological evaluation for anti-N. caninumantibodiesin serum from 706 dairy cattle and 21 farm dogs located in 40 farms uniformlydistributed over the territory.The presence of N. caninum infection was confirmed in 90.0% (36/40) of the 40 farms examined. The results obtained on all serum samples by an enzyme-linked immunosorbent assay (ID Screen® Neospora caninum competition ELISA kit) for anti-N. caninumantibodies showed a seropositivity rate of 21.1% (149/706) among dairy cows, with a statistically significant higher percentage of positive subjects in the animals over two years old and a positivity rate of 42.9% (9/21) in tested dogs. The obtained data confirmed the presence of neosporosis even in the Lecce area, where it could therefore represent an important cause of abortion and economic losses.
... The parasite is a common cause of abortion in cattle with a significant economic impact in the dairy and beef industries (Trees et al., 1999). It was first reported as a parasite of the domesticated dogs (Canis familiaris) associated with encephalomyelitis and myositis (Bjerkas and Presthus, 1984), which are definitive hosts of the parasite, since a sexual phase occurs in the intestine of them , and oocysts are shed in their feces (McAllister et al., 1998;Gondim et al., 2004), and also other canids, such as Australian dingo (Canis lupus dingo) (King et al., 2010), the coyote (Canis latrans) (Gondim et al., 2004) and the gray wolf (Canis lupus) ( Dubey et al., 2011). ...
The aim of this study was conducted to estimate the prevalence of Neospora caninum infection in domesticated chickens by using the conventional molecular technique (PCR). A total 100 brain samples were examined by the target Nc-5 gene with an infection rate 6% (6/100). This study is the first molecular diagnosis of N. caninum in domesticated chickens in Iraq, and the results are highlight on the role of these animals in the maintain and spread the infection to canids in the environment.
... Several definitive hosts of N. caninum have been identified so far. It mostly includes the members of the Canidae family, among them the first to be recognized was the dog, followed by the coyote (Gondim et al., 2004), the Australian dingo (King et al., 2010), and the gray wolf . The parasite has also been found in warm-blooded, vertebrates acting as the intermediate hosts, such as: horses, sheep, goats, alpacas, llamas (Abo-Shehada and Abu-Halaweh, 2010), birds (Romero et al., 2016), water buffalo (Romero-Salas et al., 2017), pigs (Snak et al., 2019) and rodents (Medina-Esparza et al., 2013). ...
The objective of this study was to determine the seroprevalence of Neospora caninum, and the effect of associated risk factors in ten sheep production flocks in the state of Colima, Mexico. A total of 350 blood serum samples were collected, processed via the ELISA technique, and risk factors were calculated using logistic regression analysis. The overall prevalence was 13.14%, and 80% of the flocks had at least one positive animal, with a variation from 5.71 to 45.71%. Prevalence was higher in males (18.75%) than in females (12.87%), in purebred animals (13.87%) than in crossbreed animals (11.42%), and in sheep with body condition less than two. Water source, flock size, and the presence of animals other than canines constituted the main risk factors associated with the presence of the disease (P<0.05). In addition, animals raised under an extensive production system tend to present a higher prevalence, while the presence of dogs did not appear to be a risk factor. Animals raised in flocks in which the managers received technical assistance and had more schooling showed 4.12-and 4.15-times higher probability of contracting the disease respectively. The presence of N. caninum in sheep and risk factor identification will allow the development and adoption of good husbandry, as well as proper sanitary and biosecurity practices in order to prevent the transmission of Neospora caninum. To Cite This Article: García-Valle JL, Ruiz-Ramírez JA, Macedo-Barragán RJ, Lizama-Munguía T, Gutiérrez-Chávez AJ, García-Valle MG and García-Márquez LJ, 2024. Seroprevalence and risk factors associated with sheep neosporosis in colima, Mexico. Pak Vet J, 44(1): 195-199. http://dx.
... Since then, N. caninum has been described as a common cause of infections in a wide range of domestic and wild animals (Vitaliano et al., 2004;Kul et al., 2009;Martins et al., 2011;Mineo et al., 2011;Darwich et al., 2012;Moreno et al., 2012;Nasir et al., 2012). Although this parasite is widely distributed across all continents and found in most warm-blooded animal species, its sexual reproduction, which leads to environmental contamination by oocysts, occurs only in the gastrointestinal tracts of different canid species, such as dogs (McAllister et al., 1998), crab-eating foxes (Dubey, 2003), coyotes (Gondim et al., 2004), Australian dingoes (King et al., 2010) and gray wolves (Dubey and Schares, 2011). ...
Techniques for the measurement of parasite loads in different experimental models have evolved throughout the years. The quantification of stained slides using regular cytological stains is currently the most common technique. However, this modality of evaluation is labor-intensive, and the interpretation of the results is subjective because the successes of the assays mainly rely on the abilities of the professionals involved. Moreover, the novel genetic manipulation techniques that are commonly applied for closely related Toxoplasma gondii have not yet been developed for Neospora caninum. Thus, we aimed to develop a simple protocol for parasite quantification using pre-stained N. caninum tachyzoites and fluorescent probes based on ester compounds (i.e., CFSE and DDAO). For this purpose, we employed a quantification procedure based on flow cytometry analysis. Pre-stained parasites were also examined with a fluorescent microscope, which revealed that both dyes were detectable. Direct comparison of the numbers of CFSE+ and DDAO+ cells to the values obtained with classical cytology techniques yielded statistically comparable results that also accorded with genomic DNA amplification results. Although the fluorescence emitted by DDAO was more intense and provided better discrimination between the populations of parasitized cells, CFSE+ tachyzoites were detected for several days. In conclusion, this study describes a simple, fast, low-cost and reproducible protocol for N. caninum quantification that is based on parasite pre-staining with fluorescent ester-based probes.
... This coccidium affects domestic and wild animals, with special importance in dogs and cattle . The definitive hosts are dogs (McAllister et al., 1998) and some species of wild canids, such as coyotes (Gondim et al., 2004), dingoes (King et al., 2010) and gray wolves (Dubey et al., 2011). It is not considered to be a zoonotic agent, even though antibodies against N. caninum have already been found in humans (Lobato et al., 2006;Oshiro et al., 2015;Duarte et al., 2020) and DNA in blood samples from human umbilical cord (Duarte et al., 2020), however the parasite has not yet been detected in tissues. ...
Dogs can be infected by Toxoplasma gondii and Neospora caninum, for which they function, respectively, as intermediate, and definitive hosts. In the present study seroprevalence against T. gondii and N. caninum antibodies, were determined by indirect fluorescent antibody test (cut off of 16 and 50, respectively), in dogs that were treated at public veterinary hospitals in the metropolitan region of São Paulo and risk factors were identified. Out of the 1,194 samples 125 (10.5%; 95% CI: 8.8-12.3%) were positive for T. gondii and 9 (0.75%, 95% CI: 0.34-1.4%) for N. caninum. For T. gondii, statistical differences were observed between the proportions of positive dogs and different zones of the municipality (p = 0.025), and age (p = 0.02), higher among older dogs. The keepers were invited to answer an epidemiological questionnaire to analyze risk factors, and 471 (39.4%) agreed to be interviewed, and among their dogs 65 (13.8%) were T. gondii seropositive. Age group above 8 years (OR = 3.63; 95% CI: 1.08-12.23) was a risk factor and having a defined breed (OR = 0.49; 95% CI: 0.25-0.96) was a protective factor for T. gondii infection. Because of the low number of dogs positive for N. caninum, risk factors for this coccidium were not determined.
... This coccidium affects domestic and wild animals, with special importance in dogs and cattle . The definitive hosts are dogs (McAllister et al., 1998) and some species of wild canids, such as coyotes (Gondim et al., 2004), dingoes (King et al., 2010) and gray wolves (Dubey et al., 2011). It is not considered to be a zoonotic agent, even though antibodies against N. caninum have already been found in humans (Lobato et al., 2006;Oshiro et al., 2015;Duarte et al., 2020) and DNA in blood samples from human umbilical cord (Duarte et al., 2020), however the parasite has not yet been detected in tissues. ...
... Both parasites, T. gondii and N. caninum undergo sexual as well as asexual reproduction. Sexual reproduction occurs only in the definitive hosts, i.e., in felids for T. gondii [9] and in canids such as dog [10], coyote [11], dingo [12], and grey wolf [13] for N. caninum, respectively, and results in the shedding of oocysts. Asexual multiplication occurs in many tissues and organs of intermediate hosts, including Felidae and Canidae, and results in the formation of tissue cysts and potentially in clinical signs [14]. ...
Background:
Toxoplasma gondii and Neospora caninum are major protozoan parasites of worldwide distribution and significance in veterinary medicine and, for T. gondii, in public health. Cats and dogs, as final hosts for T. gondii and N. caninum, respectively, have a key function in environmental contamination with oocysts and, thus, in parasite transmission. Very little is known about the prevalence of T. gondii infections in dogs and cats in Egypt, and even less about the prevalence of N. caninum in the same hosts.
Methods:
In the current study, 223 serum samples of both dogs (n = 172) and cats (n = 51) were investigated for specific antibodies to T. gondii and N. caninum using commercially available ELISAs. A risk factor analysis was conducted to identify factors associated with seropositivity.
Results & discussion:
Exposure to T. gondii was reported in 23.3% of the dogs and in 9.8% of the cats, respectively. In addition, N. caninum-specific antibodies were recorded in 5.8% of dogs and in 3.4% of cats. A mixed infection was found in two dogs (1.2%) and in one cat (2%). Antibodies to T. gondii in dogs were significantly more frequent in dogs aged 3 years or more and in male German Shepherds. As this breed is often used as watchdogs and was the most sampled breed in Alexandria governorate, the purpose "watchdog" (compared to "stray" or "companion"), the male sex, and the governorate "Alexandria" also had a significantly higher seroprevalence for T. gondii. No factors associated with antibodies to N. caninum could be identified in dogs, and no significant factors were determined in cats for either T. gondii or N. caninum infection. Our study substantially adds to the knowledge of T. gondii infection in dogs and cats and presents data on N. caninum infection in cats for the first and in dogs in Egypt for the second time.
... Dogs are definitive hosts and responsible for oocyst shedding. Neospora caninum can be maintained also in the sylvatic cycle by wild canids: wolves (1), coyotes (2), and dingoes (3). Interestingly, red foxes are not competent definitive hosts (4). ...
Introduction
Neospora caninum is an important cause of abortion in cattle worldwide. Infection in cattle occurs horizontally by ingestion of oocysts shed by canids or vertically, from an infected dam to the fetus, and may result in abortion, stillbirth, or birth of seropositive offspring. The control of bovine neosporosis is difficult and costly. The objectives of this study were to estimate the current nationwide seroprevalence of N. caninum infections in Swiss cattle and to assess risk factors for infection with this parasite.
Methods
We conducted a cross-sectional study with cattle farms randomly selected and stratified according to population size, resulting in a sample of 780 female cattle. The cattle originated from 161 farms distributed over all Switzerland. The serum samples were tested for antibodies against N. caninum using a commercial ELISA and if inconclusive, retested using an in-house immunoblot technique. To collect farm parameters relevant to N. caninum transmission and prevention, farm owners were mailed a questionnaire which addressed topics putatively related to N. caninum infection such as husbandry, history of abortion, and presence of dogs on farm. Univariate analysis by generalized linear mixed model (with animal seropositivity as outcome variable) and logistic regression modeling (with farm seropositivity as outcome variable) was conducted on farm parameters investigated in the questionnaire.
