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Immunodiagnostic tools for Taeniasis
Abstract
Most diagnostic work conducted on the Taenia species zoonoses has been carried out on the larval stage of Taenia solium in man, reflecting the relative severity of the pathology caused by this stage of that organism. This review will, however, concentrate on the immunodiagnosis of the adult intestinal stages of these parasites in humans. Diagnosis of T. solium will be examined in most detail because of the relative importance of this parasite but relevant work from other cestodes of man and animals will also be discussed. In addition both classical and molecular approaches to diagnosis will be briefly covered. There have been a number of advances in immunodiagnosis of taeniasis over recent years that have improved both diagnostic sensitivity and specificity. Techniques for the detection of Taenia specific coproantigens in human taeniasis infections have been shown to more than double the numbers of T. solium cases accurately diagnosed in epidemiological studies. More recently, work on the serological diagnosis of T. solium have led to the development of a sensitive and specific enzyme linked immuno-transfer blot for the detection of species and stage specific circulating antibodies to adult worm excretory-secretory antigens. Work is ongoing to further improve these assays.
... It has both low sensitivity and specificity and the intermittent nature of egg excretion leads to underestimation of taeniasis prevalence [43,44]. In addition, if a massive discharge of eggs occurs after destrobilisation, the eggs may be absent from the stool for up to several weeks thereafter [45]. The copro Ag-ELISA technique depends on the detection of parasite specific antigens in host faeces. ...
... If these products are associated with parasite metabolism they should be present independently of parasite reproductive material (i.e. Taeniid eggs or proglottides) [45,46]. Copro Ag-ELISA thus has a sensitivity that is 2-10 times higher than that of microscopy, which could explain the difference in the two prevalences [45]. ...
... Taeniid eggs or proglottides) [45,46]. Copro Ag-ELISA thus has a sensitivity that is 2-10 times higher than that of microscopy, which could explain the difference in the two prevalences [45]. However, we are cautious in interpreting the high proportion on copro Ag-ELISA because the test cannot differentiate between T. solium and Taenia saginata infections, as it is only genus specific [45]. ...
Background
Intestinal helminth infections are among the most common infections worldwide and have a negative impact on the health, education, nutrition and economic development of affected populations. This study aimed to estimate the prevalence of intestinal helminthiasis, including T . solium taeniasis, using a large-scale community-based study in Chiparamba area of Chipata District in the Eastern province of Zambia.
Methods/Principal findings
A cross-sectional study was conducted between June 2019 and December 2022 in a rural community of 25 randomly selected villages known to be at risk for T . solium infection. Stool samples were examined for intestinal helminths using the formol-ether concentration technique and further tested for taeniasis by copro antigen-ELISA (copro Ag-ELISA). Descriptive statistical analyses were conducted, and associations between the disease prevalence of active infections and individual- and village-level variables were determined using the chi-square or Fisher’s exact test. Predictors of an individual being positive for either taeniasis or other soil-transmitted helminths were determined using binary logistic regression. A total of 2762 stool samples were examined. One hundred ninety-five (7.1%) tested positive for at least one helminthic parasite on microscopy, with hookworm being the most frequent 84 (3.0%), followed by S . mansoni , 66 (2.4%). For taeniasis, 11 (0.4%) participants were positive for Taenia spp. microscopically, while 241 (8.7%) tested positive via copro Ag-ELISA. On bivariate analysis, male sex was significantly associated with the prevalence of intestinal parasites ( p = 0.012) but not with that of taeniasis based on copro Ag-ELISA results. Village level differences were significant for infection with intestinal helminths as well as for taeniasis positivity on copro Ag-ELISA ( p <0.001).
Conclusion
Intestinal helminths, including T . solium taeniasis, are prevalent in Chiparamba area of Chipata district in the eastern province of Zambia, supporting the clear need for further targeted public health interventions for surveillance and control.
... eggs were visualized in stool or the CoAg-ELISA test produced an ODR greater than 20%. We choose to use ODR > 20% as a case definition in this analysis to reduce the rate of false positives due to non-specific binding and cross-reaction with other Taenia spp., which may occur at low ODR values [21,22]. ...
... There are a few additional limitations to our study that must be noted. First, while the CoAg-ELISA is the most sensitive and specific diagnostic available to detect human taeniasis [22], cross-reaction with other Taenia species and non-specific binding of the CoAg-ELISA assay with host factors are known to occur [21,22]. Therefore, it is possible that our use of the CoAg-ELISA assay for T. solium tapeworm detection could have allowed for false positive diagnoses, which may have diluted the observed spatial relationship. ...
... There are a few additional limitations to our study that must be noted. First, while the CoAg-ELISA is the most sensitive and specific diagnostic available to detect human taeniasis [22], cross-reaction with other Taenia species and non-specific binding of the CoAg-ELISA assay with host factors are known to occur [21,22]. Therefore, it is possible that our use of the CoAg-ELISA assay for T. solium tapeworm detection could have allowed for false positive diagnoses, which may have diluted the observed spatial relationship. ...
Background
Taenia solium, a parasite that affects humans and pigs, is the leading cause of preventable epilepsy in the developing world. Geographic hotspots of pigs testing positive for serologic markers of T. solium exposure have been observed surrounding the locations of human tapeworm carriers. This clustered pattern of seropositivity in endemic areas formed the basis for geographically targeted control interventions, which have been effective at reducing transmission. In this study, we further explore the spatial relationship between human tapeworm carriers and infected pigs using necroscopic examination as a quantitative gold-standard diagnostic to detect viable T. solium cyst infection in pigs.
Methodology/Principal findings
We performed necroscopic examinations on pigs from 7 villages in northern Peru to determine the number of viable T. solium cysts in each pig. Participating humans in the study villages were tested for T. solium tapeworm infection (i.e., taeniasis) with an ELISA coproantigen assay, and the distances from each pig to its nearest human tapeworm carrier were calculated. We assessed the relationship between proximity to a tapeworm carrier and the prevalence of light, moderate, and heavy cyst burden in pigs. The prevalence of pig infection was greatest within 50 meters of a tapeworm carrier and decreased monotonically as distance increased. Pigs living less than 50 meters from a human tapeworm carrier were 4.6 times more likely to be infected with at least one cyst than more distant pigs. Heavier cyst burdens, however, were not more strongly associated with proximity to tapeworm carriers than light cyst burdens.
Conclusion/Significance
Our study shows that human tapeworm carriers and pigs with viable T. solium cyst infection are geographically correlated in endemic areas. This finding supports control strategies that treat humans and pigs based on their proximity to other infected individuals. We did not, however, find sufficient evidence that heavier cyst burdens in pigs would serve as improved targets for geographically focused control interventions.
... Diagnosis of taeniasis is mainly based on the search for parasitic material in feces [30]. Several tests have been developed, and each has its own advantages and disadvantages (Table 1). ...
... In addition, the specificity of Copro-Ag ELISA coproantigen enzyme-linked immunosorbent assay; LAMP loop-mediated isothermal amplification; PCR polymerase chain reaction coproscopic methods is limited at the genus level because the eggs of these tapeworms are identical under light microscopy [1]. This is particularly relevant given the risks associated with T. solium infection [30]. Parasitological identification of human adult intestinal taeniids to species level relies on the recovery of gravid proglottids or scolices. ...
... Parasite coproantigens constitute specific products in the feces of the host that it is possible to detect using immunological tests. These products are associated with parasite metabolism, are independent of the presence of eggs or proglottids, and are reported to disappear from feces shortly after treatment [30,51]. Coproantigens can also be detected as early as 2 weeks postinfection [52••]. ...
Human neurocysticercosis, caused by the larval
stage of the tapeworm Taenia solium, is an important neurological
disorder reported as a major cause of epilepsy. An
important risk factor for neurocysticercosis is the presence of
human T. solium carriers who, upon open defecation, disseminate
tapeworm eggs, which are infective to both humans and
pigs. In the latter, infection also results in cysticercosis, with
associated health and economic consequences. Control of
T. solium therefore depends greatly on accurate detection
and treatment of carriers. However, the currently available
direct diagnostic tests depend on detection, in feces, of either
parasite stages or parasite antigens and genetic material. The
former are low cost but lack adequate sensitivity and specificity;
the latter are too expensive to be routinely utilized in
endemic communities. Indirect tests based on antibody detection
may only show exposure and not active infection. An
ideal diagnostic test should be one that is low cost and is able
to quickly and reliably detect tapeworm carriers so that appropriate
treatment can be prescribed in order to eliminate the
source of infection. Such a test remains elusive. Efforts
should, therefore, be directed at formulation of a test that is
not only sensitive and specific but also affordable for use in
endemic countries.
... Coproantigen is an inexpensive and useful tool for 'self-detection' of parasitic eggs, but the reported sensitivity is between 0 and 59% [66]. Serum antigen or antibody with ELISA is highly speci c for cysticercosis with little cross-reactivity [67]. The disadvantage is that antibody persists after infection clearance, whereas antigen is only detectable in active cysticercosis [68,69]. ...
... For porcine cysticercosis, tongue inspection is an inexpensive method to quickly recognize T. solium cysts and has a speci city of up to 100% if carried correctly [70]. Porcine serological tests are also available, but similar limitations exist as in humans [67][68][69]. Selection of tests should be contextspeci c considering local laboratory and veterinary infrastructure. If nancially allowed, combining di erent tests can increase reliability of results [12]. ...
Neurocysticercosis (NCC) is a leading cause of preventable epilepsy in lower- and upper- middle-income countries (LMICs/UMICs). NCC is a human-to-human transmitted disease caused by ingestion of Taenia solium eggs from a Taenia carrier. T. solium infection control is the key to reduce NCC incidence. This systematic review aims to identify T. solium control programs that can provide frameworks for endemic areas to prevent NCC-related epilepsy. A systematic search was conducted in PubMed/Medline, Embase, Web of Science, and Cochrane Library databases in March 2021. After title and abstract review, full texts were screened for qualitative analysis. Additional articles were identified via citation search. Of 1322 total results, 34 unique studies were included. Six major intervention types were identified: national policy (8.8%), community sanitation improvement (8.8%), health education (8.8%), mass drug administration (29.4%), pig vaccination and treatment (32.4%), and combined human and pig treatment (11.8%). Overall, 28 (82.4%) studies reported decreased cysticercosis prevalence following the intervention. Only health education and combined human and pig treatment were effective in all selected studies. NCC causes preventable epilepsy in LMICs/UMICs and its incidence can be reduced through T. solium control. Most interventions that disrupt the T. solium transmission cycle are effective. Long-term sustained results require comprehensive programs, ongoing surveillance, and collaborative effort among multisectoral agencies.
... Furthermore, coproantigens are stable in not fixed stool samples stored at room temperature for days, in frozen samples, or in samples prepared with formalin stored at room temperature. They are stable for a long time, i.e. months to years (2). ...
... This serological test provides diagnosis of species-specific circulating antibodies, and there are no cross-reactions with another parasitical infection. This provides an opportunity to conquer some of the troubles that persist with coproantigen examination (2). Specificity of this method was considered to be 100% and sensitivity about 95% (14). ...
Taenia solium is a parasite causing porcine cysticercosis and human taeniosis and cysticercosis, parasitic zoonoses with a serious public health and economic influence. It has been globally ranked as the top foodborne parasite by the Food and Agriculture Organisation of the United Nations (FAO) and the World Health Organisation (WHO). This parasite is transmitted mainly in countryside regions where animals are free roaming, having access to human faeces, and infected pork is widely available. More developed countries eliminated cysticercosis; nonetheless, there are insufficient data about the current endemicity status of T. solium, due to increased human migration from endemic areas. Formally submitted statistics on cysticercosis in pigs are extremely inadequate. This is the result of not reporting all cases of the disease by some countries and lack of molecular verification during identification of the parasite. There is a need to develop diagnostic tests with increased sensitivity and specificity. The purpose of the present review is to summarise current knowledge about diagnostic and control methods concerning T. solium infection. The article does not address the diagnostics of human cysticercosis, since there is a distinct medical field which should be discussed separately. The paper focuses mainly on identifying the sources of T. solium infection, presenting the methods to detect and control porcine cysticercosis and taeniosis in humans.
... Furthermore, coproantigens are stable in not fixed stool samples stored at room temperature for days, in frozen samples, or in samples prepared with formalin stored at room temperature. They are stable for a long time, i.e. months to years (2). ...
... This serological test provides diagnosis of species-specific circulating antibodies, and there are no cross-reactions with another parasitical infection. This provides an opportunity to conquer some of the troubles that persist with coproantigen examination (2). Specificity of this method was considered to be 100% and sensitivity about 95% (14). ...