Results
By ELISA and immunoblot, 4.2% (33/780) of cattle sera yielded positive results. At the farm level, 16.2% (26/161) of the sampled farms had at least one seropositive animal. The return rate of the valid questionnaires was 54.0%. At the animal level, odds for farm seropositivity were 3.8 times higher when rodents had been recorded by the farmer as a problem on the farm. At the farm-level, two protective factors were identified: rearing of replacement heifers and feeding of concentrated feed.
Conclusion
We recorded a low seroprevalence of N. caninum in a random sample of Swiss cattle representative for the years 2017–2018. Based on a questionnaire survey, we could identify risk and protective factors for infection with N. caninum, however their biological relevance needs to be confirmed in further studies.
... Dogs (13) and several other canids (14)(15)(16) are definitive hosts of N. caninum, shedding oocysts of the parasite in feces after consuming tissues of N. caninum-infected mice or cattle in experiments (17). Domestic dogs are the most widely distributed definitive host and are the major source of horizontal transmission to cattle worldwide. ...
Neospora caninum is a globally distributed abortifacient protozoan of cattle. Experimental infections with N. caninum in cattle have provided valuable information on host-parasite interaction and immunopathogenesis. Experimental infection of pregnant cows has been reported in about 20 articles, with most studies using cultured parasite tachyzoites as the inoculum. Only three experimental studies have been conducted in pregnant cows using the parasite's oocysts which are shed by dogs, in large part because transmission experiments using oocysts take more time and are more complex and expensive than experiments using tachyzoites. In this minireview, we discuss differences between N. caninum tachyzoites and oocysts as inocula for experimental infection of pregnant cows, as well as the route animals are inoculated.
... It is estimated that over US$1 billion are wasted annually in both dairy and beef cattle industries due to N. caninum infections [4]. The parasite circulates between wild/domestic canids, as definitive hosts, including dogs (Canis familiaris) [5], coyotes (Canis latrans) [6], dingoes (Canis dingo) [7], and gray wolves (Canis lupus) [8], and intermediate herbivorous hosts such as cattle and water buffalo (Bubalus bubalis) [9]. Based on a recent systematic review, the pooled prevalence of N. caninum infection among dogs was estimated to be 17.14% (95% confidence interval: 15.25% -1910%) worldwide [10]. ...
Neospora caninum is an economically significant parasite among livestock, particularly in dairy cattle herds, causing storm abortions. Vaccination seems necessary to limit the infection and its harsh consequences. This is the first steps towards developing a multi-epitope vaccine candidate against N. caninum using in silico approaches. High-ranked mouse MHC-binding and shared linear B-cell epitopes from six proteins (SRS2, MIC3, MIC6, GRA1, IMP-1 and Profilin) as well as IFN-γ inducing epitopes (from SAG1) were predicted, screened and connected together through appropriate linkers. Finally, RS-09 protein (TLR4 agonist) and histidine tag were added to N- and C-terminal of the vaccine sequence, yielding 486 residues in length. Physico-chemical properties showed a stable (instability index: 27.23), highly soluble, antigenic (VaxiJen score: 0.9554) and non-allergenic candidate. Secondary structure of the multi-epitope protein included 58.85% random coil, 20.99% extended strand and 20.16% alpha helix. Also, the tertiary structure was predicted, and further analyses validated a stable interaction between the vaccine model and mouse TLR4 (binding score: -1261.6). Virtual simulation of immune profile demonstrated potently stimulated humoral (IgG + IgM) and cell-mediated (IFN-γ) responses upon multi-epitope vaccine injection. Altogether, a potentially immunogenic vaccine candidate was developed using several N. caninum proteins, with the capability to elicit IFN-γ upsurge and other components of cellular immunity, and can be used in prophylactic purposes against neosporosis.
... Dogs and other related canids are the nal host of N. caninum, cattle, sheep while many mammals are intermediate hosts [5]. In the N. caninum life-cycle, canids are the only nal hosts that shed unsporulated oocysts through their feces into the environment, beside the intermediate host [6][7][8][9][10][11][12][13]. Dogs can be infected through three ways; ingestion of the infected tissues from the intermediate hosts, vertical transmission or consumption of the sporulated oocysts from the environment [14][15][16]. ...
Introduction: Neospora caninum is an important apicomplexan parasite causing neosporosis in cattle. The disease is recognized as one of the most important cause of reproductive problems and abortion in cattle worldwide. In this context, we developed an indirect ELISA with fusion protein rSRS2-SAG1-GRA7 for the diagnosis of neosporosis in aborted dairy cattle.
Results: The reaction conditions of the developed indirect ELISA were optimized. This indirect ELISA was compared to indirect immunoinfluscent assay (IFA), a total of 56 sera samples from cattle were used to evaluate the ELISA, the antibodies against N. caninum were tested by this ELISA to evaluate the prevalence of N. caninum in Ningxia. The sensitivity and specificity results of the rSRS2-SAG1-GRA7 indirect ELISA were 83.33% and 100%, the overall coincidence rate was 94.64%. N. caninum was prevalent in all the 4 cities investigated in Ningxia. The positive rate was from 16.67 to 100 %, and the mean rate was 41.64%.
Conclusions: This established rSRS2-SAG1-GRA7 indirect ELISA is capable of detecting serum antibodies against N. caninum, and due to its high sensitivity and specificity, it could be applied for serological evaluation and indirect diagnosis of N. caninum infection. And we assessed N. caninum seroprevalence in aborted dairy cattle from Ningxia province of China with this rSRS2-SAG1-GRA7 indirect ELISA.
... This protozoan also infects rodents, wild ungulates, birds, and marine mammals [4]. The parasite employs two hosts to complete its life cycle, so that dog (Canis familiaris) [5], dingo (Canis dingo) [6], coyote (Canis latrans) [7], and gray wolf (Canis lupus) [8] are definitive hosts, while cattle and buffalo are the most important intermediate hosts [9]. The parasite possesses three distinct infective stages, comprising tachyzoite (acute infection), bradyzoite (chronic infection), and sporozoite (environmental contamination) [10]. ...
Prevention of neosporosis is advantageous for cattle health and productivity. Previously, several vaccine candidates were nominated for vaccination against Neospora caninum. This study was premised on in silico evaluation of N. caninum IMP-1 in order to determine its physicochemical features and immunogenic epitopes. We employed a wide array of network-based tools for the prediction of antigenicity, allergenicity, solubility, posttranslational modification (PTM) sites, physicochemical properties, transmembrane domains and signal peptide, secondary and tertiary structures, and intrinsically disordered regions. Also, prediction and screening of potential continuous B cell peptides and those epitopes having stringent affinity to couple with mouse major histocompatibility complex (MHC) and cytotoxic T lymphocyte (CTL) receptors were accomplished. The protein had 393 residues with a molecular weight of 42.71 kDa, representing aliphatic index of 85.83 (thermotolerant) and GRAVY score of -0.447 (hydrophilic). There were 47 PTM sites without a signal peptide in the sequence. Secondary structure comprised mostly of extended strand and helices, followed by coils. The Ramachandran plot of the refined model showed 90.1%, 9.9%, 0.0%, and 0.0% residues in the favored, additional allowed, generously allowed, and disallowed regions, correspondingly. Additionally, various potential B cell (linear and conformational), CTL, and MHC binding epitopes were predicted for N. caninum IMP-1. The findings of the present study could be further directed for next-generation vaccine design against neosporosis.
... Neospora caninum is a parasitic protozoan parasite of Apicomplexa and it is known to cause reproductive disorders of pregnant animals (including miscarriage, stillbirth, and weak births) and neurological dysfunction of newborns ((Marsh et al., 1998;Dubey, 2003). Dogs (including Australian dingoes), coyote, and gray wolf are definitive hosts, and the range of intermediate hosts is notably wide and includes almost all warm-blooded animals (Dubey, 2003;Dubey et al., 2007;King et al., 2010). Neospora-infection in dairy cattle has emerged as a major cause of abortion throughout the world and causes more than $1.298 billion in annual losses globally (Reichel et al., 2013). ...
Neospora caninum, an intracellular protozoan, has attracted much attention because of the etiology of reproductive disorders in cattle. Although numerous relevant studies have been published, the overall prevalence of Neospora caninum infection among cattle in mainland China is still unknown, and associated risk factors need to be evaluated to establish preventive measures. We systematically searched four databases for epidemiologic studies that investigated the prevalence and associated risk factors of this parasite among cattle in mainland China. A total of 33,945 cattle from 51 studies were tested. The pooled prevalence of N.caninum among cattle in mainland China was 13.69% (95% CI: 10.86%-17.12%) through the random-effects model, which showed high heterogeneity, I² = 98%. The analysis showed that Neospora infection-positive cows were 2.42 times more likely to abort than infection-negative cows (OR 2.42; 95% CI: 2.07-2.84). Our analysis indicated that Neospora-infection is widely distributed among cattle in China, which reinforces the importance of adequate prevention and control strategies to reduce economic losses for the cattle industry.
... The life cycle of N. caninum is facultative heteroxenous with definitive hosts (DH) from the genus Canis, including domestic and wild dogs (Canis lupus familiaris), Coyotes (Canis latrans), Gray wolves (Canis lupus lupus), and Dingoes (Canis lupus dingo) [7][8][9][10][11]. The main intermediate host (IH) is cattle, however, many warm-blooded vertebrates' species could be infected, some with the potential to serve as intermediate hosts in domestic and sylvatic transmission cycles [12]. ...
The Pampas fox (Lycalopex gymnocercus) is the most abundant wild canid from South America. This wild canid inhabits grasslands, open woodlands, and areas highly modified by extensive ranching and agricultural activities. We aimed to evaluate Neospora caninum infection in tissues from the Pampas fox from Argentina. A total of 41 free-living Pampas foxes were sampled in rural areas located in the Humid Pampas region, Argentina. Brain tissue and different muscles were assessed by histologic and molecular methods. No N. caninum cysts were observed in brain and muscle tissue samples analyzed by histology and immunohistochemistry. Molecular N. caninum identification from brain tissue was based on amplification by PCR of Nc-5 gene and ITS1 rRNA fragments and subsequent sequencing. The presence of N. caninum DNA was 74% (23/31) for the Nc-5 gene and was confirmed by a second ITS1 PCR in 55% (17/31) of the brain tested. Thirteen ITS1 consensus sequences were obtained, and all have a 99.58–100% similarity with N. caninum reference sequences. Only 4% (1/23) of muscles samples analyzed were positive for the Nc-5 gene of N. caninum. This study demonstrated a high prevalence of N. caninum DNA in brain from free-ranging Pampas fox of the Pampa Argentine, thus confirming that this wild canid is a wide distributed intermediate host.
... Canids, such as the domestic dog, Australian dingo, coyote, and gray wolf, are definitive hosts of this parasite Gondim et al., 2004;King et al., 2010;McAllister et al., 1998); however, the infection has also been described in several other species, including birds, buffaloes, horses, and goats (de Barros et al., 2020(de Barros et al., , 2018Dubey and Schares, 2011). DNA from the parasite was detected in human umbilical cord blood, indicating a potential zoonotic parasite; however, further studies are needed to clarify this (Duarte et al., 2020). ...
Neosporosis, an infectious disease caused by the protozoan Neospora caninum, has been associated with economic losses in cattle rearing worldwide. However, previous studies have not presented any evidence regarding the association between serological status of neosporosis and alteration of the reproductive parameters. Thus, this study aimed to determine whether N. caninum is associated with reproductive disorders and to evaluate the possible risk factors of the infection. Blood samples from 202 dairy cows, 51 with a history of reproductive disorders (case group) and 151 without (control group), were collected from different farms in Brazil. Epidemiological questionnaires were conducted with all the farmers. Serum samples were subjected to an indirect fluorescent antibody
test to detect antibodies against the parasite. In total, 28.22% (57/202) of the cows were seropositive: 47.06% (24/51) from the case group and 21.85% (33/151) from the control group. By logistic regression, cows aged ≥48 months and cows with history of abortion were 4.8 (95% confidence interval [CI] = 1.91–12.05; p = 0.001) and 2.3 (95% CI = 1.06–5.1; p = 0.034) times more likely to be seropositive, respectively. Furthermore, our results show an association between N. caninum seropositivity and abortion in dairy cows from Brazil with poor management conditions and N. caninum seropositivity risk factors for reproductive disorders.
... The main transmission route of N. caninum is vertical in cattle, and probably also in European bison [52]; however, other transmission routes may also exist. Dogs (Canis lupus familiaris), coyotes (Canis latrans), dingoes (Canis lupus dingo) and gray wolves (Canis lupus) have been confirmed as definitive hosts [53][54][55]. In our studies, N. caninum infection was clearly more prevalent in European bison from the Bieszczady Mountains than in other subpopulations; this may be a result of the high density of the grey wolf population in this location: 9.2 individuals per 100 m 2 , compared to the mean value of 2.69 individuals per 100 m 2 for Poland as a whole (http:// www. ...
Background
The European bison is an endangered species, and as such it is extremely important to monitor herds for pathogens which can lead to reproductive failure. The aim of the present study was to determine the current prevalence of antibodies to pathogens known to potentially influence reproduction in European bison. Serum samples from 183 bison, originating from different parts of Poland, were tested using commercial ELISA tests for antibodies to Chlamydia spp., Coxiella burnetti, Leptospira interrogans, Neospora caninum and Toxoplasma gondii ; the findings were compared between captive and main free-ranging herds, and with regard to the influence of demographic factors such as age and sex. The prevalence of seropositivity was also checked with regard to location and the animal species sharing it.
Results
Chlamydia spp. antibodies were present in 48 out of 130 (36.9%) tested samples. Coxiella burnetii was found in one sample out of 178 (0.58%). N. caninum in 36 out of 172 (20.9%) and T. gondii in 23 out of 172 (13.4%). No sample was positive for leptospirosis. Neither sex nor age appeared to have a significant effect on the occurrence of antibodies to the identified species. The prevalence of Chlamydia spp. in the samples varied significantly according to location; however, similar frequency ranges were observed between free ranging and captive herds. In contrast, antibodies to N. caninum were more common in free-ranging herds than captive herds, with the highest frequency observed in the Bieszczady Mountains.
Conclusions
Chlamydia spp., N. caninum and T. gondii might have a similar impact on the reproductive potential of European bison as they have on cattle. The high occurrence of antibodies to N. caninum in bison from the Bieszczady Mountains may be associated with the relatively high density of the wolf population in the area.
... El ciclo de vida de N. caninum es heteroxeno, siendo el perro doméstico (Canis lupus familiaris), coyote (Canis latrans), dingo (Canis familiaris dingo) y lobo gris (Canis lupus) los HD, quienes descargan los ooquistes no esporulados al medio ambiente con la materia fecal (Basso et al., 2001;Dubey et al., 2011Dubey et al., , 2014Gondim et al., 2004;King et al., 2010;McAllister et al., 1998). Posteriormente los ooquistes esporulan bajo determinadas condiciones de temperatura y humedad, siendo infectivos para los hospedadores intermediarios (HI) cuando son ingeridos con el alimento y/o agua contaminada. ...
La neosporosis es una enfermedad de gran impacto en el ganado vacuno debido a que causa abortos en el segundo y último trimestre de la gestación. En esta revisión se resume y discute la información sobre la misma, recopilada de dos décadas y media de estudios en bovinos de Argentina. Se aportan datos sobre el diagnóstico, la prevalencia y los avances en el estudio de la enfermedad. Está dirigida a los médicos veterinarios dedicados al diagnóstico y a la investigación de la neosporosis y/o a la producción bovina.
... Neospora caninum is a protozoan parasite belonging to Phylum Apicomplexa that has an indirect biological cycle (Dubey et al. 2017), in which the dog, coyote, dingo and grey wolf are recognized as definitive hosts (McAllister et al. 1998;Gondim et al. 2004;King et al. 2010;Dubey et al. 2011), while a wide range of domestic wild animals can act as intermediary hosts (Dubey et al. 2017); the cattle are the most susceptible domestic species to infection, in which abortion and reproductive disorders occur with significant economic effects (Reichel et al. 2013). The domestic chicken (Gallus gallus domesticus) can also act as an intermediary host of N. caninum; it has been considered that the chicken raised in free-range conditions are exposed due to their management and herding habits to ingesting the parasites' oocysts that are present on the ground; therefore, these animals can be a good indicator of the environmental pollution with oocysts excreted by the canids (Costa et al. 2008;Dubey et al. 2017). ...
The objective of the present study was to investigate the epidemiology of natural infection by N. caninum in free-range chickens from Aguascalientes, Mexico, through identifying the presence of antibodies, its association with certain risk factors, and estimate the frequency of parasite DNA detection in the brain. The study included 150 clinically healthy chickens from 81 small family farms distributed throughout the state, from which blood and brain samples were taken. Serum samples were processed by indirect immunofluorescence considering a dilution of 1:50 as a positive reaction, while the DNA detection was done by PCR; the association between the presence of antibodies and the potential risk factors was estimated through logistic regression. The general anti-N. caninum presence of antibodies in the studied population was 46% (69/150, CI 95% 38–54), with titers of 1:50 in 38, 1:100 in 24, and 1:200 in 7, finding positive cases in 49% of the farms and in 91% of the municipalities that integrate the state. The presence of antibodies found in the municipalities was estimated in a range of 20 to 75%. The frequency of DNA detection was 6% (9/150, CI 95% 2–11). The grain supplementation was identified as the unique risk factor for infection (OR = 2.82; 95% CI, 1.18–6.73, p < 0.019).
... Neospora caninum is an obligatory intracellular coccidian parasite, closely related to Toxoplasma gondii (Dubey et al., 2017), and was first described in 1988 by Dubey et al. (1988). There are three infective stages which comprise an elaborate life cycle: (i) the sporozoites encapsulated in oocysts, which are formed in the intestine of the definitive hosts (Dubey et al., 2017) (dogs (McAllister et al., 1998, grey wolves (Dubey et al., 2011), dingoes (King et al., 2010) and coyotes (Gondim et al., 2004)), and are shed through faeces in the environment; (ii) the tachyzoites, which represent the proliferative and disease-causing stage; and (iii) the bradyzoites, which proliferate slowly and form intracellular tissue cysts that can persist for extended periods of time without causing inflammatory reactions. Infection can take place orally, through ingestion of bradyzoite-infected tissue cysts or accidently by uptake of oocysts. ...
The apicomplexan parasite Neospora caninum is an important causative agent of congenital neosporosis, resulting in abortion, birth of weak offspring and neuromuscular disorders in cattle, sheep, and many other species. Among several compound classes that are currently being developed, two have been reported to limit the effects of congenital neosporosis: (i) bumped kinase inhibitors (BKIs) target calcium dependent protein kinase 1 (CDPK1), an enzyme that is encoded by an apicoplast-derived gene and found only in apicomplexans and plants. CDPK1 is essential for host cell invasion and egress; (ii) endochin-like quinolones (ELQs) are inhibitors of the cytochrome bc1 complex of the mitochondrial electron transport chain and thus inhibit oxidative phosphorylation. We here report on the in vitro and in vivo activities of BKI-1748, and of ELQ-316 and its respective prodrugs ELQ-334 and ELQ-422, applied either as single-compounds or ELQ-BKI-combinations. In vitro, BKI-1748 and ELQ-316, as well as BKI-1748 and ELQ-334, acted synergistically, while this was not observed for the BKI-1748/ELQ-422 combination treatment. In a N. caninum-infected pregnant BALB/c mouse model, the synergistic effects observed in vitro were not entirely reproduced, but 100% postnatal survival and 100% inhibition of vertical transmission was noted in the group treated with the BKI-1748/ELQ-334 combination. In addition, the combined drug applications resulted in lower neonatal mortality compared to treatments with single drugs.
... La N. caninum en caballos ha sido asociada a abortos y problemas reproductivos (5)(6)(7)(8) , mientras que N. hughesi está relacionada con enfermedades neurológicas (9)(10)(11) , también, asociada con Sarcosystis neuronae, causante de mieloencefalitis protozoaria equina (MPE), identificada como una enfermedad neurológica grave de los caballos, que produce pérdidas significativas en la producción equina, principalmente reportado en Estados Unidos (12) . Los hospederos definitivos de N. caninum identificados son el perro doméstico (13) , coyote (14) , dingo australiano (15) y lobo gris (16) , y como hospederos intermediarios varias especies silvestres y domésticas (17) , sin embargo, los hospederos definitivos de N. hughesi, no se han identificado y el caballo es considerado como único hospedero intermediario potencial (18) . La infección puede ocurrir debido a la ingestión de ooquistes esporulados en alimento o agua contaminados; con respecto a la transmisión vertical actualmente es considerada solo como ruta alternativa (19,20) . ...
Neospora spp. es un parásito protozoario causante de abortos y enfermedad del Sistema Nervioso Central (SNC) en diversas especies domésticas y silvestres. En equinos, se le ha involucrado como causa de aborto, mortalidad neonatal y enfermedades del SNC. La especie identificada en equinos es distinta a Neospora caninum y se denomina Neospora hughesi. El objetivo del presente, fue detectar la presencia de anticuerpos anti-Neospora spp., asociados a factores de riesgo en caballos de México. Se realizó una encuesta de cada cuadra y animales individuales de cuatro regiones del país (Centro, Norte, Occidente y Sur) para identificación de los factores de riesgo. Se obtuvo un total de 684 muestras de sueros de caballos de las diferentes regiones, 52.3 % (358) machos y 47.7 % (326) hembras. Los sueros fueron conservados a -20 °C. El diagnóstico se realizó mediante la técnica de inmunofluorescencia indirecta (IFI), los resultados de este fueron analizados para estimar la asociación entre la seropositividad y los factores de riesgo. La seroprevalencia a Neospora spp. fue de 2.34 % en la población estudiada; los casos positivos se encontraron principalmente en tres de las cuatro regiones incluidas, que presentaron una relación significativa a la presencia de anticuerpos anti-Neospora spp.; la convivencia de los caballos con otros animales obtuvo un valor de OR de 2.34 (IC 95%: 0.28 - 19.0; P<0.04). Se concluye que, Neospora spp., está presente en los caballos de México.
... In contrast, N. caninum infects primarily cattle, causing abortions with an estimated impact of a billion dollars on the worldwide economy annually (Reichel et al. 2013). Feline species act as definitive hosts of T. gondii, whereas sexual replication of N. caninum occurs only in canids (McAllister et al. 1998;Gondim et al. 2004;King et al. 2010). These biological differences have been largely ascribed to absence, point mutations, and pseudogenization of T. gondii virulence factors in N. caninum and the comparative amplification of surface protein-coding gene families in N. caninum (Khan et al. 2009;Reid et al. 2012). ...