Taenia solium is a parasite causing porcine cysticercosis and human taeniosis and cysticercosis, parasitic zoonoses with a serious public health and economic influence. It has been globally ranked as the top foodborne parasite by the Food and Agriculture Organisation of the United Nations (FAO) and the World Health Organisation (WHO). This parasite is transmitted mainly in countryside regions where animals are free roaming, having access to human faeces, and infected pork is widely available. More developed countries eliminated cysticercosis; nonetheless, there are insufficient data about the current endemicity status of T. solium , due to increased human migration from endemic areas. Formally submitted statistics on cysticercosis in pigs are extremely inadequate. This is the result of not reporting all cases of the disease by some countries and lack of molecular verification during identification of the parasite. There is a need to develop diagnostic tests with increased sensitivity and specificity. The purpose of the present review is to summarise current knowledge about diagnostic and control methods concerning T. solium infection. The article does not address the diagnostics of human cysticercosis, since there is a distinct medical field which should be discussed separately. The paper focuses mainly on identifying the sources of T. solium infection, presenting the methods to detect and control porcine cysticercosis and taeniosis in humans.
... 24,25 In order to improve the detection of taeniasis cases, a range of immunodiagnostic assays on fecal or sera samples have been developed, resulting in a great improvement in the sensitivity and specificity of diagnostic approches. 26 Copro-Ag diagnostics, based upon the detection of parasite-specific secretory antigens, was first reported in the 1960s; however, it did not gain widespread scientific attention until the 1980s. 26 Copro-Ag detection relies on the presence of specific secretory antigens produced independently from reproductive material and, therefore unlike microscopy, does not depend on the active shedding of eggs or proglottids for infection detection. ...
... 26 Copro-Ag diagnostics, based upon the detection of parasite-specific secretory antigens, was first reported in the 1960s; however, it did not gain widespread scientific attention until the 1980s. 26 Copro-Ag detection relies on the presence of specific secretory antigens produced independently from reproductive material and, therefore unlike microscopy, does not depend on the active shedding of eggs or proglottids for infection detection. Copro-Ag ELISA has now been successfully demonstrated in a variety of situations to detect Taenia spp. ...
Anna L Okello,1 Lian Francesca Thomas2 1Division of Infection and Pathway Medicine, Edinburgh Medical School, Biomedical Sciences College of Medicine and Veterinary Medicine, University of Edinburgh, Scotland; 2Independent Consultant, Lusaka, Zambia Abstract: Human taeniasis is a zoonotic condition resulting from infection with the adult stages of Taenia saginata (“beef tapeworm”), Taenia solium (“pork tapeworm”) or Taenia asiatica (“Asian tapeworm”). Although these parasites have a worldwide distribution, the overwhelming burden is felt by communities in low- and middle-income countries. This is particularly true for T. solium, whereby infection of the central nervous system with the larval stage of the parasite (neurocysticercosis) is a major cause of acquired epilepsy in low-resource settings. With a focus on endemic countries, this review provides an insight into the prevention and management of human taeniasis, concluding with some recent case studies describing their implementation. Discussion of the opportunities and challenges regarding current fecal and serological diagnostic assays for detecting Taenia spp. highlights the importance of accurate and accessible diagnostic options for the field situation. The lack of long-term impact on the parasites’ lifecycle from human anthelmintic treatment, coupled with the propensity for adverse reactions, highlights the importance of a “two-pronged” approach that considers the relevant animal hosts, particularly in the case of T. solium. Aside from the therapeutic options, this review reiterates the importance of adequate assessment and consideration of the associated behavioral and policy aspects around sanitation, hygiene and meat inspection that have been shown to support parasite control, and potential elimination, in endemic regions. Keywords: Taenia solium, Taenia saginata, cysticercosis, zoonotic disease, neglected tropical diseases
... Copro-antigen diagnostics, based upon the detection of parasite specific secretory antigens, was first reported in the 1960's although did not gain widespread scientific attention until the 1980's (Allan et al., 2003). Specific secretory antigens are produced independently from reproductive material and are therefore not reliant on active shedding of eggs or proglottids. ...
... As discussed in Section 1.2.3 on page 11 the copro-antigen ELISA is not species specific (Allan et al., 2003), and in order to determine which species of Taenia was present in the study area the positive samples were tested by the CDC in Washington, USA, using the rEs33 EITB. This assay has high sensitivity and specificity for the detection of T. ...
Taenia solium is a zoonotic helminth which is thought to be one of the leading causes of acquired
epilepsy in the developing world. T. solium cysticercosis infections in pigs and humans and
human taeniasis were diagnosed using antigen-capture ELISAs. The parasite was found to
be endemic in the study site, with cysticercosis being detected by HP10 Ag-ELISA in 6.6%
of human samples (95% C.I. 5.6-7.8%) and 17.2% (95% C.I. 10.2-26.4%) of porcine samples.
Human taeniasis was detected by Copro-Ag ELISA in 19.9% (95% C.I. 18.2-21.8%) of faecal
samples. The study site was found to be co-endemic with a large selection of other neglected
tropical diseases, including soil transmitted helminthiasis, schistosomiasis, strongyloidiasis and
amoebiasis.
Potential control measures for this parasite have been modeled and the exclusion of infective
pork from the food chain through the use of a pre-slaughter test for pig farmers, traders and
slaughtermen was found to have the potential to avoid 72.6% (95% C.I. 62.1-80.9%) of infective
meals consumed in the area at an incremental cost-effectiveness ratio (ICER) of $0.25 (0.2-0.35).
Such a diagnostic tool is currently under development and its performance was evaluated as
part of this thesis. The novel, user-friendly lateral flow assay, utilising the HP10 monoclonal
antibody, was evaluated using a Bayesian framework and was estimated to perform with a
Sensitivity of 82.7% (95% B.C.I. 72.5-91.9%) and Specificity of 87% (95% B.C.I. 80.2-93.4),
results which demonstrate the potential utility of this test in epidemiological studies and in
control strategies.
Free-ranging pig production has been previously demonstrated to be a key risk factor for porcine
cysticercosis and is commonly practised in this study region. A study carried out as part of
this thesis found that these pigs have a home range of 15,085m2 which is almost 10 times the
average area of a homested. This work indicates that pigs can be exposed to infective eggs
from any human T. solium carriers within that homerange area, greatly assisting transmission
of this parasite. Western Kenya is a severely deprived region where pig production is becoming
hugely popular and is seen as a major tool for economic development, yet the data presented in
this thesis indicates an area with endemic status for the harmful parasite T. solium, for which
effective control strategies are desperately required.
... The detection of human cysticercosis is one of the keys to the management of the disease [28]. Identification of T. solium proglottids or eggs, which have both low sensitivity and specificity, in human faeces is confirmatory of infection by the adult stage of the parasite [28]. ...
... The detection of human cysticercosis is one of the keys to the management of the disease [28]. Identification of T. solium proglottids or eggs, which have both low sensitivity and specificity, in human faeces is confirmatory of infection by the adult stage of the parasite [28]. Deoxyribonucleic acid (DNA) based technologies are sensitive and specific [29], but their use is not common. ...
... Por otra parte, la observación microscópica de huevos, mediante exámen directo o método de Graham, sólo puede indicar teniasis, pero no sirve para determinar si la enfermedad está producida por T. solium o T. saginata, dado que morfológicamente los huevos son indistinguibles. Estos métodos Parasitologyógicos se caracterizan por exhibir baja sensibilidad (Allan et al., 2003). ...
... Ultimamente, se han identificado por proteomica 2 antígenos de el adulto de T. solium, TSES33 y TSES38, que fueron reconocidos por sueros de teniasicos y no por aquellos de pacientes con cisticercosis, demostrando que son estadio-específicos (Levine et al., 2004). A pesar de estos avances hay que tener en cuenta que la detección de anticuerpos en teniasis tiene como desventaja que después del tratamiento los anticuerpos permanecen y podrían rendir falsos positivos (Allan et al., 2003). ...
... As the study was epidemiological surveillance of echinococcosis in sheep population and correlate with the dog menace it was necessary to know the status of parasite in dog population roaming/in contact with the sheep population thus matter of public health significance. As the dogs are definitive host of this parasite and necropsy is considered as the gold standard for diagnosis but to keep the animal welfare matter into consideration alternatives have to be checked for diagnosis of Echinococcosis in natural harbours [2]. ...
Echinococcosis a zoonotic disease caused by the tapeworm transmitted by the definitive host dogs and wild carnivores to the domestic animals (intermediate hots) and humans (aberrant intermediate hosts) either directly or indirectly shed from faeces. Two foremost diagnostic methods broadly used in dogs are purgation with arecoline compounds and necropsy of the small intestine. Alternatively, immunodiagnostic techniques are being used to detect specific antibodies or antigens. In the present study 100 dogs revealed an overall 8 %taeniid eggs, the prevalence of taeniid eggs was much higher in stray dogs (14%) having access to condemned meat/offal living in an around slaughter houses as compared to pet dogs (2%). The overall prevalence of echinococcosis using latex agglutination test as a diagnostic tool in 100 suspected serum samples of dogs screened was found to be 10 per cent with highest prevalence of 18 per cent in stray dogs and least 2 per cent in pet dogs. A total of 90 suspected serum samples were screened for the detection of Echinococcus granulosus antibodies using anti-dog echinococcus antibody (IgG) direct ELISA kit, of which only 13 samples were found positive with a prevalence of 14.44 per cent. Highest prevalence of 26.66 per cent was observed in stray dogs and the lowest 2.22 per cent in pet dogs. Establishing epidemiological figures of echinococcosis and preventing human and livestock infection and also, performing a rapid and on-site diagnosis/screening for infection in definitive hosts would be advantageous, a goal behind this study.
... This has also been recorded in previous studies [3,9,24,[35][36][37][38][39]. In addition, it has been reported that no single taeniosis diagnostic technique will "always" detect infection [37,40,41]. Nevertheless, discordance among reference tests in our study was striking since none of the samples was positive for all the reference tests. ...
Taenia solium taeniosis diagnosis is challenging because current tests perform sub-optimally and/or are expensive, require sophisticated equipment, infrastructure and trained manpower, and therefore are not community deployable. A recently-developed, multi-strip, T. solium point-of-care test (TS POC) for simultaneous detection of tapeworm (TS POC T) and cysticercus (TS POC CC) human antibodies was evaluated for diagnostic accuracy on consecutively recruited community participants in Sinda district, Zambia. All participants were tested using the TS POC test. All test-positives and 20% of the test-negative participants were invited to give a blood and stool sample for reference testing. Three different reference tests were used for taeniosis diagnosis: recombinant rES33 enzyme-linked immunoelectrotransfer blot (rES33 EITB), copro PCR and copro Ag ELISA. Bayesian analysis with probabilistic constraints was used to estimate sensitivity and specificity. In total, 1254 participants were tested with the TS POC test, of whom 13 tested positive using the TS POC T. Based on 161 participants with complete data, the estimated sensitivity and specificity for the TS POC T test were 38% (95% CI: 5–93%) and 99% (95% CI: 98–100%), respectively. The challenge of highly variable inter-assay performance is highlighted. We recommend either increasing the sensitivity or redesigning the test.
... Although global eradication of T. solium transmission is unlikely in the short-term, local control or elimination is now possible [3,4] due to the availability of new tools that can be deployed to interrupt transmission. These include effective treatment of taeniasis [5,6] and porcine cysticercosis [7,8], improved diagnostic tests [9,10], and a vaccine to prevent pig infection [11,12]. In 2012, shortly after the success of a large-scale elimination demonstration in Peru that effectively implemented many of these tools [3], the World Health Organization (WHO) declared ambitious targets for global control and elimination of T. solium. ...
Background
The pork tapeworm ( Taenia solium) is a parasitic helminth that imposes a major health and economic burden on poor rural populations around the world. As recognized by the World Health Organization, a key barrier for achieving control of T . solium is the lack of an accurate and validated simulation model with which to study transmission and evaluate available control and elimination strategies. CystiAgent is a spatially-explicit agent based model for T . solium that is unique among T . solium models in its ability to represent key spatial and environmental features of transmission and simulate spatially targeted interventions, such as ring strategy.
Methods/Principal findings
We validated CystiAgent against results from the Ring Strategy Trial (RST)–a large cluster-randomized trial conducted in northern Peru that evaluated six unique interventions for T . solium control in 23 villages. For the validation, each intervention strategy was replicated in CystiAgent, and the simulated prevalences of human taeniasis, porcine cysticercosis, and porcine seroincidence were compared against prevalence estimates from the trial. Results showed that CystiAgent produced declines in transmission in response to each of the six intervention strategies, but overestimated the effect of interventions in the majority of villages; simulated prevalences for human taenasis and porcine cysticercosis at the end of the trial were a median of 0.53 and 5.0 percentages points less than prevalence observed at the end of the trial, respectively.
Conclusions/Significance
The validation of CystiAgent represented an important step towards developing an accurate and reliable T . solium transmission model that can be deployed to fill critical gaps in our understanding of T . solium transmission and control. To improve model accuracy, future versions would benefit from improved data on pig immunity and resistance, field effectiveness of anti-helminthic treatment, and factors driving spatial clustering of T . solium infections including dispersion and contact with T . solium eggs in the environment.
... Eggs are released into the environment via the faeces freely or within the detached gravid proglottids by apolysis, approximately 2-3 times per week Pawlowski, 2002), with each adult worm capable of shedding up to 300,000 eggs per day (Pawlowski, 2002). Specific tapeworm proteins of interest are the copro-antigens, which are genus-specific parasite products associated with metabolism, and are found in the faeces of infected hosts independent of the presence of eggs and proglottids (Allan et al., 2003;Mwape and Gabriël, 2014). These antigens (Ag) form the target for the widely used enzyme-linked immunosorbent assay (copro-Ag-ELISA) (Allan et al., 1990), specifically the assay developed from hyperimmunized rabbit-derived polyclonal antibodies with either adult worm excretionsecretion (ES) or somatic products (Allan et al., 1990(Allan et al., , 1992Deplazes et al., 1991;Mwape and Gabriël, 2014). ...
Infection with the pork tapeworm (Taenia solium) is responsible for a substantial global burden of disease, not only restricted to its impact on human health, but also resulting in a considerable economic burden to smallholder pig farmers due to pig cysticercosis infection. The life-cycle, parasitology and immunology of T. solium are complex, involving pigs (the intermediate host, harbouring the larval metacestode stage), humans (the definitive host, harbouring the adult tapeworm, in addition to acting as accidental intermediate hosts) and the environment (the source of infection with eggs/proglottids). We review the parasitology, immunology, and epidemiology of the infection associated with each of the T. solium life-cycle stages, including the pre-adult/adult tapeworm responsible for human taeniasis; post-oncosphere and cysticercus associated with porcine and human cysticercosis, and the biological characteristics of eggs in the environment. We discuss the burden associated, in endemic settings, with neurocysticercosis (NCC) in humans, and the broader cross-sectoral economic impact associated both with NCC and porcine cysticercosis, the latter impacting food-value chains. Existing tools for diagnostics and control interventions that target different stages of the T. solium transmission cycle are reviewed and their limitations discussed. Currently, no national T. solium control programmes have been established in endemic areas, with further work required to identify optimal strategies according to epidemiological setting. There is increasing evidence suggesting that cross-sectoral interventions which target the parasite in both the human and pig host provide the most effective approaches for achieving control and ultimately elimination. We discuss future avenues for research on T. solium to support the attainment of the goals proposed in the revised World Health Organisation neglected tropical diseases roadmap for 2021–2030 adopted at the 73rd World Health Assembly in November 2020.
... At the beginning of 1990's, an enzyme-linked immunoassay (ELISA) was developed to detect coproantigens, it has high sensitivity and does not cross react with other helminths with the exception of T. saginata (Allan et al., 1990;Flisser et al., 2005). Other stool-based diagnosis include antigen based an electro-immuno-transfer-blot (EITB) (Allan et al., 2003;Deckers and Dorny, 2010) and amplification of DNA using polymerase chain reaction using specific primers (Carabin et al., 2017). However, none are commercially available, and more sensitive methods are difficult to implement in endemic areas. ...
Zoonotic taeniasis caused by the adult stage of Taenia solium, Taenia saginata or Taenia asiatica are considered neglected tropical diseases by the World Health Organization. The life cycle of these 3 metazoan species is very similar and includes an intermediate host: pigs in the case of T. solium and T. asiatica, and cattle in the case of T. saginata. By eating meat (pork/T. solium, T. asiatica; beef/T. saginata) containing live cysticerci, humans develop taeniasis, which is practically asymptomatic but is the main risk factor for intermediate hosts to become infected. T. saginata causes bovine cysticercosis, while T. solium and T. asiatica cause swine cysticercosis, of veterinary and economic importance. T. solium cysticerci cause neurological disease in humans: neurocysticercosis. Cysticerci develop after ingesting microscopic eggs released from a human tapeworm carrier. Here we describe the life stages of the parasites, diagnosis, pathogenesis, symptomatology of neurocysticercosis, and prevention and control measures. Highlighting the need to validate diagnostic tools, treatments and vaccination in endemic areas, with the challenge of addressing the most vulnerable populations that lack resources. If people understand the transmission route, avoid eating uncooked or insufficiently cooked meat and have adequate hygienic habits, the life cycle of the 3 zoonotic Taenia species may be interrupted. In addition, we describe the growing field of immune response and immunomodulation elicited by the parasites, which may provide essential tools for diagnosis, treatment, control of taeniasis/cysticercosis, as well as for identification of parasite-derived immunomodulators that could aid in the treatment of emerging inflammatory diseases worldwide.
... While pigs can be infected with both T. hydatigena and T. solium, the Ag ELISA does not differentiate between the two species [27]. low sensitivity and specificity though it is regarded as confirmatory of infection by the adult stage of the parasite [28]. Deoxyribonucleic acid (DNA) based technologies are sensitive and specific [29], but their use is not common. ...
... and poses high risk of infection (Allan and Craig, 2006;Mwape and Gabriël, 2014). Improved techniques such as copro-antigen enzyme-linked immunosorbent assay (ELISA), native and recombinant antigen based enzyme-linked immuno electro transfer blot (EITB) techniques are available but not commercialized for routine use (Allan et al., 2003;Deckers and Dorny, 2010). Real time polymerase chain reaction for taeniosis diagnosis has also been developed (Carabin et al., 2017). ...
Background:
Foodborne Neglected Zoonotic Helminths (FNZH) are parasites of both economic and public health importance. They include Taenia solium, Echinococcus granulosus sensu lato, Echinococcus multilocularis and Foodborne trematodes (FBT). FNZH are earmarked for major interventions for control, elimination and eradication. This systematic review highlights the progress towards development of rapid tests for the diagnosis of FNZH since 2010 when they were listed as neglected tropical diseases.
Methodology:
A systematic search was conducted in three databases, World of Science, Embase and PubMed using the same search phrase. The search produced 480 hits. Three studies from back referencing were included. Only 22 of these met the inclusion criteria. Data was extracted from these and presented qualitatively.
Results:
Twenty-five rapid diagnostic tests were found to have been developed since 2010, eight for diagnosis of T. solium infections, eight for echinococcosis and nine for FBT infections. The rapid tests for diagnosing T. solium infections included six antibody detecting and two antigen detecting tests. They constitute a combination among them, with some tests providing qualitative, others quantitative results. Similarly, seven out of the eight rapid tests developed for Echinococcus infections were antibody detecting tests save for one loop mediated isothermal amplification test. All of them were qualitative tests. For FBT infections, nine rapid tests were described; two antibody and one nucleic acid detecting test for diagnosis of Fascioliasis; three nucleic acid detecting tests for Opisthorchiasis; one antibody detecting test for Paragonimiasis; and for Clonorchiasis, one antibody and one nucleic acid detecting test. The FBT infection rapid tests were all qualitative in nature. Most of these tests have not undergone field evaluation in endemic areas where they will be used most.
Conclusion:
This review describes the development and evaluation of rapid diagnostic tests, while highlighting the need for in depth validations of the tools to determine how well they can perform in endemic areas.
... The identification of adult T. solium carrier status in NCC cases is currently often neglected largely due to a poor yield of stool examinations for Taenia eggs and the technical difficulties in testing (Allan et al, 2003). Demonstration of Taenia eggs in stool samples provides the most definitive diagnosis but is unreliable due to the intermittent nature of egg excretion. ...
Neurocysticercosis, or brain infestation with the larval stage of Taenia solium, is the most common risk factor for epilepsy in many endemic regions of the world. Hardly any cases are seen in Western developed countries, including Britain. However, a sizeable number (n = 450) was seen among British soldiers returning from deputation to India, then a British colony, first reported by Col. MacArthur at the Queen Alexandria Military Hospital in 1931. Here, we review the influence of the perceptive observations of British Army medics on the understanding of the parasitic disorder. The majority of these people presented with epilepsy. Among the contributions of the army medics were establishing the diagnosis, initially by histological examination of subcutaneous and muscular infestation, and later by radiography, clarifying the prognosis and the role of medical and surgical treatments and uncovering the close relationship between the larval (cysticercosis) and adult (intestinal tapeworm) stages of T. solium.
... A case definition of ODR ³ 40% was chosen with the goal of reducing false positives due to nonspecific binding and cross-reaction with other Taenia spp., which may occur at lower ODR values. 19,20 After each round of mass treatment and screening, positively identified cases were followed up with multiple rounds of niclosamide therapy and stool screening until parasite clearance was confirmed. ...
The pork tapeworm, Taenia solium, is among the leading causes of preventable epilepsy in the world and is common in rural areas of developing countries where sanitation is limited and pigs have access to human feces. Prior studies in rural villages of Peru have observed clusters of T. solium cysticercosis among pigs that live near human tapeworm carriers. Such spatial analyses, however, have been limited by incomplete participation and substandard diagnostic tests. In this study, we evaluated the association between necropsy-confirmed cysticercosis in pigs and their distance to T. solium tapeworm carriers in six villages in northern Peru. A total of six (1.4%) tapeworm carriers were detected using copro-antigen enzyme-linked immunosorbent assay and seven of 10 (70%) pigs belonging to the tapeworm carriers were found with viable cyst infection on necropsy. This was significantly greater than the prevalence of viable cyst infection among pigs living < 500 m (11%) and > 500 m (0.5%) from a tapeworm carrier (P < 0.001 for distance trend). Similar statistically significant prevalence gradients were observed after adjustment for possible confounders and for other pig-level outcomes including infection with > 10 viable cysts, degenerated cyst infection, and serological outcomes. This investigation confirms that porcine cysticercosis clusters strongly around tapeworm carriers in endemic rural regions of northern Peru and supports interventions that target these hotspots.
... Copro Ags are detectable in the feces of an infected host irrespective of the developmental stage of the adult tapeworm or the presence of eggs or proglottids in the sample (Allan et al., 1990). Copro Ags are stable at room temperature for days in unfixed fecal samples and for months in frozen or formalin-fixed samples (Allan et al., 1990;Allan et al., 2003;Murrell et al., 2005). Some copro Ag enzyme-linked immunosorbent assays (ELISAs) have achieved over 99% specificity in field studies (Allan et al., 1996) but most cannot differentiate between T. solium and T. saginata infections which can be problematic in co-endemic areas (Allan et al., 1990;Allan et al., 1996;Deckers and Dorny, 2010). ...
https://biblio.ugent.be/publication/8582700
... An immunoblot assay was developed to diagnose T. solium taeniosis using excretory/secretory antigens collected from in vitro cultured T. solium tapeworms. Although this particular test does not cross-react with T. saginata infection, development of a similar assay for T. saginata might lead to a new diagnostic technique (Wilkins et al., 1999;Allan et al., 2003). ...
... Overall, however, the test was the best laboratorybased test for ante mortem diagnosis of canine echinococcosis . Parasite coproantigens have been defined as parasite specific products in the faeces of the host that are amenable to immunological detection and are associated with the parasite metabolism (Allan et al., 2003). ...
Echinococcus granulosus is a tiny tapeworm that parasitizes the small intestine of canids, mainly dogs,
which act as definitive hosts for the parasite. Infected dogs are the main source of infection to humans
and livestock which act as intermediate hosts resulting in hydatid disease condition. E. granulosus is
widely distributed in many parts of the world, and is very common in North African countries. In Libya,
the rate of infection with echinococcosis in dogs was reported to be lower than 7 to 80% in stray dogs,
34.8 to 60% in sheep/guard dogs and 7.7 to 21.6% in farm/house dogs. This data fulfills the world health
organization (WHO) criteria and suggests that the incidence of infection with echinococcosis/
hydatidosis in some parts of the country can be reaching the level of hyper endemic. Diagnosis of
echinococcosis in infected dogs can be performed by isolating the parasite from their faeces or from
the contents of their small intestine after necropsy. Recent developments in immunodiagnostic assays
for echinococcosis in dogs have been described. Public health and risk factors as well as ways of
hydatid disease treatment and various control strategies, including the use of veterinary vaccines, have
also been discussed.
... Since the eggs of the various Taenia spp. cannot be distinguished microscopically from one another or from those of Echinococcus spp., other diagnostic procedures should be employed (Allan et al. 2003). There is a need to develop a diagnostic method that would detect Taenia infections in dogs at species level. ...
The prevalence of taeniasis was determined during the period January to April 2013 in a cross-sectional study of non-descript domestic dogs from the livestock–wildlife ecosystem of Ngorongoro, Tanzania. Taeniid eggs were determined by screening faecal samples using the formalin-ether sedimentation technique. Predisposing factors for dog infection were assessed in relation to demographic, husbandry and management data. Of the 205 faecal samples screened, 150 (73.2%) were positive for taeniid eggs. The prevalence of dogs harbouring taeniid eggs was 80%, 30.2% and 75.3% in the less than 1 year, 1–3 years and greater than 3 years of age groups, respectively. Age group and sex prevalence in dogs did not differ significantly (P > 0.05), although the females showed a marginally higher prevalence (73.8%) in comparison to the males (72.7%). Taeniid eggs were significantly more likely to be found in the faeces of dogs located in Waso (80.6%) and Endulen (75%) than in Malambo (63.2%, P < 0.05). The study revealed that dogs owned and raised by agro-pastoralists were at a lower risk of acquiring Taenia spp. infection (P = 0.001) than those that were raised by pastoralists. The majority of dog owners were not aware of the predisposing factors and the mode of transmission of taeniids. Dogs were frequently fed on viscera, trimmings and the heads of slaughtered animals, and they were not treated for parasitic infections. The findings of this study indicate that taeniasis is prevalent among non-descript dogs in Ngorongoro, underscoring the need for further research and active surveillance to better understand the transmission cycle of Taenia spp. in a wider geographical area in Tanzania.