Neospora caninum primarily infects cattle, causing abortions, with an estimated impact of a billion dollars on the worldwide economy annually. However, the study of its biology has been unheeded by the established paradigm that it is virtually identical to its close relative, the widely studied human pathogen Toxoplasma gondii By revisiting the genome sequence, assembly, and annotation using third-generation sequencing technologies, here we show that the N. caninum genome was originally incorrectly assembled under the presumption of synteny with T. gondii We show that major chromosomal rearrangements have occurred between these species. Importantly, we show that chromosomes originally named Chr VIIb and VIII are indeed fused, reducing the karyotype of both N. caninum and T. gondii to 13 chromosomes. We reannotate the N. caninum genome, revealing more than 500 new genes. We sequence and annotate the nonphotosynthetic plastid and mitochondrial genomes and show that although apicoplast genomes are virtually identical, high levels of gene fragmentation and reshuffling exist between species and strains. Our results correct assembly artifacts that are currently widely distributed in the genome database of N. caninum and T. gondii and, more importantly, highlight the mitochondria as a previously oversighted source of variability and pave the way for a change in the paradigm of synteny, encouraging rethinking the genome as basis of the comparative unique biology of these pathogens.
... It has a worldwide distribution and causes foetal losses or stillbirth in livestock, especially cattle [1,2]. Domestic dogs and other phylogenetically closely related wild carnivores like coyotes, wolves, or dingoes are the only known definitive hosts of N. caninum [1,[3][4][5], i.e. hosts, in which sexual recombination can take place. The main mode of transmission in cattle, which are important intermediate hosts of the parasite, seems to be endogenous vertical transmission [1,2], i.e. transmission from a persistently or chronically infected dam to her offspring [6]. ...
Background
Neospora caninum , a coccidian protozoan, represents an important cause of bovine abortion. Available N. caninum strains show considerable variation in vitro and in vivo , including different virulence in cattle. To which extent sexual recombination, which is possible in the intestines of domestic dogs and closely related carnivores as definitive hosts, contributes to this variation is not clear yet.
Methods
Aborted bovine foetuses were collected between 2015 and early 2019 from Italian Holstein Friesian dairy herds suffering from reproductive problems. A total of 198 samples were collected from 165 intensive farms located in Lombardy, northern Italy. N. caninum samples were subjected to multilocus-microsatellite genotyping using ten previously established microsatellite markers. In addition to our own data, those from a recent study providing data on five markers from other northern Italian regions were included and analysed.
Results
Of the 55 samples finally subjected to genotyping, 35 were typed at all or 9 out of 10 loci and their individual multilocus-microsatellite genotype (MLMG) determined. Linear regression revealed a statistically significant association between the spatial distance of the sampling sites with the genetic distance of N. caninum MLMGs ( P < 0.001). Including data from this and a previous North Italian study into eBURST analysis revealed that several of N. caninum MLMGs from northern Italy separate into four groups; most of the samples from Lombardy clustered in one of these groups. Principle component analysis revealed similar clusters and confirmed MLMG groups identified by eBURST. Variations observed between MLMGs were not equally distributed over all loci, but predominantly observed in MS7, MS6A, or MS10.
Conclusions
Our findings confirm the concept of local N. caninum subpopulations. The geographic distance of sampling was associated with the genetic distance as determined by microsatellite typing. Results suggest that multi-parental recombination in N. caninum is a rare event, but does not exclude uniparental mating. More comprehensive studies on microsatellites in N. caninum and related species like Toxoplasma gondii should be undertaken, not only to improve genotyping capabilities, but also to understand possible functions of these regions in the genomes of these parasites.
Graphical Abstract
... Neospora caninum is an obligate intracellular protozoan that belongs to the phylum Apicomplexa (Dubey et al., 1988). It emerged as a serious disease in cattle and dogs (Dubey, 2003), with canids (Canis domesticus, Canis lupus dingo, Canis latrans, Canis lupus) as definitive hosts (McAllister et al., 1998;King et al., 2010;Gondim et al., 2004;Dubey et al., 2011). The forms of transmission are similar to toxoplasmosis and can be horizontal or vertical. ...
Neospora caninum is an obligate intracellular protozoan with canids (Canis domesticus, Canis lupus dingo, Canis latrans, Canis lupus) as its definitive hosts. The objective of this study was to detect anti-N. caninum antibodies in pregnant women seen at referral center for prenatal screening in the state of state Mato Grosso do Sul, Brazil. A total of 188 serum samples from pregnant women provided by the Instituto de Pesquisa, Ensino e Diagnósticos da APAE de Campo Grande (IPED/ APAE) were subjected to IFA test and western blot analysis. The samples were divided into three groups: 23/99 samples from the seropositive group for toxoplasmosis were positive for anti-N. caninum IgG antibodies, and 9/99 positive for IgM; in the HIV group, 7/33 were positive for IgG; and in the HIV+toxoplasmosis group, 13/56 were positive for IgG and two positive for IgM. The seropositivity for IgG was assessed by western blot by testing 43 IFA test positive samples using rNcSRS2 (Nc-p43) as antigen. The serological results of the present study suggest that exposure of these pregnant women to the parasite N. caninum and presence of IgM antibodies are indicative of recent infection. Further studies are needed to establish the possibility of active infection.
... It has a worldwide distribution and causes foetal losses or stillbirth in livestock, especially cattle [1,2]. Domestic dogs and other phylogenetically closely related wild carnivores like coyotes, wolves, or dingoes are the only known de nitive host of N. caninum [1,3,4,5], i.e. hosts in which sexual recombination can take place. The main mode of transmission in cattle, the main intermediate host of the parasite, seems to be endogenous vertical transmission [1,2], i.e. transmission from a persistently or chronically infected dam to her offspring [6]. ...
Background: Neospora caninum, a coccidian protozoan, represents an important cause of bovine abortion. While only a single genotype of N. caninum exists word-wide, available N. caninum strains show considerable variation in vitro and in vivo, including different virulence in cattle. To which extent sexual recombination, possible in the intestines of domestic dogs and closely related carnivores as definitive hosts, contribute to this variation is not clear, yet.
Methods: Aborted bovine foetuses were collected between 2015 and early 2019 from Italian Holstein Friesian dairy herds suffering from reproductive problems. A total of 198 samples were collected from 165 intensive farms located in Lombardy, northern Italy. N. caninum samples were subjected to multilocus-microsatellite genotyping (MLMG) using ten previously established microsatellite markers. In addition to own data, those from a recent study providing data on five markers from other northern Italian regions were included and analyzed.
Results: Of the 55 samples finally subjected to MLMG, 35 were typed at all or 9 out of 10 loci. Linear regression revealed a statistically significant association between the spatial distance of the sampling sites with the genetic distance of N. caninum MLMGs (P< 0.001). Including data from a previous North Italian study (eBURST analysis) revealed that part of N. caninum MLMGs from northern Italy separate into four groups; most of the samples from Lombardy clustered in one of these groups. Principle component analysis revealed similar clusters and confirmed MLMG groups identified by eBURST. Variations observed between MLMGs were not equally distributed over all loci, but predominantly observed in MS7, MS6A, or MS10.
Conclusions: Our findings confirm the concept of local N. caninum subpopulations. The geographic distance of sampling was associated with the genetic distance as determined by MLMGs. Results suggest that multi-parental recombination in N. caninum is a rare event, but does not exclude uniparental mating. More comprehensive studies on microsatellites in N. caninum and related species like Toxoplasma gondii should be undertaken, not only to improve genotyping capabilities, but also to understand possible functions of these regions in the genomes of these parasites.
... Dogs and related canids (coyotes, wolves) are definitive hosts of N. caninum (Klein, Barua, Liccioli, & Massolo, 2019). In addition, Australian dingoes or wild dogs (Canis lupus dingo) have been also identified as definitive host of N. caninum (King et al., 2010). The life cycle consists of three known infectious stages: tachyzoites, tissue cysts and oocysts. ...
An outbreak of 92 abortions out of 1,700 pregnant cows (5.41%) in a period of 3 weeks (19 May to 05 June 2019) occurred in a Georgia Dairy, USA, in cattle that were between 3 and 7 months of gestation. Two sets of samples (aborted fetuses’ organs, placental tissues, aborted cows blood) were submitted for laboratory investigations at the Tifton Veterinary Diagnostic and Investigational Laboratory, College of Veterinary Medicine, University of Georgia (TVDIL, Tifton, GA, USA). An abortion panel testing for the major abortion‐causing agents [e.g. Bovine Viral Diarrhoea Virus (BVDV), Infectious Bovine Rhinotracheitis Virus/ Bovine Herpes Virus‐I (IBR/ BHV‐I), Brucella spp., Leptospira spp.] was conducted on several of the samples. On the first set of samples, microbial cultures, serology and PCR tests for the common abortifacient agents revealed the presence of Neospora caninum (N. caninum) DNA, which was positive by PCR on the placenta and fetal tissues. The second set of diagnostic investigations also identified two out of three submitted freshly aborted fetuses to be positive for N. caninum by PCR and immunohistochemistry. Moreover, all three dams were also sero‐positive for N. caninum. The entire herd was being fed on grass silage harvested from a pasture where feral pigs were hunted previously and carcasses were left behind. As a consequence of this action a large population of wild coyotes were attracted to these carcasses, and likely contaminated the pasture with potential N. caninum‐infected feces. After the abortion outbreak was resolved, it was recommended that the farmers should avoid disposal of cadavers of hunted animals in the wild, as it could attract carnivorous and omnivorous animals that may potentially spread the disease to the cattle and other wildlife.
... In cattle, N. caninum is considered one of the major causes of abortion and responsible for severe economic losses (6). To date, only domestic dogs (Canis familiaris), Australian dingoes (Canis lupus dingo), coyotes (Canis latrans), and gray wolves (Canis lupus) are considered definitive hosts of the parasite (59)(60)(61)(62). Although serological positivity against N. caninum was reported in several animal species, only a few are considered intermediate hosts, including some mammalian and bird species (58,63). ...
Toxoplasmosis and neosporosis are diseases with worldwide distribution that are associated with reproductive problems in livestock and responsible for economic losses. This review presents an overview of the current knowledge relative to these diseases in water buffalo (Bubalus bubalis). In general, buffalo are considered resistant to clinical toxoplasmosis because there are studies only reporting serological evidence of natural infection in these animals. Studies have described age, poor hygienic status of the farm, and presence of cats as risk factors for the development of Toxoplasma gondii infection in buffalo. It must be highlighted that buffalo meat, which does not receive adequate freezing treatment, could be a potential source for toxoplasmic human infection as well as the importance of raw buffalo milk in the transmission of toxoplasmosis to human beings. Neospora caninum is considered one of the major causes of abortion and responsible for huge economic losses in cattle. Vertical transmission is the main route to infect calves, and is responsible for maintaining the parasite within a herd. In buffalo, vertical transmission is also described; moreover, although there are indications that N. caninum may be associated with abortion in dairy buffalo, the reproductive importance of neosporosis is apparently lower in buffalo relative to cattle. Most studies have identified a higher time of exposition to N. caninum oocysts relative to age. The household system was also described as a risk factor for infection, possibly due to persistent contact between the home-raised buffalo and canids. The fetal immune competence of buffalo is similar to bovine, and buffalo fetus are highly susceptible to infection during the first trimester of pregnancy, indicating that N. caninum may be an abortigenic agent in buffaloes. Alternatively, it is interesting to note there is evidence that the inflammatory response in pregnant buffalo infected with N. caninum is mild enough to avoid abortion in most cases. It is proposed that the possible transmission of toxoplasmosis through unprocessed milk and buffalo meat may occur, which is important in terms of public health. Additionally, there is strong evidence to suggest that N. caninum may be associated with abortion in buffalo.