... However, these high proportion of positive humans and pigs must be cautiously interpreted. Indeed, the copro-Ag ELISA is only genus specific and as such cannot differentiate between T. solium and Taenia saginata infections (Allan et al., 2003), while Ag-ELISA cannot distinguish T. solium from Taenia hydatigena infections in pig (Dorny et al., 2004a). It is therefore probable that the proportions of positive human and pigs could be overestimated. ...
Background:
Taenia solium infections are mostly endemic in less developed countries where poor hygiene conditions and free-range pig management favor their transmission. Knowledge on patterns of infections in both human and pig is crucial to design effective control strategies. The aim of this study was to assess the prevalence, risk factors and spatial distribution of taeniasis in a rural area of the Democratic Republic of Congo (DRC), in the prospect of upcoming control activities.
Methods:
A cross-sectional study was conducted in 24 villages of the health zone of Kimpese, Bas Congo Province. Individual and household characteristics, including geographical coordinates were recorded. Stool samples were collected from willing participants and analyzed using the copro-antigen enzyme-linked immunosorbent assay (copro-Ag ELISA) for the detection of taeniasis. Blood samples were collected from pigs and analyzed using the B158/B60 monoclonal antibody-based antigen ELISA (sero-Ag ELISA) to detect porcine cysticercosis. Logistic regression and multilevel analysis were applied to identify risk factors. Global clustering and spatial correlation of taeniasis and porcine cysticercosis were assessed using K functions. Local clusters of both infections were identified using the Kulldorff's scan statistic.
Results:
A total of 4,751 participants above 5 years of age (median: 23 years; IQR: 11-41) were included. The overall proportion of taeniasis positivity was 23.4% (95% CI: 22.2-24.6), ranging from 1 to 60% between villages, with a significant between-household variance of 2.43 (SE=0.29, p<0.05). Taeniasis was significantly associated with age (p<0.05) and the highest positivity was found in the 5-10 years age group (27.0% (95% CI: 24.4-29.7)). Overall, 45.6% (95% CI: 40.2-51) of sampled pigs were sero-positive. The K functions revealed a significant overall clustering of human and pig infections but no spatial dependence between them. Two significant clusters of taeniasis (p<0.001; n=276 and n=9) and one cluster of porcine cysticercosis (p<0.001; n=24) were found.
Conclusion:
This study confirms high endemicity and geographical dispersal of taeniasis in the study area. The role of age in taeniasis patterns and significant spatial clusters of both taeniasis and porcine cysticercosis were evidenced, though no spatial correlation was found between human and pig infections. Urgent control activities are needed for this endemic area.
... Procedimiento de elisa-coproantígeno: Se siguió el método descrito por (Allan et al., 2003) con modificaciones adaptadas en el laboratorio de inmunología de la Universidad Cayetano Heredia. Las muestras de heces fueron centrifugadas ( Centrifuga Thermo Scientific Sorvall Newtown CT) a 3200g por 10 minutos para obtener el sobrenadante, se preparó una dilución de 1:4000 del anticuerpo primario (RbATSIgG-8) con buffer (pH 8) en cada pozo de la microplaca (Inmunolon 4 -Dynex) se agregó 100µl y se incubó (Incubadora Thermo Scientific Sorvall Newtown CT) a 4°C por 24 horas, inmediatamente se lavó 3 veces con 200µl de buffer fosfato salino Tween 20 al 0,1% (C58 H114 O26 polyoxyethylene 20 sorbitan monolaurate pH 7.3 Sigma), se añadió 100 µl de buffer fosfato salino Tween 20 al 0,3% (pH 9,6-Sigma), se dejó 1 hora a temperatura ambiente, el sobrenadante fue eliminado y se agregó 50µl de suero fetal bovino (HIFBS; Gibco) y 50µl de muestras de heces del sobrenadante incubando por 1 hora, después se lavó tres veces con 100µl de PBS Tween 20 al 0,1%, se adicionó 100µl de conjugado de peroxidasa anti-T. ...
p align="center"> RESUMEN
La teniasis, es una enfermedad parasitaria endémica distribuida a nivel mundial, la detección de antígenos por coproantígeno tiene mejor sensibilidad diagnóstica. Los objetivos del estudio fueron: Determinar la prevalencia de Taenia sp en dos poblaciones rurales utilizando la técnica de microscopia y elisa-coproantigeno; Comparar la sensibilidad de elisa-coproantigeno con el análisis microscópico. Se analizaron 723 muestras de heces. Los resultados en: Copamaya por microscopia 1,7% (3/173) de positivos, mediante elisa-coproantigeno 2,8% (5/173). En Pharata por microscopia 2,2% (12/550), por elisa-coproantigeno 3,3% (18/550). En ambas localidades las edades de 30-59 obtuvieron mayor prevalencia. La prueba de elisa- coproantigeno detectó mayor número de casos en comparación con la microscopia. 12 muestras positivas por elisa-coproantigeno y microscopia se confirmó al observar el parasito en el tratamiento. En 7 muestras elisa-coproantigeno positivo y microscopia negativo no se pudo confirmar la presencia de taenia por que no se administró tratamiento por el bajo valor de porcentaje de positividad entre 16,28 a 31,28. Conclusión: La prevalencia de Taenia sp en Copamaya por microscopia es 1,7%; en Pharata 2,2%; por elisa-coproantigeno 2,8% y 3,3% respectivamente. La prueba de elisa-coproantigeno detectó mayor número de casos positivos frente al análisis microscópico, pero en algunos casos son complementarios para el diagnóstico de la teniasis. Mediante la prueba de t student para analizar las diferencias significativas de los dos métodos de diagnóstico se obtuvo (P=0.665).
DIAGNOSIS OF HUMAN TAENIASIS BY COPROANTIGEN ELISA AND TRADITIONAL MICROSCOPY IN THE RURAL POPULATIONS OF PUNO -PERU
ABSTRACT
The tapeworm is a parasitic disease endemic in developing worldwide distributed, the antigen detection by coproantigen-Elisa has better diagnostic sensitivity. The objectives studies were: To determine the prevalence of Taenia sp in two rural populations using the technique of microscopy and coproantigen- Elisa; to compare the sensitivity of coproantigen-elisa with microscopic analysis. 723 stool samples were analyzed. The results show: In Copamaya it was possitive by microscopy 1, 7% (3/173), by coproantigen-elisa 2, 8% (5/173), while in Pharata by microscopy 2, 2% (12/550) and 3.3% (18/550) by coproantigen-elisa. In both locations the ages of 30- 59 had the greatest number of positive. Elisa-coproantigen test detected more cases compared with microscopy. 12 positive samples were confirmed by microscopy and coproantigen it is confirmed by the parasite in the treatment. In 7 samples coproantigen-elisa positive and negative microscopy could not confirm the presence of taenia because treatment is not administered by the low value of percentage of positivity between 16, 28 to 31,28. Conclusions: the prevalence of Taenia sp in population the Copamaya by microscopy is 1.7% and Pharata 2.2%, by coproantigen-elisa 2.8% and 3.3% respectively. The test coproantigen-elisa detected highest number of positive cases compared to microscopic analysis, but in some cases is complementary to diagnose tapeworm. Using the student t test to analyze the significant differences in the two diagnostic methods was obtained (P = 0.665).</p
... Copro-antigen diagnostics, based upon the detection of parasite specific secretory antigens, was first reported in the 1960's although did not gain widespread scientific attention until the 1980's (Allan et al., 2003). Specific secretory antigens are produced independently from reproductive material and are therefore not reliant on active shedding of eggs or proglottids. ...
Landscape Analysis commissioned by the WHO for the Informal Consultation: Assembling a framework for intensified control of taeniasis and neurocysticercosis caused by Taenia solium. Geneva, 17th& 18th July 2014
... No obstante, su sensibilidad y especificidad son bajas (Salvatella & Eirale, 1996, Meza & Aguilar, 2002 y no permiten diferenciar entre las especies de Taenia. Técnicas actuales como las pruebas inmunológicas (Allan et al.,1992;Wilkis et al., 1999;Allan et al., 2003) y las moleculares (Nunes et al., 2006;Rodríguez-Hidalgo et al., 2007) han permitido identificar la gravedad del problema en el hombre. La variación genética dentro de la especie de T. solium es aún desconocida aunque algunos autores ya han encontrado diferencias de acuerdo a su ubicación geografía (González et al., 2000;Ito et al., 2003;Campbell et al., 2006;Maravilla et al., 2008). ...
Resumen L a teniasis e himenolepiasis son consideradas endé-micas en el Ecuador. Estas zoonosis son causadas por las formas adultas de cestodos del género Tae-nia e Hymenolepis. La infestación por Taenia spp. es una zoonosis cuyas tasas de prevalencia varían en función de diversos factores socio-económicos y culturales. El comportamiento humano,
... Integration of T. solium control with existing MDA programmes for STHs or other parasitic NTDcausing organisms such as foodborne trematodes or those causing schistosomiasis offers the opportunity to capitalize on existing frameworks for control under larger NTD programmes. Diagnosis of the presence of adult tapeworms relies on the detection of parasite antigens in faeces (coproantigens), and tests have good specificity and sensitivity [65]. There have been advances in the diagnosis of T. solium infections with immunodiagnostics [21]; serological tests indicate whether the cysts carried in people or animals are alive or dead (treatment is appropriate for live cysts). ...
The Neglected Zoonotic Diseases have been all but eradicated in wealthier countries but remain major causes of ill-health and mortality across Africa, Asia and Latin America. This neglect is, in part, a consequence of under-reporting, resulting in underestimation of their global burden that in turn, downgrades their relevance to policy makers and funding agencies. Increasing awareness about the causes of NZDs and how they can be prevented could reduce the incidence of many endemic zoonoses. Addressing the NZDs by targeting the animal reservoir can deliver a double benefit, as enhanced animal health means a reduced risk of infection for humans, as well as improved livelihoods through increased animal productivity. Advocacy for NZD control is increasing, but with it comes a growing awareness that NZD control demands activities both at scale and over a long period of time. Despite the promise of cheap, effective vaccines or other control tools, these endemic diseases will not be sustainably controlled in the near future without long term financial commitment, particularly as disease incidence decreases and other health priorities take hold. NZD intervention costs can seem high when compared to the public health benefits alone, but these costs are easily outweighed when a full cross sector analysis is carried out and monetary/non-monetary benefits - particularly regarding the livestock sector - are taken into account. Public-private partnerships have generated advocacy for human disease control and could prove equally effective in addressing endemic zoonoses through harnessing social impact investments. Evidence of the disease burdens imposed on communities by the neglected zoonoses and demonstration of the cost effectiveness of integrated control can strengthen the case for a One Health approach towards endemic zoonotic disease control.
Copyright © 2015. Published by Elsevier Ltd.
... Le diagnostic est difficile en raison de la faible sensibilité de l'examen parasitologique des selles et par la difficulté de différencier au microscope les oeufs de T. solium de ceux de T. saginata. La détection de coproantigènes par ELISA est seulement spécifique du genre Taenia [11], mais leur présence est indépendante de la charge parasitaire et ils disparaissent en quelques jours après traitement [12]. Aujourd'hui, des techniques de détection d'acide désoxyribonucléique ont été décrites, qui permettent de distinguer les différentes espèces du genre Taenia [13]. ...
Within the genus Taenia, three species are human parasites: T. solium, T. saginata and a new uncommon species, T. asiatica, described recently in Asia. T. saginata and T. solium live as adult tapeworms in human intestines, where they cause taeniasis. T. saginata is widely present worldwide, in all regions where cattle are bred. T. solium is endemic in many countries where livestock and consumption of pigs are common. Cattle and pigs become infected by ingesting eggs emitted by humans into the environment and serve as the respective intermediate hosts of these helminths and host larval forms, or metacestodes or cysticerci. Cysticerci develop into adult worms in the human intestines after a person has eaten contaminated raw or undercooked meat. In the T. solium, eggs are also human contaminants. Humans, like swine, can develop cysticercosis after ingesting eggs with water or contaminated food, or via dirty hands. The clinical manifestations of cysticercosis are highly variable both in kind and in severity. The period between initial infection and the onset of symptoms can also vary. The clinical expression of cysticercosis is generally dependent on the number, size and location of the cysts, as well as the host immune response to the parasite. The preferred locations are the muscles, subcutaneous tissues, central nervous system (CNS), and eyes. Subcutaneous and muscular forms are often asymptomatic. Severe cysticercosis is due to larvae located in human CNS - neurocysticercosis. The World Health Organization (WHO) lists neurocysticercosis as a neglected tropical disease. It estimates that about 50 million people worldwide have neurocysticercosis in the world and that it causes about 50,000 deaths each year. Its most frequent clinical manifestations are seizures, intracranial hypertension, neurological deficits, and sometimes psychiatric manifestations. It is also responsible for more than 50% of the cases of late-onset epilepsy in developing countries. The T. solium taeniasis/cysticercosis complex is endemic in many developing countries in sub-Saharan Africa, Latin America, and Asia. Although T. solium had virtually disappeared in developed countries due to industrialization, improved methods of husbandry, and health checks, cysticercosis and neurocysticercosis are diagnosed anew in North America, Europe and Australia due to increased immigration from endemic areas. Cysticercosis is considered an eradicable disease. Although theoretically feasible, this concept has been replaced by projects to control and reduce the impact of cysticercosis on human health (through mass treatment of people, veterinary control of pigs, improved farming techniques, and health education).
... sensibilidad, debido a la expulsión irregular de las proglótides (9). ...
... 26,27 Serologic methods, which are available only in research settings, may be used to identify T. solium tapeworm carriers; however, because antibody persists for an unknown period after treatment, serologic testing may produce false-positive results if a patient has been treated for taeniasis in the recent past. 28 Management. The treatment of neurocysticercosis is complex and readers are referred elsewhere for more complete discussion of its intricacies. ...
Cysticercosis is a potentially fatal and preventable neglected parasitic infection caused by the larval form of Taenia solium. Patients with symptomatic disease usually have signs and symptoms of neurocysticercosis, which commonly manifest as seizures or increased intracranial pressure. Although there are many persons living in the United States who emigrated from highly disease-endemic countries and there are foci of autochthonous transmission of the parasite in the United States, little is known about burden and epidemiology of the disease in this country. In addition, despite advances in the diagnosis and management of neurocysticercosis, there remain many unanswered questions. Improving our understanding and management of neurocysticercosis in the United States will require improved surveillance or focused prospective studies in appropriate areas and allocation of resources towards answering some of the key questions discussed in this report.
In Guatemala, neurocysticercosis (NCC) was first recognized in 1940; since then, cases of NCC have been reported in all Guatemalan departments. However, epidemiological studies on Taenia solium infections are scarce and most information remains unpublished. This study aims to provide evidence of T. solium infections as a public health problem in Guatemala. All information available, either published or unpublished, on T. solium infections in the country was compiled. Official data from the Ministry of Health for the period 2002-2019 were reviewed and analyzed, and all cases of T. solium infections were classified and counted. In total, 5246 cases of taeniasis and 454 cases of human cysticercosis were recorded. On the other hand, 44 studies were identified, mostly from local journals, which included 1591 cases of taeniasis, 543 cases of human cysticercosis, and 2590 cases of porcine cysticercosis. Cases were classified by geographic region, patient sex, and Taenia species in taeniasis cases when information was available, and the departments with the highest number of taeniasis and cysticercosis cases were identified. Meanwhile, in Zacapa, a northeastern department of Guatemala with one the highest number of taeniasis cases, a young man diagnosed with a severe form of NCC and two cases of porcine cysticercosis (both confirmed by necropsy) were identified. Taken together, the data herein reported indicate that T. solium infections are a major health problem in Guatemala that needs to be addressed.
Taenia solium (T. solium) infections are of public health concern in most developing countries where diagnosis of the diseases is still a major challenge. This is due to the high cost and technique nature of most of the reliable diagnostic tools that are commercially available. In this study, serological tests developed from crude cyst antigens (Ags) of T. solium, were established at the University of Zambia, and evaluated for their sensitivity and specificity in detecting circulating cysticerci serum antibodies (Abs) in human. The crude antigen was produced from cysts of T. solium collected from pigs from rural Zambia. The antibodies –Enzyme-linked immunosorbent assay (Ab-ELISA) and Electroimmunotransfer blot (EITB) tests were evaluated using a commercial (QualiCode™ Cysticercosis Kit) Immunoblot, in order to estimate their sensitivity and specificity. The Ab-ELISA used a cut off-point of 15 antigen concentration of dilute serum. The Ab-ELISA showed a sensitivity and specificity of 16.67% and 91.94%, respectively. The crude antigen EITB used the 8-10 kDa antigenic bands to detect T. solium sera Abs in human. The commercial blot used any of the six bands 50, 42, 39, 24, 21, 18 and 14 kDa to detect T. solium sera Abs in human. Compared to the commercial blot, whose sensitivity and specificity was 98.00% and 100%, respectively, the crude antigen EITB had a sensitivity of 19.44% and specificity of 85.48%. The crude antigen EITB and Ab-ELISA tests showed significant difference (p<0.05), as the former detected more positives (25) compared to the latter (14) out of 199 samples tested.To our knowledge, this is the first study that attempted to establish an EITB from crude antigens. Most EITB that have been developed so far are based on purified antigens. The study demonstrated that the crude antigen EITB and Ab-ELISA tests are significantly less sensitive than the commercial Immunoblot test. Inspite of this, both the Ab-ELISA and EITB can be useful as screening tests in edemic areas before more sensitive and expensive tests are employed. Besides, Ab-ELISA tests have an advantage of giving the level of antibody titres in the patient’s blood, thus can be used to monitor the progress of the disease treatment. Future research should consider the use and evaluation of more immunogenic components of the cyst fluid or the use of purified or synthetic Ags, in an attempt to increase the test sensitivity.
Objetivo: Determinar la prevalencia de teniasis intestinal y seroprevalencia de cisticercosis de los vendedores de chicharrones de Lurín en Lima-Perú, y conocer sus características epidemiológicas, socioeconómicas y síntomas asociados con la parasitosis. Material y métodos: Se realizó un estudio transversal en vendedores de chicharrones del asentamiento humano “Julio C. Tello” de Lurín. Previo consentimiento informado de los participantes. Se utilizó una encuesta socioepidemiológica y se recolectó muestras de sangre para detectar anticuerpos específicos a Cisticerco (EITB) y de heces para la detección de coproantigenos de Taenia sp. (ELISA). Las muestras se procesaron en el Laboratorio de Cisticercosis del Instituto Nacional de Ciencias Neurológicas. El protocolo fue aprobado por el Comité de Ética de la Facultad de Medicina de San Fernando. Resultados: De 49 encuestados, el 89,8% participaba en la preparación de chicharrones y atención al público. El 81,6% refirió lavarse las manos siempre después de defecar, 65,3% refirió hacerlo antes de consumir alimentos. Hubo 41 muestras de sangre que resultaron negativas para cisticercosis. La detección de coproantigenos de Taenia sp. fueron negativos en todos los casos. No se encontró huevos de Taenia sp. en el examen de microsedimentación. Los locales contaban con servicios de agua y desagüe. Discusión: Las condiciones sanitarias y hábitos higiénicos adecuados reducirían el riesgo de infección. El consumo de carne de cerdo en forma de chicharrón podría no estar asociado a la trasmisión de este parásito. Conclusión: Los datos obtenidos indican que no existe teniasis ni cisticercosis en dicha población estudiada.
La cysticercose, parasitose tropicale négligée due à Taenia solium et dont le cycle concerne l’Homme et le porc, est responsable de 50 000 décès chaque année, principalement dans les pays du Sud. Notre travail de thèse a tenté d’explorer la situation épidémiologique de cette maladie dans la population porcine de Madagascar et de comprendre les déterminants expliquant sa prévalence dans le contexte épidémiologique et économique du pays. Dans un premier temps, nos enquêtes de prévalence en abattoir ont permis d’estimer une prévalence apparente de 4.6% [4.2-5.0%] au niveau national et une prévalence corrigée de 21.03% [19.18-22.87%] en tenant en compte de la sensibilité de la méthode (inspection vétérinaire par observation macroscopique). Dans un second temps nous avons modélisé le lien environnement-animal-homme dans le contexte des Hautes-Terres de Madagascar où l’élevage porcin est semi-intensifié mais où la cysticercose porcine reste endémique. Notre modèle multi-agents, développé sous Cormas, nous a permis de modéliser les comportements simplifiés des acteurs humains et animaux ainsi que les processus sanitaires et environnementaux. Une analyse de sensibilité multivariée nous a aidé à mieux comprendre les réactions du modèle vis-à-vis des paramètres d’entrée employés. Il s’est révélé sensible principalement à des paramètres décrivant (i) l’exposition des animaux à des aliments contaminés par des œufs de T. solium, notamment par la distribution d’aliments non contrôlés par l’éleveur et l’accès à un environnement contaminé, et (ii) la capacité infectante des œufs de T. solium, leur excrétion et leur survie dans l’environnement. Cette démarche exploratoire nous a permis ainsi d’identifier les paramètres d’importance mettant en lumière les besoins de recherche à mener pour renforcer la vraisemblance des résultats du modèle et nous aider à tester l’impact des scénarios de lutte contre la cysticercose dans des bassins de production porcine représentatifs de la réalité du pays.
The objective of this study was to identify and treat carriers of adult Taenia solium present in two rural Venezuelan communities through examination of faecal samples by coproscopical analysis, and by the application of a polyclonal and a monoclonal (VP-1) coproantigen ELISA. Both the polyclonal and monoclonal ELISA's were negative when tested with soluble extracts of adults of Ascaris lumbricoides, Hymenolepis nana and Trichuris trichura. The polyclonal ELISA was positive for soluble extracts adults of T. solium and T. saginata, whereas the monoclonal ELISA, which recognizes a glycoprotein, was restricted to T. solium, and was also negative with faecal samples from five cases of T. saginata adult infections. In the first community studied, Potrero Largo (Total population: 300), of 248 faecal samples examined, 2 individuals were positive for Taenia spp eggs by coproscopical analysis and the VP-1 ELISA, and yielded T. solium adults upon purging. In contrast, when the polyclonal coproAg ELISA was applied to the same 248 faecal samples, there were a considerable number of positives. Indeed, seven patients highly positive in the polyclonal ELISA did not yield a Taenia spp upon purging and were negative in the VP-1 ELISA. In the second community studied La Yuca (Total population 560), none of the 333 individuals who donated faeces was positive for Taenia spp eggs. Many, however, were infected with a range of intestinal helminth and protozoan parasites. A representative 76 of these faecal samples gave an unacceptable number of significant optical densities in the polyclonal coproAg ELISA. In contrast, all were negative in the VP-1 ELISA, thus providing an excellent negative control. These results with the VP-1 coproAg ELISA, although preliminary, justify further validation through the testing of more faecal samples from T. solium and T. saginata adult infected individuals.
Foodborne parasites are a source of human parasitic infection. Zoonotic infections of humans arise from a variety of domestic and wild animals, including sheep, goats, cattle, camels, horses, pigs, boars, bears, felines, canids, amphibians, reptiles, poultry, and aquatic animals such as fishes and shrimp. Therefore, the implementation of efficient, accessible, and controllable inspection policies for livestock, fisheries, slaughterhouses, and meat processing and packaging companies is highly recommended. In addition, more attention should be paid to the education of auditors from the quality control (QC) and assurance sectors, livestock breeders, the fishery sector, and meat inspection veterinarians in developing countries with high incidence of zoonotic parasitic infections. Furthermore, both the diagnosis of zoonotic parasitic infections by inexpensive, accessible, and reliable identification methods and the organization of effective control systems with sufficient supervision of product quality are other areas to which more attention should be paid. In this review, we present some examples of successful inspection policies and recent updates on present conventional, serologic, and molecular diagnostic methods for zoonotic foodborne parasites from both human infection and animal-derived foods.
Introduction:
Taenia solium cysticercosis is considered an emerging parasitic zoonosis of global importance due to its impact on both agriculture and public health in developing countries. Epidemiological information on human cysticercosis is limited in Nigeria. This study was conducted to determine the seroprevalence of human cysticercosis in areas of Kaduna metropolis, Nigeria, where small-holder pig farming is practiced.
Methodology:
A cross-sectional survey was conducted in Kaduna South and Chikun Local Government Areas of Kaduna metropolis, which are widely involved in small-holder pig farming and pork consumption. A total of 300 human sera were collected and tested for the presence of IgG antibodies to T. solium using an enzyme-linked immunosorbent assay (ELISA) technique. A structured questionnaire was used to identify risk factors in the population and was administered to the study population.
Results:
A total of 43 of 300 sera tested positive to IgG antibodies, indicating a cysticercosis prevalence of 14.3%. Method of pork preparation and history of epilepsy were found to be strongly associated with seropositivity. Epileptics in this study were two times more likely to be seropositive than non-epileptics. A large proportion (74.0%) of the population had very poor knowledge of cysticercosis, and knowledge of cysticercosis was strongly associated with method of pork preparation and respondents' occupations.
Conclusions:
A high seroprevalence of human cysticercosis was found in Kaduna South and Chikun Local Government Areas. The main risk and behavioral factors contributing to the high prevalence include poor knowledge of cysticercosis and lack of knowledge on proper pork preparation methods.
Protozoan zoonoses could be defined as “those protozoan diseases which are naturally transmitted between (other) vertebrate animals and man”. Diseases such as toxoplasmosis and cryptosporidiosis are worldwide in occurrence. Toxoplasma gondii, Cryptosporidium parvum and Sarcocystis suihominis are the most significant coccidian parasites affecting animals and man. Immunocompromised persons are always at higher risk of being infected with zoonotic parasites such as C. parvum, T. gondii, etc. Cryptosporidiosis is an emerging water-borne protozoan disease of public health significance. The parasite Sarcocystis suihominis is prevalent in pigs in Asian countries such as India and China. African trypanosomiasis, Chagas disease, leishmaniasis and zoonotic babesiosis are the important vector borne protozoan zoonotic diseases. African trypanosomiasis is still a priority zoonosis for the people in sub-Saharan Africa. The wild rodent P. leucopus acts as an important reservoir for B. microti human infections. Chagas disease is an important medical and economic concern in Latin America. Leishmaniasis has been reported from more than 80 countries.