Sarcocystis spp. son parásitos intracelulares del phylum o tipo Apicomplexa, pertenecientes a la familia Sarcocystidae, conocidos vulgarmente como “coccidios formadores de quistes”, particularidad que explica el nombre del género (del griego sarkos= músculo y kystis= vesícula o quiste), y refuerza la relación filogenética con otros protozoos de la familia como Neospora caninum y Toxoplasma gondii.
En 1843, el investigador suizo Friedrich Miescher, fue quien por primera vez encontró quistes en músculo estriado de ratón (Mus musculus) y los informó como "fibrillas blanquecinas", y durante los siguientes 20 años fueron identificados como túbulos de Miescher (Levine, 1986). Sin embargo, recién en 1972 fue descripto e identificado el ciclo biológico como indirecto obligado para las distintas especies que integran este género (Heydorn & Rommel, 1972). Se sabe que estos protozoos producen, por multiplicación asexual, quistes en los músculos de sus hospedadores intermediarios (HI) como los herbívoros, y ooquistes con esporocistos por reproducción sexual y esporulación, en el intestino de sus hospedadores definitivos (HD), como carnívoros, omnívoros, carroñeros o caníbales.
Actualmente, se conocen cerca de 250 especies de Sarcocystis, las cuales infectan mamíferos, aves y reptiles de todo el mundo. La sarcocystosis es principalmente una infección de y entre animales. Sin embargo, algunas especies como S. hominis, S. suihominis tienen homínidos como HD, que se infectan tras la ingesta de carne cruda y/o poco cocida de bovinos o porcinos, respectivamente, pudiendo producir una sintomatología digestiva leve y autolimitante. A su vez, el hombre también puede actuar como hospedador accidental (también conocido como hospedador aberrante) para varias especies de Sarcocystis, mediante la ingestión de ooquistes o esporocistos, con manifestaciones musculares por multiplicación asexual de los protozoos (Fayer, 2004).
Neospora caninum (N. caninum) is one of the causative agents that causing cattle abortion, and severe economic losses. Due to the scarcity of data on N. caninum infection in Egyptian cattle, the purpose of this study was to estimate the seroprevalence and determine the risk factors for parasite infection. In four governorates in northern Egypt, 540 blood samples from cattle were taken, and tested using a commercial ELISA kit. The overall seroprevalence of N. caninum in examined cattle was 28.89%. A multivariate logistic regression model determined that age (OR = 2.63, P < 0.001), manual milking (OR = 1.39, P = 0.14), abortion history (OR = 2.78, P < 0.0001), repetition of estrus (OR = 2.31, P < 0.0001), and contact with dogs (OR = 2.57, P < 0.0001) were significant risk factors. The findings proved that N. caninum infection was one of the factors contributing to abortion and financial losses in dairy cattle in Egypt. Therefore, the application of sanitary security and control programs is very important in dairy farms.
Bovine neosporosis is a globally important disease, causing abortions and significant economic losses. In Brazil, studies on neosporosis in cattle are few and based on limited samples and/or from limited areas. We aimed to determine the herd and animal levels seroprevalence and associated factors for Neospora caninum infections in cattle from the state of Paraíba, Northeastern Brazil, using a planned sampling. Herds (n = 434) and cows aged ≥24 months (n = 1891) were randomly selected, and serum samples were tested with the immunofluorescence antibody test (IFAT) using as cut-off point the antibody titer 200. Herd-level and animal-level seroprevalences were 17.8% (95% CI = 14.3%-21.8%) and 18.1% (95% CI = 14.7%-22.1%), respectively. The factors associated with N. caninum infection were farm located in the Sertão mesoregion (Prevalence ratio [PR] = 2.37), mixed production (PR = 1.64), herd size of 34-111 animals (PR = 3.50) and herd size >111 animals (PR = 6.14). The results indicate high N. caninum circulation in the bovine population of the state of Paraíba, semiarid of Brazil, mainly in the Sertão mesoregion, where the highest apparent herd and animal-level prevalences of positive herds were identified. Control strategies should be adopted to mitigate the impact of disease on cattle production, as well as it's suggested the encouragement of conducting surveys in wildlife from Caatinga biome, mainly canids, to provide information on the importance of these animals on the epidemiology of bovine neosporosis.
Introduction
Neospora caninum is one of the main causes of abortion in cattle. In wildlife, the occurrence and relevance of vertical infection have not been yet clearly evaluated. The aim of this study was to verify the possibility of vertical transmission of N. caninum in three wild species extensively distributed in Europe, namely roe deer Capreolus capreolus, wild boar Sus scrofa and red fox Vulpes vulpes.
Methods
A total of 190 fetuses (72 wild boars, 67 foxes and 51 roe deer) from 61 females were included in the study. All animals, which were either found dead or culled within selective control plans in North-western Italy, were tested, in parallel by PCR on central nervous system, skeletal muscle and kidney.
Results and discussion
The efficiency of vertical transmission in the three target species was of 87.5% (95% CI 69.00–95.66).
Invasive organisms are key drivers of environmental change globally. Both native and non-native species can become pests that require management or control. Vertebrate pest animals may cause a range of economic, environmental and social impacts for which various plans are developed at a local, state and national scale to aid their management. There are multiple vertebrate pest species in Australia which vary in the type and severity of their negative effects. Prioritisation of these pests and their impacts is critical for management to be cost-effective. We accessed
pest management plans (PMPs) from 66 (of 71) local government areas (LGAs) across the state of Queensland to collate a list of vertebrate pest species present in each LGA. Local government areas were then grouped into easily identifiable regions (Regional Organisation of Councils, ‘ROC’ regions, 10 in all) and vertebrate pest species lists were collated for each region. At regional workshops, each pest
species was ranked as no, low, medium or high priority by stakeholders. Rankings were used to develop impact scores resulting in a priority list of vertebrate pest animal species at the state level. Fifty-three species were identified in individual LGA PMPs of which 25 were considered priorities at the regional level. Most
species prioritised at the state level were mammals, with Wild Dogs (including Dingoes; Canis familiaris), Feral Pigs (Sus scrofa) and Feral Cats (Felis catus) being the three highest ranked. Similarities in priority species were evident across ROC regions, however, several regions prioritised pests specific to their location. The data supported a further amalgamation of the 10 ROC regions into five main groups based on the set of vertebrate pest species that were present. Prioritisation lists
should be regularly updated as technologies develop, established pest animal impacts change and new species incursions occur.
Background
Infections with the coccidian parasite Neospora caninum affect domestic and wild animals worldwide. In Australia, N. caninum infections cause considerable losses to the cattle industry, but livestock infection source is contentious. Similarly, the role of wild animals, such as wild deer and kangaroos, in maintaining the parasite cycle is also unclear. It is possible that native or introduced herbivorous species could be reservoir hosts of N. caninum in Australia, but to date, this has not been investigated.
Results
We report here the first large-scale screening of the immune status of wild deer in Australia, spanning three species. In so doing, we also assessed two commercial cELISA tests validated for detecting N. caninum in cattle for their ability to detect N. caninum antibodies in serum samples of wild deer. N. caninum antibodies were detected in 3.7% of the wild deer serum samples collected in south-eastern Australia (n = 189), including 97 fallow deer, 14 red deer, and 78 sambar deer.
Conclusions
Overall, our study provides the first evidence of N. caninum antibody profiles in wild deer, quantifying deer's potential role in the sylvatic cycle of N. caninum, and epidemiological baseline information relevant for managing N. caninum infections in Australia.
p>La neosporosis es una enfermedad que puede afectar a una amplia gama de huéspedes entre ellos caninos, bovinos, ovinos, caprinos, búfalos, ciervos, equinos y especies carnívoras, incluidos géneros silvestres. Dicha enfermedad es causada por Neospora caninum, parásito protozoario (coccidio) que genera un quiste de tejido intracelular perteneciente a la familia Sarcocystidae. Los caninos son los huéspedes definitivos y los hospedadores intermedios más comunes son los bovinos. El ciclo de vida de N. caninum se caracteriza por ser hete- roxeno facultativo complejo, que involucra un hospedador cánido definitivo, donde ocurre la replicación sexual y una gama de hospedadores intermediarios donde tiene lugar la replica- ción asexual. Después de pasar estas fases el canino elimina ooquistes a través de las heces contaminando así el alimento del ganado y por ende infectando al mismo. La transmisión vertical es la principal vía de contagio de los bóvidos tanto domésticos como silvestres. El signo característico de la neosporosis de las vacas es el aborto. En terneros y cachorros puede causar daños neurológicos.
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Vaccination is the only feasible way for appropriate prevention of Neospora caninum infection. The present in silico study was done to evaluate the physico-chemical properties and determine immunogenic epitopes of N. caninum SAG1 protein as a possible vaccine candidate. Web-based tools were used to predict physico-chemical properties, antigenicity, allergenicity, solubility, post-translational modification (PTM) sites, transmembrane domains and signal peptide, secondary and tertiary structures as well as intrinsically disordered regions, followed by identification and screening of potential linear and conformational B-cell epitopes and those peptides having affinity to bind mouse major histocompatibility complex (MHC) and cytotoxic T lymphocyte (CTL). The protein was stable in a test tube, had 319 residues with a molecular weight of 33.07 kDa, representing aliphatic index of 76.68 (thermotolerant) and GRAVY score of 0.031 (hydrophobic). There were 42 PTM sites and an N-terminally-located signal peptide in the sequence. Secondary structure comprised mostly by random coils, followed by strands and helices. Ramachandran plot of the refined model showed 71.7%, 24.9%, 3.0% and 0.4% residues in the favored, additional allowed, generously allowed and disallowed regions, correspondingly. Additionally, various potential B-cell (linear and conformational), CTL and MHC-binding epitopes were predicted for N. caninum SAG1. The findings of the present in silico study are a premise for vaccination strategies against neosporosis.
Neospora caninum has been implicated as a sporadic cause of abortion and perinatal deaths in sheep flocks globally. However, its significance as a reproductive pathogen for sheep in Australia remains unknown. The aims of this study were to (i) determine the seroprevalence of N. caninum in Australian breeding ewes and (ii) examine if natural exposure to N. caninum is associated with poor reproductive performance of primiparous ewes in southern Australia. Thirty flocks of primiparous ewes (aged 1–2 years old at lambing) from 28 farms in three states (Western Australia, South Australia and Victoria) were monitored between mating and lamb marking. Blood samples were also collected from multiparous mature ewes (aged 3 years or older) at each farm. Seroprevalence for anti-N. caninum IgG using indirect ELISA was determined for a subset of primiparous ewes that were predominantly determined to be pregnant and subsequently failed to rear a lamb (n = 1279) and randomly selected mature multiparous ewes with unknown reproductive status (n = 558). Neopsora caninum apparent seroprevalence was 0.16% (95% confidence interval 0.03%, 0.5%) in primiparous ewes, with seropositivity identified in two ewes from farms located in South Australia and Victoria. There was no evidence of seropositivity in mature ewes with apparent seroprevalence 0% (0%, 0.45%). These findings suggest that N. caninum infection was not widespread in primiparous ewes or mature multiparous ewes on these farms, and exposure to N. caninum infection was unlikely to explain abortion and perinatal mortalities observed for primiparous ewes.
Neosporosis is caused by the protozoan parasite Neospora caninum, an obligate intracellular parasite found in dogs and cattle as well as other species. Neospora can be transmitted vertically or horizontally, with both routes being vital to long‐term survival of the parasite. Neosporosis is primarily a disorder of the fetoplacental unit that occurs subsequent to maternal parasitemia resulting from either exogenous or endogenous infection. N. caninum infection causes abortion in both beef and dairy cattle. Abortion may occur from three months of gestation to term but typically occurs at five to six months of gestation. Definitive diagnosis of neosporosis is challenging and relies on numerous diagnostic techniques. Serology of the dam can aid in diagnosis of Neospora‐associated abortion. A number of approaches have been employed to control neosporosis in cattle herds. These include improving farm biosecurity, test and cull programs, test and exclude from breeding, and artificially inseminating with beef semen.