Cestode Zoonoses could be defined as “those cestode diseases which are naturally transmitted between (other) vertebrate animals and man.” The zoonotic cestodes belonging to family Taeniidae are of paramount importance in the developing world. Most of the food producing animals viz. cattle, buffalo, sheep, goat and pigs along with some other mammals act as intermediate hosts for Echinococcus granulosus. Human beings could become infected after accidental consumption of Echinococcus species eggs shed in the faeces of the definitive carnivorous host/animal. Taeniasis is a true zoonotic infection (Euzoonoses) where pig and cattle act as intermediate host for Taenia solium and Taenia saginata, respectively and human beings act as definitive/final hosts. Neurocysticercosis is an important public health issue and is responsible for neurological disorders worldwide. Besides important animal and human health concern; the economic losses arising due to these infections are enormous. Coenurosis is a rare zoonosis and more than 100 human cases have been reported across the globe. Other important cestodes include parasites such as Diphyllobothrium latum and Spirometra mansoni. Different epidemiological trends have been reported across the globe for diphyllobothriasis. The parasite Dipylidium caninum can cause disease in domestic dogs, cats, some wild carnivores and occasionally man. Sparganosis is a rare cestode zoonosis that can infect man. The parasite has been recorded across the globe but is commonly found in eastern Asia. The important cestodes transmitted through food and water includes T. solium, E. granulosus and D. latum.
Taeniosis and cysticercosis are zoonotic diseases produced by Taenia saginata and Taenia solium. The adult tapeworms are parasites of human intestine and show a wide geographical distribution. Taenia asiatica, another tapeworm species, was described in Southeast Asia. The larval stages of these cestodes (metacestodes or cysticerci) cause cysticercosis; T. saginata causes bovine cysticercosis, T. asiatica larvae develop in the pig viscera, and T. solium is able to produce cysticercosis in both pig and man. When the parasite larva invades, the central nervous system (CNS) can provoke neurocysticercosis (NCC), one of the most frequent parasitic infections of human CNS. These diseases continue to cause health problems and livestock industry losses in areas where the parasites are endemic and also in non-endemic regions as a consequence of travel and migrations. There are few symptoms associated with taeniosis; in contrast, NCC (pleomorphic pathology) could be a life-threatening disease, depending on the location, number, stage of cysticerci, and the host immune response. Diagnosis of taeniosis is generally achieved by stool microscopic examinations, and the detection of cysticercosis is generally performed by neuroimaging and immunoassays. Both conventional coprological techniques and immunological assays show limitations, and new diagnostic tools have been developed, more specific and sensitive, such as specific monoclonal antibodies, recombinant antigens, synthetic peptides, and PCR. Considering the clinical impact, veterinary problems, and economic losses derived from taeniosis/cysticercosis, control programs have been implemented. In addition, several vaccine candidates have been characterized that could complement the control measures.
Las especies del género Taenia pertenecen a la clase Cestoda, orden Ciclophyllidea y a la familia Taeniidae. Sus formas adultas se desarrollan en el intestino del ser humano que actúa como único hospedador definitivo, y los estadios larvarios o cisticercos en los tejidos de los animales (cerdos, jabalíes y bóvidos), o el hombre. La teniasis humana se produce como consecuencia de la parasitación intestinal por especies del género Taenia. Las especies más comunes son Taenia solium y Taenia saginata, pero existe otra especie, Taenia saginata asiatica, que ha sido descrita de forma relativamente reciente (1991-1998). Mientras que las dos primeras tienen una distribución cosmopolita, la de T. saginata asiatica se circunscribe a Taiwan, Corea, Tailandia, Indonesia, China, Malasia y las Filipinas, con casos esporádicos en algunos países como España. La ingestión de huevos de T. saginata saginata y T. solium/T.saginata asiatica deriva en cisticercosis bovina y porcina, respectivamente. Los huevos de T. solium también pueden infectar a humanos dando lugar a la cisticercosis humana. No está claro que los huevos de T. saginata asiatica puedan infectar al hombre, aunque se piensa que dicha especie podría ser responsable de algunos casos de cisticercosis humana descritos en Asia. La parasitación por el género Taenia es una zoonosis cuyas tasas de prevalencia varían en función de diversos factores socio-económicos y culturales. El comportamiento humano resulta fundamental para su persistencia, ya que la contaminación con heces humanas de los terrenos posibilita la infección de los animales, y el hábito de ingerir carne cruda o poco cocinada cierra el ciclo permitiendo la infección humana por tenias adultas. La teniasis humana constituye un problema de salud pública que no afecta sólo a áreas endémicas, puesto que se ha observado un número creciente de casos en otras zonas geográficas.
Although it is widely assumed that both antigen and host immunological variability are involved in the variable intensity of natural porcine infections by Taenia solium (T. solium) cysticercis and success of immunodiagnostic tests vaccines, the magnitude of such combined variability has not been studied or measured at all. In this paper we report statistical data on the variability of the antibody response of naturally infected pigs against the antigens extracted from the vesicular fluids of their own infecting cysts (variance within pigs) and against antigen samples extracted from cysts of other cysticercotic pigs (variance among pigs). The variation between pigs was greater than the inter-pigs variations, which suggests that a concomitant immunity process prevents the establishment of cysts coming from a subsequent challenge. In so doing, we found that there is not a single antigenic band that was recognized by all hosts and that antigens varied among the cysts within the same pigs as well as among pigs. Our results may be valuable for the improvement of immunodiagnostic tests and of effective vaccines against naturally acquired porcine T. solium cysticercosis.
Intestinal parasites are highly prevalent in tropical areas and developing countries, but are also common in industrialised countries as well. Traditionally, their diagnosis has been made by microscopic examinations of the faeces of the patient. These have been shown to have poor sensitivity, require serial samples, are very time-consuming and require a specialised technique. In the last few years, advances in the molecular biology of these parasites and research into the specific immune response of the patient, has made it possible to develop more efficient detection systems that help the clinician, allow treatments to be followed up and make it easier to carry out epidemiological studies. Among these systems are the methods for detecting faecal antigens, which, in general, have good specificity and sensitivity; properties which make them a useful tool in microbiology laboratories.
Taeniasis/Cysticercosis: from conventional diagnosis to molecular diagnosis. The taeniasis is produced by the adult Taenia solium and T. saginata while cysticercosis is caused by the cysticerci in intermediaries hosts. The man can accidentally acquire cysticercosis by ingestion of contaminated food or water, which mainly affects the central nervous system and can lead to death. The diagnosis of taeniasis usually is accomplished through of coprologic examinations, while the diagnosis of cysticercosis is carried out mainly by imaging techniques and a wide variety of immunological tests. The coprologic methods show low sensitivity and not to distinguish between T. solium and T. saginata. Moreover, the immune conventional diagnostic methods have limitations, such as, low sensitivity and specificity, due to cross-react with other helminth parasites. Currently, are being implemented Molecular biology techniques that enable better diagnosis of these diseases, mainly PCR, PCR-RFLP and the use of recombinant antigens, and synthetic peptides, which have demonstrated good sensitivity and specificity for the diagnosis of Teniasis/Cysticercosis and whose manipulation is easy standardization and independent of material parasite, it is estimated that in the very near future may be used on a routine basis to supplement the conventional diagnosis of these diseases.
Species-specific identification of human tapeworm infections is important for public health purposes, because prompt identification of Taenia solium carriers may prevent further human cysticercosis infections (a major cause of acquired epilepsy). Two practical methods for the differentiation of cestode proglottids, (i) routine embedding, sectioning, and hematoxylin-eosin (HE) staining and (ii) PCR with restriction enzyme analysis (PCR-REA), were tested on samples from 40 individuals infected with T. solium (n = 34) or Taenia saginata (n = 6). Microscopic examination of HE staining of sections from 24 cases, in which conserved proglottids were recovered, clearly revealed differences in the number of uterine branches. Distinct restriction patterns for T. solium and T. saginata were observed when the PCR products containing the ribosomal 5.8S gene plus internal transcribed spacer regions were digested with either AluI, DdeI, or MboI. Both HE histology and PCR-REA are useful techniques for differentiating T. solium from T. saginata. Importantly, both techniques can be used in zones of endemicity. HE histology is inexpensive and is currently available in most regions of endemicity, and PCR-REA can be performed in most hospital centers already performing PCR without additional equipment or the use of radioactive material.
Immunodiagnostic tests for Taenia-specific faecal antigen based on polyclonal rabbit antisera against Taenia saginata or Taenia solium proglottid extracts in capture-type ELISA assays have been developed. Taenia-specific antigen was detected in detergent-solubilized faecal extracts from T. solium- and T. saginata-infected hosts. Coproantigen from T. solium-infected hamsters did not cross-react with faeces from rodents infected with Hymenolepis diminuta, H. citelli, H. microstoma, Necator americanus, Strongyloides ratti or Nematospiroides dubius and faeces from uninfected animals. When the T. saginata-capture ELISA was tested with faecal samples positive for T. solium antigen, no cross-reactions were obtained. However, faecal samples from humans infected with T. solium or T. saginata, including some with extremely low egg counts, were cross-reactive by either test. Nevertheless, considerably higher O.D. values were obtained with stool samples from Taenia patients compared to Hymenolepis nana-infected or uninfected individuals. Two individuals, infected with Taenia sp. and positive for coproantigens by ELISA, became antigen-negative 6 days after treatment with Niclosamide. The possibility of developing species-specific immunodiagnostic tests for human taeniasis through coproantigen detection is discussed.
A relatively simple and specific test has been developed to distinguish eggs of Echinococcus from those of other morphologically identical taeniid species. A specific anti-Echinococcus oncosphere monoclonal antibody was produced which binds in an indirect immunofluorescence test to egg-derived oncospheres of E. granulosus but not to those of other taeniid species, such as Taenia hydatigena, T. saginata, T. pisiformis, T. ovis, T. multiceps, or T. taeniaeformis. Specific fluorescence was obtained with oncospheres of E. granulosus derived from either hatch/activated viable eggs using artificial intestinal fluid or from hypochlorite/detergent treated eggs. The potential use of this test in the study of the transmission of Echinococcus in Turkana, Kenya, is discussed.
Cysticercosis results from ingestion of the eggs of the tapeworm Taenia solium. Reduction of the incidence of human and swine cysticercosis requires identification and treatment of individuals who carry the adult tapeworm. T. solium and Taenia saginata eggs cannot be differentiated on the basis of morphology; thus, in order to improve existing methods for the diagnosis of taeniasis, we have developed highly sensitive, species-specific DNA probes which differentiate T. solium and T. saginata. Recombinant clones containing repetitive DNA sequences which hybridize specifically with genomic DNAs from either species were isolated and characterized. T. solium-specific DNA sequences contained complete and truncated forms of a tandemly repeated 158-bp DNA sequence. An unrelated T. saginata DNA sequence was also characterized and shown to encode a portion of the mitochondrial cytochrome c oxidase I gene. T. solium- and T. saginata-specific DNA probes did not hybridize in dot blot assays either with genomic DNA from the platyhelminths Taenia hydatigena, Taenia pisiformis, Taenia taeniaeformis, Echinococcus granulosus, and Schistosoma mansoni or with genomic DNA from other eukaryotes, including Saccharomyces cerevisiae, Candida albicans, Cryptosporidium parvum, Entamoeba histolytica, Trypanosoma gambiense, Trypanosoma brucei, and Giardia lamblia, Caenorhabditis elegans, and human DNA. By using these T. solium and T. saginata DNA probes, a rapid, highly sensitive and specific dot blot assay for the detection of T. solium eggs was developed.
We developed a serologic assay to identify adult Taenia solium tapeworm carriers using excretory/secretory (TSES) antigens collected from in vitro cultured T. solium tapeworms. To identify taeniasis-specific antigens we used an immunoblot assay with serum samples from T. solium tapeworm carriers and cysticercosis patients. Antigens were identified that reacted with antibodies present in serum samples from taeniasis cases and not with those from cysticercosis patients. Using serum samples collected from persons with confirmed T. solium tapeworm infections, the test was determined to be 95% (69 of 73) sensitive. Serum samples (n = 193) from persons with other parasitic infections, including T. saginata tapeworm infections, do not contain cross-reacting antibodies to TSES, indicating that the assay is 100% specific. These data suggest that the immunoblot assay using TSES antigens can be used to identify persons with current or recent T. solium tapeworm infections and provides a new, important tool for epidemiologic purposes, including control and prevention strategies.