Neospora caninum causes disease of the muscle and nervous systems in canine pups and is known for producing disease in older dogs. We aimed to determine anti-N. caninum seroprevalence in healthy adult dogs from greater Sydney, New South Wales, Australia and summarise published reports of adult-onset of canine neosporosis. Indirect fluorescent antibody tests (IFAT) were used to detect anti-N. caninum IgG and compared to the value from an equivalent 1997 study. The N. caninum seroprevalence (anti-IgG, 1:50 serum dilution) was 14.1% (27/192; 95% CI: 9.1–19.0%) demonstrating no significant change compared to 1997 (12%; 18/150; 95% CI: 7.7–18.2%) (P = 0.58). A literature search identified 56 published cases of adult-onset canine neosporosis, most associated with neurological or myopathic signs (66.1%, 37/56) or cutaneous lesions (25.0%, 14/56). We confirm that a single IFAT N. caninum IgG titre has limited diagnostic value regardless of the cut-off because healthy adult dogs exhibit a range of titres.
Wild canids (wild dogs and European red foxes) cause substantial losses to Australian livestock industries and environmental values. Both species are actively managed as pests to livestock production. Contemporaneously, the dingo proportion of the wild dog population, being considered native, is protected in areas designated for wildlife conservation. Wild dogs particularly affect sheep and goat production because of the behavioural responses of domestic sheep and goats to attack, and the flexible hunting tactics of wild dogs. Predation of calves, although less common, is now more economically important because of recent changes in commodity prices. Although sometimes affecting lambing and kidding rates, foxes cause fewer problems to livestock producers but have substantial impacts on environmental values, affecting the survival of small to medium-sized native fauna and affecting plant biodiversity by spreading weeds. Canid management in Australia relies heavily on the use of compound 1080-poisoned baits that can be applied aerially or by ground. Exclusion fencing, trapping, shooting, livestock-guarding animals and predator calling with shooting are also used. The new Invasive Animals Cooperative Research Centre has 40 partners representing private and public land managers, universities, and training, research and development organisations. One of the major objectives of the new IACRC is to apply a strategic approach in order to reduce the impacts of wild canids on agricultural and environmental values in Australia by 10%. In this paper, the impacts, ecology and management of wild canids in Australia are briefly reviewed and the first cooperative projects that will address IACRC objectives for improving wild dog management are outlined.
Infection with Neospora caninum is regarded as a significant cause of abortion in cattle. Despite the economic impact of this infection, relatively little is known about the biology of this parasite. In this study, mini and microsatellite DNAs were detected in the genome of N. caninum and eight loci were identified that each contained repetitive DNA which was polymorphic among different isolates of this parasite. A multiplex PCR assay was developed for the detection of genetic variation within N. caninum based on length polymorphism associated with three different repetitive markers. The utility of the multiplex PCR was demonstrated in that it was able to distinguish amongst strains of N. caninum used as either vaccine or challenge strains in animal vaccination experiments and that it could genotype N. caninum associated with naturally acquired infections of animals. The multiplex PCR is simple, rapid, informative and sensitive and should provide a valuable tool for further studies on the epidemiology of N. caninum in different host species.
A recently described PCR test for the identification of Neospora caninum and Toxoplasma gondii has been further developed and optimized in view of its practicability for routine diagnostic application. The N. caninum-specific PCR was adapted to the diagnostic operating standard of the T. gondii-specific PCR in that the uracil DNA glycosidase system was introduced, which eliminates potential carry-over contaminations of amplified target DNA from previous reactions. Furthermore, both PCR tests were optimized by including a DNA hybridization immunoassay based on the use of the commercially available Gen-eti-k DEIA kit. This assay allowed highly sensitive and specific detection of respective DNA amplification products and thus substantially facilitated the reading and interpretation of the test results.
Dogs were investigated to determine if they are definitive hosts of Neospora caninum. Four dogs were fed N. caninum tissue cysts in infected mouse tissue, and two negative control dogs were fed uninfected mouse tissue. Dog faeces were examined daily for 30 days using a sucrose flotation technique. Three challenged dogs shed spherical to subspherical unsporulated oocysts, measuring 10 to 11 microns in diameter. Oocysts sporulated within 3 days and contained two sporocysts, each with four sporozoites. Outbred, inbred, and gamma-interferon knockout mice were inoculated with canine faecal extracts and monitored for evidence of neosporosis using a variety of morphologic, immunohistologic, serologic, and genetic analyses. Mice that received faeces from each dog observed to shed oocysts were demonstrated to have neosporosis by two or more techniques. One mouse was demonstrated to be infected with N. caninum by immunohistochemistry, ultrastructural analysis, and a species-specific PCR test. No evidence of neosporosis was observed in control animals. Based on this study, dogs are a definitive host of Neospora caninum.
A previously described monoclonal antibody (MAb)-based competitive-inhibition enzyme-linked immunosorbent assay (cELISA) was
modified to optimize performance, and the assay was validated in various defined cattle populations for detection of serum
antibody to Neospora caninum, a major cause of bovine abortion. Modifications to the cELISA included capturing nativeN. caninum antigen with a parasite-specific MAb (MAb 5B6-25) and directly conjugating the competitor MAb (MAb 4A4-2), with both MAbs
binding different epitopes of a conserved, immunodominant 65-kDa tachyzoite surface antigen. The assay was validated using
three serum sets, a “gold standard” set of 184 cow sera defined by fetal histopathology and N. caninum immunohistochemistry and by maternal N. caninum indirect fluorescence assay (IFA) at a 1:200 serum dilution, a relative standard set of 330 cow sera defined by IFA alone,
and a set of 4,323 cow sera of unknown N. caninum status. A test cutoff of 30% inhibition was identified. The diagnostic sensitivity was 97.6%, and diagnostic specificity
was 98.6% for the gold standard abortion-defined sera. The diagnostic sensitivity was 96.4%, and diagnostic specificity was
96.8% for the relative standard IFA-defined sera. Testing of the 4,323 bovine sera of unknown N. caninum status revealed a distinct bimodal distribution and steep sigmoid frequency curve with only 1.8% of samples within 5% of
the test cutoff, indicating a sharp discrimination between test-positive and test-negative samples. In summary, the modified
N. caninum cELISA provided a simple, rapid, and versatile method to accurately identify N. caninum infection status in cattle using a single cutoff value.
Neospora caninum is a protozoan parasite of animals, which before 1984 was misidentified as Toxoplasma gondii. Infection by this parasite is a major cause of abortion in cattle and causes paralysis in dogs. Since the original description of N. caninum in 1988, considerable progress has been made in the understanding of its life cycle, biology, genetics and diagnosis. In this article, the authors redescribe the parasite, distinguish it from related coccidia, and provide accession numbers to its type specimens deposited in museums.
Scarce information is available about Neospora caninum oocysts and sporozoites, in part because only small numbers of oocysts have typically been produced by experimentally infected dogs. We hypothesized that I reason for low experimental production of oocysts is that dogs have been fed tissues from experimentally infected mice instead of tissues from cattle (which are natural intermediate hosts of N. caninum). In this study, 9 dogs were fed tissues from N. caninum-infected calves, and oocyst production was compared with 6 dogs that were fed infected mouse carcasses. The number of oocysts produced by dogs that ingested infected calf tissues (mean = 160,700) was significantly greater (P = 0.03) than the number of oocysts shed by dogs that ingested infected mice (mean = 5,400). The second goal of our experiment was to demonstrate cyclical oral transmission of N. caninum between dogs and cattle. As few as 300 oocysts were used to successfully infect calves, and tissues from these calves induced patent infections in 2 of 3 dogs; oocysts from I of these dogs were administered to another calf, and tissues from this calf subsequently induced a third dog to shed oocysts. Oocysts were confirmed to be N. caninum using a species-specific polymerase chain reaction technique. In addition, sporulated oocysts were used to recover N. caninum in vitro after digestion in an acid-pepsin solution and inoculation of cell monolayers.
Four captive-raised coyote pups consumed tissues from Neospora caninum-infected calves. Faeces were examined from 4 days before to 28 days after infection. One pup shed N. caninum-like oocysts, which tested positive for N. caninum and negative for Hammondia heydorni using PCR tests. Coyotes are the second discovered definitive host of N. caninum, after dogs. In North America, the expanding coyote ranges and population increase the probability of contact with domestic livestock. To reduce the risk of transmission of N. caninum to intensively farmed cattle, we recommend protection of feedstuffs using canid-proof fences, and careful disposal of dead stock.
Neospora caninum infection is a common cause of bovine abortion. One method by which cattle can acquire infection is through ingestion of oocysts; however, this has not yet been proved to cause transplacental infection or abortion. In this study, 19 cows, pregnant between 70 and 176 days, were administered 1500 to 115,000 oocysts through an esophageal tube. Seventeen of the cows became seropositive, indicating acquisition of infection, whereas 8 negative control cows remained seronegative (P < 0.001). Offspring were examined using serology, histology, immunohistochemistry, parasite isolation, and polymerase chain reaction (PCR). Six offspring were infected and 1 of them was aborted. The aborted fetus had typical lesions and positive immunohistochemistry and PCR for N. caninum. All 6 cows with infected offspring had continuously rising antibody titers, whereas 10 of 11 infected cows with uninfected offspring had falling titers after an early apex. The risk of transplacental transmission was increased by later exposure times during gestation and by the dose of oocysts (P < 0.01 for the 2 combined variables). The lowest dose of oocysts, when administered after the 160th day of gestation, caused transplacental infection in 1 of 2 animals. This study demonstrates that infection with N. caninum oocysts can cause transplacental transmission and abortion in cattle.
Neospora caninum is an obligate intracellular protozoan parasite that causes abortion in cattle. It is normally found as a latent infection
controlled by a T-helper-cell type 1 response involving CD4+ cytotoxic T cells and gamma interferon. Cattle may be infected by two different routes: transplacentally as a result of activation
of the latent infection in the mother causing congenital infection or abortion and by ingestion of oocysts, which, if it occurs
during gestation, can also result in abortion. Here, for the first time, we establish proof that live vaccination protects
against fetal death, whereas immunization using whole-tachyzoite lysate in different adjuvants fails to protect against fetal
death. Strong antibody responses were induced in all the vaccinated groups, and the quality and magnitude of these responses
were similar in the live- and the lysate-vaccinated groups. In contrast, only the group immunized with live tachyzoites had
strong cellular and gamma interferon responses prior to challenge, and these responses correlated with protection against
fetopathy. These results suggest that a cellular immune response may be important in the mechanisms involved in protection
against N. caninum-associated abortions.
Neospora caninum is a protozoan parasite of animals. Until 1988, it was misidentified as Toxoplasma gondii. Since its first recognition in dogs in 1984 and the description of the new genus and species Neospora caninum in 1988, neosporosis has emerged as a serious disease of cattle and dogs worldwide. Abortions and neonatal mortality are a major problem in livestock operations, and neosporosis is a major cause of abortion in cattle. Although antibodies to N. caninum have been reported, the parasite has not been detected in human tissues. Thus, the zoonotic potential is uncertain. This review is focused mainly on the epidemiology and control of neosporosis in cattle, but worldwide seroprevalences of N. caninum in animals and humans are tabulated. The role of wildlife in the life cycle of N. caninum and strategies for the control of neosporosis in cattle are discussed.