We have designed species-specific oligonucleotides which permit the differential detection of two species of cestodes, Taenia saginata and Taenia solium. The oligonucleotides contain sequences established for two previously reported, noncoding DNA fragments cloned from a genomic library of T. saginata. The first, which is T. saginata specific (fragment HDP1), is a repetitive sequence with a 53-bp monomeric unit repeated 24 times in direct tandem along the 1, 272-bp fragment. From this sequence the two oligonucleotides that were selected (oligonucleotides PTs4F1 and PTs4R1) specifically amplified genomic DNA (gDNA) from T. saginata but not T. solium or other related cestodes and had a sensitivity down to 10 pg of T. saginata gDNA. The second DNA fragment (fragment HDP2; 3,954 bp) hybridized to both T. saginata and T. solium DNAs and was not a repetitive sequence. Three oligonucleotides (oligonucleotides PTs7S35F1, PTs7S35F2, and PTs7S35R1) designed from the sequence of HDP2 allowed the differential amplification of gDNAs from T. saginata, T. solium, and Echinococcus granulosus in a multiplex PCR, which exhibits a sensitivity of 10 pg.
1. Intradermal tests with saline extracts of Ascaris and Dibothriocephalus were made upon 277 individuals of from one to sixty-five years of age, and with extracts of Taenia solium upon 20 persons. Reactions similar to those elicited in conditions of atopic hypersensitiveness (hay fever and asthma) were obtained.
2. Of 110 moderate and slight reactions 6 (or about 6 per cent) showed infestation in the excreta, as corroborated by findings. Of 53 individuals presenting marked reactions, 21 (or 40 per cent) revealed positive findings in the stools.
3. Of 309 cases giving negative reactions 1 was found to harbor Dibothriocephalus.
4. The absence of a positive reaction is not an absolute criterion of the absence of infestation with Dibothriocephalus, for one person infested with Dibothriocephalus remained negative to repeated tests.
5. Among those reacting to the Ascaris antigen were some individuals that were infested not with Ascaris lumbricoides, but with other members of the nematode family,—namely Uncinaria (hookworm), Trichiuris trichiuria, Oxyuris vermicularis, and Trichinella spiralis. This indicates a group reaction. Testing with the extract of Ascaris lumbricoides is sufficient therefore for the diagnosis of any nematode infestation.
6. The specificity of Dibothriocephalus latus and Taenia solium reactions was demonstrated.
7. In every case which gave a marked positive reaction, where the transfer of sensitivity passively to the normal human skin was undertaken, the transfer was successful even in individuals in whom active infestation could not be demonstrated, suggesting similarity to the same phenomenon observed in some atopic cases.
8. Constitutional reactions elicited in 3 asthmatic individuals as the result of intradermal tests with the Ascaris extract, indicates that extreme caution is necessary for routine testing, especially in atopic persons, with this type of extract.
9. A marked reaction was interpreted to indicate either the presence of parasites or recent infestation.
Le Riche P.D. and Sewell M.M.H. 1978. Differentiation of taeniid cestodes by enzyme electrophoresis. International Journal for Parasitology8: 479–483. Interspecific differences were shown by enzyme electrophoresis in thin starch gel between Echinococcus granulosus (from horses), Taenia hydatigena, T. multiceps, T. ovis, T. pisiformis, T. saginata, T. solium and T. taeniaeformis, Differences were seen with adenylate kinase, glucose phosphate isomerase, glutamate dehydrogenase, hexokinase and malate dehydrogenase. Multiple molecular forms of glucose phosphate isomerase were clear and most species could be differentiated by this enzyme alone.No differences attributable to anthelmintic effect were seen and zymogram patterns were identical for adult and cystic forms of each species. No differences were seen between specimens collected from various geographical locations.
Bursey C. C., Mckenzie J. A. & Burt M. D. B. 1980. Polyacrylamide gel electrophoresis in the differentiation of Taenia (Cestoda) by total protein. International Journal for Parasitology10: 167–174, Step-gradient polyacrylamide gels were used to examine total protein in 3 taeniid species. Preliminary investigations revealed that band patterns of different parts of the taeniid strobila were basically identical; hence, individual worms were useful for analysis regardless of their state of development when collected. Using Hymenolepis diminula as a control, the band pattern for each of Taenia taeniaeformis, T. macrocystis and T. pisiformis was found to be species specific with marked differences. The procedure was adapted for use under the more adverse conditions present in field laboratories. Small quantities of tapeworm material used in analysis also allows specific differentiation of single proglottids of Taenia spontaneously expelled from live hosts.
Antigens of Taenia solium can be demonstrated by ELISA technique in stool samples of tapeworm carriers. In order to isolate these immunodiagnostic components from stool, fecal samples of known T. solium carriers were subject to chromatographic purification procedures: immunoaffinity chromatography and a subsequent two-step high performance liquid chromatography yielded a 60-kDa protein that was shown to react in a Western blot with polyclonal anti-T. solium IgG. The protein isolated appeared to be the major antigenic component excreted with the feces of parasite hosts.
Specific IgG and IgA antibodies against adult Taenia pisiformis excretory/secretory antigen were detected in sera and saliva by enzyme-linked immunosorbent assay (ELISA) in experimentally infected dogs. IgG titres in serum and IgA in saliva corresponded with infection status, while serum IgA levels closely reflected faecal egg counts. The salivary IgA response was particularly raised and could have significant immunodiagnostic use for taeniasis in dogs.
Three ELISA assays, based on hyperimmune rabbit serum raised against adult cestode somatic antigen, were applied in this study for the detection of Taenia- and Echinococcus-specific antigens in host faeces. The first assay, using an antiserum against Taenia pisiformis antigen extract, was used in a time-course of T. pisiformis experimental infection in dogs. The assay was shown to be considerably more sensitive than microscopical detection of eggs in faeces. Antigen was present in faeces before patency and antigen levels were independent of T. pisiformis egg output. The second assay, involving a test for human taeniasis based on antibodies against T. solium, was applied in two field studies carried out in China and Guatemala. The test was highly specific, no false positive reactions occurred with human faecal samples and the test was capable of diagnosing individuals who would not have been detected by coproscopy or treatment to recover the tapeworm. A third assay was designed for E. granulosus and demonstrated 87.5% sensitivity and 96.5% specificity with samples from naturally and experimentally infected dogs with Echinococcus or Taenia infections. In both the human Taenia and canine Echinococcus studies antigen could be detected in faecal samples from infected hosts stored in 5% formalin for 6 months. Further refinements to these tests for field application are discussed.
An immunodiagnostic sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the detection of soluble Taenia saginata antigens in stool samples (copro-antigens) of infected humans, using affinity-purified polyclonal antibodies obtained from rabbits hyperimmunized with excretory/secretory antigens derived from T. saginata maintained in vitro. Investigation of operating characteristics showed very low cross-reactivity with crude antigens from helminths other than Taenia, including Dipylidium caninum and Diphyllobothrium latum. The specificity of the assay was 95% when testing stool samples from 100 persons who were either infected with Ascaris lumbricoides, Trichuris trichiura, hookworms, Enterobius vermicularis or Hymenolepis nana, or who had no intestinal helminthosis detected. Analysis of diagnostic sensitivity demonstrated that in 85% of 34 samples from 23 untreated persons with intestinal T. saginata infection (selected by previous proglottid and/or egg detection) copro-antigens were detected by the T. saginata ELISA. In the same samples, Taenia eggs were detected in 62%. Only 41% of the samples reacted positively in a heterologous T. hydatigena ELISA. Post-treatment control revealed a high concentration of T. saginata copro-antigens for 1-4 d after administration of niclosamide or praziquantel, and negative values 9-17 d after treatment. The Taenia copro-antigens remained detectable by ELISA even after storage of untreated faeces at 25 degrees C for at least 5 d.
Cysticercosis can be controlled by mass treatment of Taenia solium carriers in hyperendemic areas. An automated screening method suitable for mass application is required to determine the prevalence of taeniasis and the efficacy of its treatment, since existing methods of carrier detection are considered insufficient for this purpose. Thus, a biotin/avidin-enhanced enzyme-linked immunosorbent assay (ELISA) was designed, which detected T. solium antigens in supernatants of merthiolate-formalin preserved stool samples. The assay distinguished the nine T. solium carriers tested from 41 negative controls, but cross-reactivity with Taenia saginata was noted.
A size selected genomic DNA library was constructed using DNA extracted from Taenia saginata. The DNA was digested using the restriction enzyme EcoR1 under star conditions and the 2-4 kbase fraction, selected following sucrose density-gradient separation, was cloned in the bacteriophage lambda gt 10. A panel of cestode DNAs including Taenia saginata, Taenia solium, Taenia taeniaeformis, Taenia crassiceps, Echinococcus granulosus and DNAs of bovine, porcine and human origin were used in conjunction with hybridization analysis to identify two recombinant bacteriophages. The first probe, designated HDP1, reacted specifically with T. saginata DNA. The second, designated HDP2, reacted with DNA from both T. saginata and T. solium but not the other DNA samples and thus provided a general reagent for positive identification of fragments of Taenia spp. proglottides of human faecal origin. If used in conjunction the two DNA probes allow positive identification of T. saginata. In the clinical situation it is important to be able to distinguish T. saginata and T. solium infections and DNA probes such as these may be useful in such differentiation.
Antibodies specific for Echinococcus granulosus were affinity purified from dog serum on transfer blots containing putative serodiagnostic antigens. These antibodies and serum pools derived from dogs with E. granulosus infections were used to screen a lambda gt11 cDNA library constructed using E. granulosus protoscolex mRNA. Nine definitive antigenic clones were isolated and characterized, of which one (c10P1) gave strong specific reactions in plaque immunoassay with sera from E. granulosus infected dogs. These clones were all subcloned into the plasmid vector pGEX-1. Antigenicity of clones was confirmed in colony immunoassay and/or immunoblot. Glutathione S-transferase (GST) fusion proteins of individual subclones were produced in Escherichia coli, purified by affinity chromatography and evaluated in ELISA using sera from dogs with infections of E. granulosus, Taenia spp. or nematodes, and helminth-free dog sera. The GST fusion protein 10P1 showed a specificity of 100% in ELISA for diagnosis of E. granulosus infection in dogs despite its relatively low sensitivity. Further investigations aim to identify additional recombinant antigens and test 10P1 expressed in alternative expression systems to increase diagnostic sensitivity of the ELISA.
A sandwich-ELISA was developed for the detection of soluble Taenia hydatigena antigens in fecal samples of dogs. Affinity-purified polyclonal catching antibodies and alkaline phosphatase-conjugated detecting antibodies were employed, which had been obtained from rabbits hyperimmunized with excretory/secretory antigens derived from in vitro maintained adult Taenia hydatigena. The assay allowed the detection of 800 ng T. hydatigena antigen g-1 of feces as a lower limit. Six helminth-free dogs were each infected with 10 T. hydatigena cysticerci isolated from Swiss sheep. After prepatent periods ranging from 57 to 71 days, the dogs started to excrete Taenia eggs and/or proglottids. The ELISA detected Taenia antigens in all six dogs during the prepatent period starting individually between Day 18 and 45 post-infection (p.i.). Anthelmintic treatment of three dogs at Day 95 p.i. resulted in elimination of the cestodes and within the 5 following days in the disappearance of Taenia antigens from feces. The specificity of the assay was evaluated by testing crude antigens derived from helminths or bacteria. Four Taenia species showed cross-reactivity at concentrations of 5 micrograms protein ml-1. Conversely, no cross-reactions occurred with various antigen batches derived from Echinococcus granulosus, E. multilocularis, Dipylidium caninum, Mesocestoides corti, Diphyllobothrium sp., Toxocara canis and bacterial antigens (Salmonella and Escherichia). Moreover, fecal samples from dogs naturally infected with T. canis (n: 13), hookworms (n: 2), Trichuris vulpis (n: 13) and of 10 dogs with mixed infections with these three nematode groups were tested, and results confirmed the high degree of specificity. The Taenia antigens detectable by this ELISA remained immunologically stable in native feces stored at +25 degrees, +4 degrees or at -20 degrees C for at least 5 days.
A capture enzyme-linked immunosorbent assay (ELISA) for the detection of Hymenolepis diminuta coproantigen in detergent-solubilised faecal supernatants was developed. The assay was sensitive to 400 ng H. diminuta protein/ml faecal supernatant and to 30 ng/ml in PBS 0.3% Tween. Faecal antigen levels started to rise on day 7 post infection and peaked on day 20. Following drug treatment of infected rats with 10 mg/kg praziquantel, there was an initial steep rise in faecal antigen levels, followed by a decline to background levels for uninfected animals by day 7 post treatment. When assayed against faecal supernatants prepared from H. microstoma, H. citelli, Diphyllobothrium ditrenum, Necator americanus, Strongyloides ratti and Nematospiroides dubius infections as well as uninfected animals, all results from these groups were 2 SD below those for animals infected with H. diminuta. The application of such a test to important intestinal cestodiases in man is discussed.
An enzyme-linked immunoelectrotransfer blot (EITB) assay was developed for immunodiagnosing human cysticercosis. The assay
uses lentil-lectin, affinity-purified glycoprotein antigens. A battery of 532 serum and 46 cerebrospinal fluid (CSF) samples
(148 cases of parasitologically confirmed cysticercosis, 54 healthy controls, and 18 types of heterologous infections [376
cases]) were used to ascertain the assay's efficacy. All but three of the samples from cases of confirmed cysticercosis were
positive; none of the samples from healthy controls or heterologous infections reacted to any of the diagnostic bands. Thus,
the assay is 98% sensitive and 100% specific. We identified seven major glycoprotein bands that are commonly recognized by
virtually all serum and/or CSF samples from patients with confirmed cysticercosis. There was no significant difference in
test performance when CSF was compared with serum. The EITB assay is highly reproducible and simple to perform, and the reagents
(including the antigens blotted onto strips) are very stable.