The development of a novel nested polymerase chain reaction is described and used for detecting the presence of Neospora caninum and Hammondia heydorni DNA in DNA extracted from feral rodent tissues. A unique strategy was used for design of an assay that could be adapted for detecting DNA from more than one member of Toxoplasmatinae simultaneously with a minimal number of additional steps. The level of sensitivity described for this assay is comparable to real time-PCR and other nested PCR assays. Twenty-eight of 104 feral mice tested positive for N. caninum in at least one tissue (the brain, heart or liver) studied. In this study, eight instances are reported where the brain tested negative to N. caninum while at least one other tissue was positive. This suggests that prior studies, which screened only the brain, describe prevalence levels that are under-represented. None of 54 mouse brains tested positive for H. heydorni DNA. This suggests that mice are rarely infected by H. heydorni although this hypothesis needs to be explored further. Data obtained in the current study suggest that N. caninum is a common parasite of feral rodents which may be important in the epidemiology of the disease.
In stomach contents of 530 dingoes (Canis familiaris dingo) in south east Australia, 89.3% of feed, by occurrence, was large and medium-sized marsupials (Wallabia, Macropus, Pseudocheirus and Trichosurus). Of 26 dingoes with sheep or cattle remains in the stomach, 11 had eaten it as carrion, judging from the presence of maggots, and 5 of those had obtained it from carcasses used as bait for the traps. There was 4% of feral pig, 0.3% of horse and 7.8% of rabbit, which are all regarded as pests. There were 26 species of prey altogether. Of the 25 other species caught in the traps, over 20 were protected wildlife.
The diet of two populations of dingoes, from adjacent areas different in topography and altitude, from
1969 to 1974, were similar. The remains of native mammals were found in over 90% of the scats, and
Wallabia bicolor was the most important single prey species in both areas. The high frequency of large
native species in this and other studies of dingoes' diet suggested that dingoes may be essentially
predators of the larger native species. The mammalian composition of the diet varied significantly
between May-October and November-April; this reflected a change in the hunting strategy ofthe dingo,
as an outcome of behavioural necessity rather than a change in the relative abundances of prey species.
Concurrent with an increase in the dingo population, the composition of the diet changed between 1972
and 1974, with an increased concentration on larger prey species in the later years; this also indicated a
change in hunting strategy. Large prey species provide potentially more biomass per unit kill; and this
change in hunting strategy may be a behavioural mechanism for buffering dingo populations against
either increases in their own population or decreases in those of their prey.
Oocysts of Neospora caninum were collected from the faeces of a dog fed mouse brains containing tissue cysts of the NC-beef strain of N. caninum. Sporulated oocysts were spherical to subspherical, and were 11.7×11.3 μm. The length/width ratio was 1.04. No micropyle or oocyst residuum was present. Polar granules were not present, although occasionally tiny refractile granules were seen among sporocysts. Sporocysts were ellipsoidal, did not contain a Stieda body, and were 8.4×6.1 μm. The length/width ratio for sporocysts was 1.37. A spherical or subspherical sporocyst residuum was present, and was composed of a cluster of small, compact granules of 4.3×3.9 μm, or was represented by many dispersed granules of similar size. Sporozoites were elongate and 7.0–8.0×2.0–3.0 μm in situ. No refractile bodies were present and the nucleus was centrally or slightly posteriorly located. The features of the oocyst of N. caninum are similar to those of Hammondia heydorni oocysts from dog faeces and Toxoplasma gondii and Hammondia hammondi oocysts from cat faeces.
The transmission and control of Neospora caninum infection in dairy cattle was examined using deterministic and stochastic models. Parameter estimates were derived from recent studies conducted in the UK and from the published literature. Three routes of transmission were considered: maternal vertical transmission with a high probability (0.95), horizontal transmission from infected cattle within the herd, and horizontal transmission from an independent external source. Putative infection via pooled colostrum was used as an example of within-herd horizontal transmission, and the recent finding that the dog is a definitive host of N. caninum supported the inclusion of an external independent source of infection. The predicted amount of horizontal transmission required to maintain infection at levels commonly observed in field studies in the UK and elsewhere, was consistent with that observed in studies of post-natal seroconversion (0.85-9.0 per 100 cow-years). A stochastic version of the model was used to simulate the spread of infection in herds of 100 cattle, with a mean infection prevalence similar to that observed in UK studies (around 20%). The distributions of infected and uninfected cattle corresponded closely to Normal distributions, with S.D.s of 6.3 and 7.0, respectively. Control measures were considered by altering birth, death and horizontal transmission parameters. A policy of annual culling of infected cattle very rapidly reduced the prevalence of infection, and was shown to be the most effective method of control in the short term. Not breeding replacements from infected cattle was also effective in the short term, particularly in herds with a higher turnover of cattle. However, the long-term effectiveness of these measures depended on the amount and source of horizontal infection. If the level of within-herd transmission was above a critical threshold, then a combination of reducing within-herd, and blocking external sources of transmission was required to permanently eliminate infection.
Neospora caninum is a cyst-forming coccidian parasite which is now recognised as a major cause of abortion and neonatal mortality in cattle and other livestock. This study describes the primary DNA structure of the transcribed spacer region of the rDNA of N. caninum. Of importance is that the sequence data generated have been used to develop a species-specific PCR test for N. caninum DNA, which will prove valuable in epidemiology studies on neosporosis. Copyright (C) 1996 Australian Society for Parasitology.
A total of 1,554 dogs from 5 countries on 3 continents were tested for antibodies to Neospora caninum using an indirect fluorescent antibody test. In Australia, overall, 42/451 (9%, 95% confidence interval [CI] 6-12%) dogs were seropositive (Melbourne 11/207 [5%, 95% CI 2-9%]; Sydney 18/150 [12%, 95% CI 7-18%]; Perth 13/94 [14%, 95% CI 8-22%]). Antibodies to N. caninum were also detected in dogs in South America (Uruguay [20%, 95% CI 16-24%, n = 414]) and sub-Saharan Africa (Tanzania [22%, 95% CI 12-36%, n = 49]). In contrast, only 1 of 500 dogs tested from the Falkland Islands and none of 140 dogs from Kenya was seropositive. Of wild canids, 1/54 (2%, 95% CI 0-10%) British foxes and 15/169 (9%, 95% CI 5-14%) Australian dingoes had antibodies to N. caninum.
The association of Neospora caninum infections with cattle families was examined in a dairy cattle herd with sporadic abortions using three different serological tests. Cattle seropositive for N. caninum clustered in six families, three of which encountered abortions. In absence of age-related differences in the N. caninum seroprevalence, the family association of N. caninum infection indicated that congenital infection represented the predominant route of transmission in this herd. Fourteen (93%) out of 15 descendants of 10 seropositive cows were seropositive themselves. Only one female calf of a seropositive cow remained seronegative and gave birth to a calf which was tested seronegative again. Only one seronegative cow that had two seronegative descendants also gave birth to one seropositive calf. This was the only indication for potential postnatal transmission that occurred in the herd. The results of this study suggest that the N. caninum-infection can be maintained over several generations at a nearly constant prevalence level, apparently without a need for dispersion by an definitive host.
This study compared the biological and genetic properties of a bovine (NC-SweB1) and a canine (NC-Liverpool) isolate of Neospora caninum. A mouse model for CNS infection demonstrated marked differences in pathogenicity between the isolates. NC-Liverpool induced severe clinical signs of neosporosis in 57/58 mice including discoordinated movement, hindlimb paralysis and coat ruffling with severe weight loss. In contrast NC-SweB1 induced similar but less severe symptoms in a much smaller proportion of mice over the same time-period. Statistically significant differences were observed between the isolates in the response (mean weight loss) of mice through time to the different doses inoculated. Histopathological effects on brain tissue reflected the isolate-based differences described above. NC-Liverpool infection resulted in intense inflammatory infiltrates and highly necrotic lesions whereas NC-SweB1 induced a milder meningoencephalitis. Passage in cell-culture over a period of 14 months did not affect the pathogenicity of NC-Liverpool. Immunoblots showed that antibodies to N. caninum appeared earlier in mice inoculated with NC-Liverpool than with NC-SweB1. Finally, RAPD-PCR analysis of NC-Liverpool DNA generated profiles distinct from that observed with DNA from NC-SweB1 or Toxoplasma gondii. In summary this study provides evidence for significant biological and genetic differences between 2 isolates of N. caninum.
Two mixed-breed littermate dogs were fed mouse brains containing tissue cysts of the NC-beef isolate of Neospora caninum. Both dogs excreted N. caninum oocysts in their feces. Dog 1 which was given methylprednisolone acetate (MPA) prior to ingesting tissue cysts, excreted oocysts on days 5 to 10 inclusive and on day 17 after ingesting tissue cysts. Dog 1 had a serum antibody titer of 1:200 in the indirect fluorescent antibody test (IFAT) 35 days after it was fed tissue cysts. Dog 2, which was not treated with MPA, excreted oocysts on Day 6 and Day 9 after ingesting tissue cysts. Antibodies to N. caninum were not found in a 1:25 dilution of serum on any examination period for Dog 2 during the study. Neospora caninum was not found in the tissues of either dog by histological or immunohistochemical means following necropsy 42 days after being fed tissue cysts. The identity of the oocysts excreted in the feces of the dogs was confirmed by mouse inoculation studies.
Hammondia heydorni is thought to be a non-pathogenic coccidian parasite of dogs that is closely related to Neospora caninum, an important parasite of cattle and dogs. Oocysts of these two species are morphologically indistinguishable from each other. A population of 2240 dogs in the Czech Republic was screened for the presence of H. heydorni/N. caninum oocysts and five (0.22%), represented by five of 3135 faecal samples (0.16%), were positive. The internal transcribed spacer 1 region of the rRNA gene (ITS1) from two isolates were cloned and the DNA sequences were identical with those of the ITS1 of H. heydorni. Based on the rRNA sequences available for H. heydorni and related coccidia, the primer pair JS4-JS5 was designed to amplify the 3' end of the small subunit (SSU) rRNA gene and ITS1 of H. heydorni. When tested on DNA extracted from a variety of parasites, the primers amplified a specific 267 bp fragment in our isolates only. The presence of DNA equivalent to 10 oocysts was sufficient for the amplification of the ITS1. We present a PCR-based diagnostic method as the only fast and reliable method for the diagnosis of H. heydorni in dogs.
To isolate Neospora caninum from a congenitally infected calf.
A calf was obtained from a N. caninum infected dam maintained in a dairy herd of Holstein-Friesian cattle located on the south coast of NSW near Nowra. The calf was euthanased and samples collected for serology and pathology. Samples of brain and spinal cord of the calf were homogenised and injected into immunocompromised mice in an attempt to recover protozoa by in vivo culture. Sequential passage of brain homogenate through IFNgammaPKO mice was performed and tissue culture flasks were inoculated with brain homogenate. Parasites were identified by electron microscopy and DNA sequencing. The antigen profile of the isolate was analysed using Western blotting. Pathogenicity was examined in BALB/c mice and transmission of the parasite during pregnancy was examined in Qs mice.
The calf was seropositive for N. caninum and histopathological examination of sections of cerebrum identified lesions consistent with a very mild infection with N. caninum. The parasites isolated using tissue culture were identified as N. caninum, based on the sequence of the ribosomal DNA and electron microscopy. The antigen profile of the new isolate was similar to that of the NC-Liverpool isolate, but quite different from that of Toxoplasma gondii. In BALB/c mice inoculated with the new isolate, severe clinical signs developed in only three of ten infected mice, compared with six of ten mice infected with NC-Liverpool. Mild to moderate nonsuppurative encephalitis was observed in BALB/c mice infected with the new isolate, compared with mice infected with NC-Liverpool, that developed severe nonsuppurative encephalitis. Transplacental transmission of the isolate arising from an acute infection during pregnancy occurred in about 87% of pups.
This is the first isolation of bovine Neospora caninum in Australia. This isolate, called NC-Nowra, appears to be a less virulent form and may prove to be a suitable candidate for vaccine development.
The humoral and cell-mediated immune responses of pregnant cattle and their fetuses were examined at intervals after infection with Neospora caninum tachyzoites at mid-gestation (day 140). All cattle seroconverted and interferon gamma was detected in supernatants of peripheral blood mononuclear cells stimulated with specific antigen. At day 14 post-inoculation (pi), specific cell proliferation responses were detected in the lymph node draining the site of inoculation and in the uterine lymph node. The peak response was recorded in the majority of maternal lymph nodes by day 28 pi and cells from the maternal retropharyngeal lymph node, which in part drains the central nervous system, showed no specific activity to N. caninum until day 42 pi. This changing pattern of immune responsiveness may reflect parasite invasion and development within different host tissues. Fetal lymph node cells showed mitogen responsiveness from day 14 pi (day 154 of gestation) and also showed N. caninum-specific cell proliferation and interferon-gamma responses by day 28 pi (day 168 of gestation). At day 42 pi, specific cell-mediated immune responses were not apparent; however, N. caninum-specific fetal IgG and IgM antibodies were detected.
Results of molecular determination of a dog isolate of Neospora caninum in the Czech Republic are presented. Colorless bisporocystic oocysts measuring 10-13 micro m x 10-11 micro m were recovered from feces and used for DNA isolation. A diagnostic PCR procedure using previously described molecular methods was performed to determine the species. The N. caninum species-specific primers based on the Nc 5 region produced a positive result, while primers specific for Hammondia heydorni rDNA internal transcribed spacer 1 (ITS1) was negative. Sequencing and phylogenetic comparison of ITS1 rDNA and the D2 domain of the large subunit rDNA (D2 LSU) determined our isolate to be N. caninum. Phylogenetic analysis of closely related genera Toxoplasma, Neospora and Hammondia based on ITS1 and D2 LSU robustly distinguished three clades: (i). Toxoplasma gondii + Hammondia hammondi, (ii). N. caninum + Neospora hughesi, and (iii). H. heydorni. Based on phylogenetic relationships we propose three acceptable suggestions to solve the problem of taxonomy of these genera.
To determine the contribution of Neospora caninum to abortions on a dairy farm in NSW (Australia), determine the mode of transmission and develop and trial a control option for infection.
Two whole herd bleeds were conducted 12 months apart and the association between serological status and abortion events were calculated for a number of bovine abortifacients. Family trees were constructed for N. caninum seropositive cattle in the herd. Some N. caninum seropositive cows were culled from the herd and no female offspring was retained from seropositive cows.
At the first whole-herd bleed in December 2002 a seroprevalence of 10.2% for N. caninum infection was detected. Cows with N. caninum infection were 13 times more likely to abort than uninfected ones. Seventy-five percent of seropositive animals in the herd were related, suggesting a high degree of congenital infection/transmission. Only 15% of infections were likely to be postnatally acquired. Selective culling of seropositive cows and not breeding from them reduced the number of seropositive animals. Only one newly sero-converted cow was detected at the second whole-herd bleed 12 months later.
Seroepidemiological approaches were able to establish a high degree of association between N. caninum infection and low-level abortion in the dairy herd. Vertical transmission of infection was the predominant mode of infection and hence control efforts aimed at selectively culling seropositive animals from the herd were highly successful in reducing the level of infection.
Faecal samples of 24,089 dogs were examined coproscopically in two veterinary laboratories in Germany between March 2001 and October 2004. In 47 dogs, oocysts of 9-14 microm size were found. Their morphology was similar to those of Hammondia heydorni and Neospora caninum. Samples of 28 of these dogs were further examined by inoculation into gerbils: seven isolates induced a specific antibody response against antigens of N. caninum NC-1 tachyzoites. This response suggests that the isolates contained N. caninum. In addition to H. heydorni (12 times isolated), Toxoplasma gondii occysts (twice) and Hammondia hammondi oocysts (twice) were observed in dog faeces. The latter findings suggest that coprophagia with a subsequent intestinal passage by dogs plays a role in the dissemination of coccidian parasites for which cats are definitive hosts. Five of the seven N. caninum (NC-GER2, NC-GER3, NC-GER4, NC-GER5, NC-GER6) and the two T. gondii isolates (TG-dgGER1, TG-dgGER2) were successfully passaged into cell culture and are now available for detailed characterization. In contrast to oocysts of other parasites, N. caninum oocysts were predominantly found between January and April (Fisher exact; P=0.038). In the sera of dogs shedding N. caninum, no reactions against the immunodominant antigens with apparent molecular weights of 19, 29, 30, 33 and 37 kDa of N. caninum tachyzoites were observed 3-5 weeks after shedding. However, the animals recognized a 152-kDa N. caninum antigen. Compared with those identified as H. heydorni, T. gondii or H. hammondi, N. caninum oocyst isolates were significantly smaller in length with the 75th percentiles <or=10.7 microm when measured in concentrated sucrose solution and smaller length-width ratios with the 75th percentiles <or=1.06. It may thus be possible to develop criteria for a preliminary identification of N. caninum in dog faeces based on the oocyst morphology.
A commercially available competitive enzyme-linked immunosorbent assay (cELISA, VMRD) was validated for the detection of Neospora caninum antibodies in the serum of dogs, using as a reference test an indirect fluorescent antibody test (IFAT, Fuller). A partial verification approach was used. A total of 618 dogs were screened with cELISA and a subset of positive and negative sera (n=237) were then tested with IFAT. Naïve relative sensitivity (SE(nv)) and naïve relative specificity (SP(nv)) of cELISA were calculated and then corrected (SE(corr); SP(corr)) for studies with partial validation. Results showed a SE(nv) of 72% and a SP(nv) of 89.3%; corrected estimates showed a SE(corr) of 47% and a SP(corr) of 96%. ROC analysis showed that the cutoff recommended by the manufacturer (30%) corresponded to the highest naïve sensitivity (72%) combined with a good naïve specificity (90%) of cELISA. Corrected estimates of SE and SP for partial verification method revealed that SE of the cELISA is lower and SP is higher than naïve estimates. The results suggest to use this test for confirmation of a clinical suspicion of neosporosis, and to use some techniques for adjustment of misclassification in prevalence and risk-factor studies.
The protozoan parasite Neospora caninum is a major pathogen of cattle and dogs, being a significant cause of abortion in cattle in many countries. It is one of the most efficiently transmitted parasites, with up to 90% of cattle infected in some herds. The pathogenesis of abortion due to Neospora is complex and only partially understood. Losses occur after a primary infection during pregnancy but more commonly as the result of recrudescence of a persistent infection during pregnancy. Parasitaemia is followed by invasion of the placenta and fetus. It is suggested that abortion occurs when primary parasite-induced placental damage jeopardises fetal survival directly or causes release of maternal prostaglandins that in turn cause luteolysis and abortion. Fetal damage may also occur due to primary tissue damage caused by the multiplication of N. caninum in the fetus or due to insufficient oxygen/nutrition, secondary to placental damage. In addition, maternal immune expulsion of the fetus may occur associated with maternal placental inflammation and the release of maternal pro-inflammatory cytokines in the placenta. Thus N. caninum is a primary pathogen capable of causing abortion either through maternal placental inflammation, maternal and fetal placental necrosis, fetal damage, or a combination of all three. The question of how N. caninum kills the fetus exposes the complex and finely balanced biological processes that have evolved to permit bovine and other mammalian pregnancies to occur. Defining these immunological mechanisms will shed light on potential methods of control of bovine neosporosis and enrich our understanding of the continuity of mammalian and protozoal survival.
To determine the performance characteristics of an Institut Pourquier (IP) enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies against Neospora caninum in bovine milk and subsequent determination of the prevalence of N. caninum infection in New South Wales (NSW) dairy cattle.
Matching serum and milk samples from 93 cattle were assayed in two commercially available ELISAs for the detection of anti-N. caninum antibodies. Serum test results of one ELISA (IDEXX) were used to determine the N. caninum infection status of the cattle. Optimised cut-off values for the IP ELISA using milk samples were determined by two-graph receiver operating characteristic (TG-ROC) analysis and then applied to a representative sample of 398 milk samples from dairy herds around NSW.
When this ELISA was applied to a representative collection of 398 milk samples from dairy cattle across NSW it demonstrated a 21.1% prevalence of N. caninum infection in those cattle. From the TG-ROC analysis an IP ELISA protocol was derived which suggested a cut-off threshold that would allow milk testing with 97% sensitivity and specificity, respectively, relative to serum testing.
The prevalence of N. caninum in NSW dairy cattle was higher than previously believed. When used on individual milk samples this ELISA demonstrated high sensitivity and specificity and so could be used to accurately identify N. caninum infection. TG-ROC analysis of the IP ELISA optimised the protocol and prescribed cut-off values enabling the ELISA to be used for the screening of N. caninum antibodies in the milk of dairy cattle.
Neospora caninum is a world-wide parasite that causes neuromuscular disorders in dogs and bovine abortion. Biological diversity among isolates has been proved in both in vivo and in vitro studies. In contrast, little is known about the genetic diversity of this parasite. Microsatellite sequence analysis constitutes a suitable tool that has been used for the genetic analysis of other apicomplexan parasites. In this report, we describe the identification and analysis of 13 microsatellite loci from N. caninum DNA sequences deposited in public databases, which were evaluated with the use of 9 isolates grown in vitro. One microsatellite was monomorphic, and the remaining 12 loci exhibited 3 to 9 separate alleles. Multilocus analysis showed that each of the 9 isolates investigated here displayed a unique profile and revealed no association between the genetic similarity and host or geographic origin. The multilocus analysis approach described here might nevertheless provide the powerful tool needed to study the genetic complexity of N. caninum and the molecular epidemiology of neosporosis.
The dog is a definitive host of the protozoan parasite Neospora caninum, and in many parts of the world, infection is relatively common as determined by serology. Reported seroprevalences usually range from 0 to 20 per cent, however, reports of clinically affected dogs are infrequent. Affected dogs are generally less than six months old and predominantly have signs of an ascending hindleg paralysis, with the associated lesions of polyradiculoneuritis and granulomatous polymyositis. Although any organ may be affected, infections are more common in the central nervous system, muscles, lungs and skin. Ante-mortem diagnosis is difficult but serology and cytology can aid diagnosis. The diagnosis can be confirmed by histology, immunohistochemistry, the use of molecular techniques on biopsy material, or on post-mortem examination. Neospora caninum oocysts are rarely found in faeces and must be differentiated from oocysts of related coccidians such as Hammondia heydorni and Toxoplasma gondii. Hammondia heydorni can cause diarrrhoea in immunosuppressed dogs. Neosporosis should be suspected in young pups with an ascending paralysis of the hindlegs. Treatment with clindamycin and potentiated sulphonamides may be useful in cases where muscular atrophy and fibrosis are absent. Feeding of raw meat is a potential risk factor for infection of dogs and should be discouraged.
The ecology of the dingo in north-eastern
- J D Robertshaw
- R H Harden
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