A species-specific indirect immunofluorescence test using an anti-Echinococcus oncosphere monoclonal antibody (EgOH6-4E5) was applied to identify Echinococcus oncospheres released from taeniid eggs collected in environmental soil and water samples, and from perianal or faecal samples of naturally infected dogs, in northern Turkana, Kenya. The specificity of immunodetection of Echinococcus eggs by specific fluorescence of Echinococcus oncospheres from naturally infected dogs was 100% when compared to Taenia hydatigena infections, and a sensitivity of 73% was obtained in the detection of dogs infected with Echinococcus using perianal Scotch tape swabs. Taeniid eggs were recovered from various soil samples inside Turkana manyattas (settlements) and from waterhole samples. Some oncospheres obtained from taeniid eggs recovered from all sampled areas, but particularly from inside Turkana huts (akai) and from water samples from open waterholes used by the people and their livestock, reacted positively with the Echinococcus 4E5 monoclonal antibody. The potential importance of contamination of such sites with Echinococcus eggs is discussed in relation to the transmission of echinococcosis in this hyperendemic region of northern Kenya.
Serum antibody responses in feral or domesticated dogs naturally infected with Echinococcus granulosus or/and other common helminths were examined in an enzyme-linked immunosorbent assay (ELISA) using antigens prepared from E. granulosus protoscoleces or oncospheres. The ELISA using the protoscolex antigen was optimised with serums from experimental dogs monospecifically infected with E. granulosus or other helminth parasites, and helminth-free dogs. Anti-protoscolex antibody was detected in 16 of 22 (72.7%) serums from feral dogs with E. granulosus burdens ranging from 300 to 302,600 worms per dog. Seven serums from feral dogs which did not harbour E. granulosus at autopsy but which originated from an endemic hydatid region were tested using protoscolex antigen, and 1 serum gave a positive reaction. One hundred and two serums from dogs known never to have been infected with E. granulosus all gave negative reactions to protoscolex antigen. The sensitivity of the ELISA test proved to be superior to that which has been achieved by arecoline purging as a method of diagnosis for E. granulosus infection in dogs. For use of the assay in hydatid control or eradication campaigns, its sensitivity can be increased by choosing a lower absorbance discrimination value above which serums are regarded as having positive reactions. However, this does introduce positive reactions of some serums from dogs infected with helminths other than E. granulosus. In further development of the assay, use of defined recombinant antigens may improve both sensitivity and specificity.(ABSTRACT TRUNCATED AT 250 WORDS)
Six dogs reared helminth-free were divided into 2 groups. Four dogs were infected per os with 200,000 protoscoleces each of Echinococcus granulosus and 2 were kept as uninfected controls. All the dogs were kept together until 32 days after infection, when 1 infected dog was killed, its intestine removed and the contents examined to confirm that the infection with E. granulosus had been successful. The remaining 3 infected dogs were transferred to high security housing and their feces inspected daily to establish the time infections became patent. The infected and control dogs were bled every 5 days for 75 days from the time of infection and the sera were stored at -70 degrees C. Sera were tested by the enzyme-linked immunosorbent assay (ELISA) for antibodies to E. granulosus scolex excretory/secretory (ES) antigen, protoscolex antigen and oncosphere antigen. Antibodies to scolex ES antigen and protoscolex antigen were detected in the sera of infected dogs within 2 weeks of infection. Antibody titers rose rapidly and remained at a high level until the dogs were killed 75 days after infection. Antibodies in these sera did not cross react with antigens prepared from Taenia ovis, T. hydatigena, T. pisiformis, Ancylostoma caninum, Trichuris vulpis and Toxocara canis.
The excretory and secretory antigens from the evaginated scoleces of Taenia ovis were collected for 3 days in vitro, and used in an ELISA test to detect antibodies to T. ovis in the serum of dogs. When tested on sequentially collected sera, diagnostic ELISA values could be detected in many dogs 4 wk after infection, and remained for an average of a further 4 wk after worms were removed from dogs with an anthelmintic. Using an ELISA discriminant value that eliminated all false positives from 70 uninfected laboratory dog sera and from 57 uninfected farm dog sera, 54/62 true positives were found in sera from dogs infected with various numbers of T. ovis for various intervals. Sera from dogs infected with T. hydatigena gave 11/15 false positive reactions, whereas sera from 15 dogs infected with Echinococcus granulosus or 7 dogs infected with T. pisiformis were all negative. For T. ovis the test had a high repeatability, was not greatly influenced by the number of worms carried by the dog and higher titres were correlated with long-standing infections. Approximately 1,000 scoleces could be recovered from each experimentally infected sheep. Using the ELISA test with undiluted antigen and serum diluted 1:40, approximately 10 sera could be tested in duplicate with the excretions and secretions from each T. ovis scolex.
Groups of dogs reared free of both nematodes and cestodes were infected with Taenia hydatigena, Taenia pisiformis or Echinococcus granulosus. After infections with the Taenia spp became patent, dogs were purged to remove the worms. They were later reinfected and the second infections again removed by purging after patency. A group of 3 uninfected worm free dogs was kept as age-matched controls. The dogs were bled at intervals of 5 days and their serums tested for antibodies using the enzyme-linked immunosorbent assay (ELISA) with excretory/secretory (ES) antigens collected during in vitro incubation of evaginated scoleces (scolex ES antigen) and oncosphere antigens. Antibodies to scolex ES antigen were detected by 3 weeks after infection with each cestode species whereas antibodies to oncosphere antigen were not detected until about one week after eggs were found in the faeces of the infected dogs. Antibody responses to both oncosphere and scolex ES antigens decreased rapidly following removal of the worms by purging. Uninfected control dogs were invariably negative to both oncospheral and scolex ES antigens. There were cross-reactions between the serums from dogs infected with T. pisiformis and T. hydatigena when tested with scolex ES antigens, but oncospheral antigens showed a high degree of species specificity. Scolex ES antigens from E. granulosus were compared with those prepared from T. hydatigena and T. pisiformis for their ability to discriminate between antibodies in serums collected from dogs 31 and 32 days after infection with 100,000 protoscoleces of E. granulosus or dogs infected with Taenia spp.(ABSTRACT TRUNCATED AT 250 WORDS)
This chapter summarizes all significant matters concerning Taenia saginata (T. saginata) taeniasis and cysticercosis—that is, nomenclature, host relationships, structure and biology, clinical and therapeutic features, epidemiology and epizootiology, and prevention of infection. It considers some taxonomic problems and the hosts of T. saginata. The structure and biology of the adult worm, egg, onchosphere, and cysticercus is discussed. The clinical aspects of taeniasis are dealt in terms of symptomatology, clinical pathology, diagnosis, and treatment. Yomesan is the drug of choice for T. saginata infection in Man at present, and some suggestions are made for treatment with this and other drugs. The chapter discusses epidemiology, epizootiological, and losses due to taeniasis and cysticercosis. Losses are difficult to estimate, because infection is rarely fatal, but some figures are available for European, African, and American areas. Meat inspection is dealt with as a means of prevention, likewise serological diagnosis and the immunization of cattle. Sanitation is a matter discussed, its improvement, expensive but connected with higher standards of living.
In analogy to the immunological method for detecting the presence of cysticercosis in cattle we examined the applicability of the indirect immunofluorescence reaction as a technique for detecting taeniasis in man in 200 sera of tapeworm carriers and 150 sera of controls. Antibodies were found in the serum of most patients (112) infected by Taenia saginata, the test, however, showed widely different titer levels: in 44% of the patients we found false negative and in 1.3% false positive results. Serological investigations on the course of infection were carried out for 21 patients. Differing titer levels and titer variations show the limited applicability of this method in medicine, The importance and desirability of applying immunological techniques for diagnosing Taenia saginala are discussed.
The prevalence of Taenia saginata (Cestoda) among 146 predominantly Pokot tribesmen in western Kenya was studied in an attempt to assess the reliability of detecting infections by faecal examinations. firstly, a single faecal sample was microscopically examined after being processed by a standard ether sedimentation technique. Secondly, all subjects were treated with niclosamide and a purgative and the tapeworms were recovered. In this way the efficiency of diagnosing infections by faecal examinations was estimated. T. saginata eggs were found in the faeces of 68% of the men who were eventually found to be infected. Information was collected by interview from all subjects about whether they were or ever had been infected with tapeworms and about the form of treatment previously sought or taken. Eleven out of 25 men were apparently unaware of their tapeworm infections while no evidence of infection was found among 10 of the 24 reportedly infected men. A change in the pattern of treatment for tapeworms was reported which may have resulted in a recent decline in the prevalence of infection.
An analysis of Hymenolepis diminuta specific antigens in infected rat faeces was carried out. Using a capture type antibody sandwich ELISA assay based on a hyperimmune rabbit anti-worm somatic antisera it was demonstrated that, although antigen was present in faeces before patency, the onset of egg production led to a sharp increase in the levels of parasite antigen in the faeces. Levels of antigen in host faeces were independent of worm burden. Parasite eggs did not contribute significantly to faecal antigen levels. Western blot analysis indicated a number of highly specific antigens at around M(r) 69,000, M(r) 37,000, M(r) 50,000 and M(r) 27,000 with a low molecular weight smear at between M(r) 30,000 and M(r) 34,000 present in the faeces of H. diminuta infected rats. Some cross reaction occurred with an antigen of around M(r) 66,000 in the faeces of non H. diminuta infected rodents. Antibody activity against this antigen was removed by affinity adsorption of the antibody solution against normal rat faeces.
A dipstick dot ELISA for detection of Taenia-specific coproantigens was developed. The test was based on a sandwich ELISA using antibodies raised against adult Taenia solium. Antibodies were absorbed to nitrocellulose paper previously adhered to acetate plastic to form dipsticks. Once blocked with 5% skimmed milk and dried the antibody-coated dipsticks were stable for several weeks at room temperature. Both micro and dot ELISA formats were genus specific although the dot ELISA was less sensitive than the micro ELISA based on the same antiserum. During field studies, in which the majority of samples were tested in rural villages soon after collection, 3728 samples were tested. All samples were also examined by microscopy using formol ether concentration and individuals questioned to determine whether they were aware of being infected. After the initial diagnostic work individuals were treated with taeniacidal drugs for worm recovery. Use of the coproantigen test significantly increased the number of cases diagnosed. Of the 41 cases diagnosed by the three diagnostic techniques combined 31 were detected by the dipstick assay making it the most sensitive technique employed. The specificity of the dipstick assay was 99.9% with a positive predictive value of 88.6%. The combined diagnostic approach did not, however, diagnose all cases. The coproantigen test was fast and easy to use. Further improvements may make the dipstick test suitable for wide-scale use in field studies and diagnostic laboratories.
A microplate-type enzyme-linked immunosorbent assay for the detection of Taenia species antigen in human feces was tested in field studies undertaken in two Guatemalan communities. The test was based on immunoglobulin G antibodies from a rabbit hyperimmunized to Taenia solium proglottides. Comparison was made with microscopy and patient interviews as a means of diagnosis. The coproantigen test result was positive in 79 of the 1,582 fecal samples examined. Parasitologic confirmation was made in 55 of these cases. The coproantigen test was the most sensitive technique used, detecting 2.6 times as many confirmed cases of taeniasis as microscopy, which diagnosed 21 cases. Only one case was detected by interviewing. Microscopy revealed on false-negative coproantigen result. Mass treatment of the population did not result in the detection of any additional cases. Twelve coproantigen-positive results were categorized as unconfirmed and an additional 12 as putative false-positive results, giving an overall specificity of 99.2% for the coproantigen test. Of the 34 taeniid tapeworms identified to the species level, all were T. solium. The practicalities of the use of such a test in epidemiologic studies on human taeniasis are discussed.
The conditions which optimize detection of T. saginata antigens in faeces were subject of examination. The most appropriate appeared diluent of PBS + 0.3% Tween 20. The highest effectiveness was achieved using capturing and detecting antibodies to surface antigens in comparison with somatic and metabolic ones. Two step centrifugation and final dilution of samples 1:10 (w:v) were recommended. The stability of freezed faecal supernatants after the first centrifugation was limited to 2 months. The sensitivity of capture ELISA established in our examinations allow to signalize 1 ng/ml antigen in high absorbance values. The antigens recognized by the test had MW bigger than 100,000.
Stool samples were examined by capture ELISA for the presence of T. saginata antigens. The specimens were from 303 patients infected with T. saginata, 43 samples from individuals suffering from bacterial, fungal, protozoan and nematode infections and 36 ones deriving from uninfected persons. The samples were diluted 1:10 (w:v) in PBS + 0.35% Tween 20, centrifuged twice at 5000 g for 20 min at room temperature and resulting supernatant at 12,000 g for 30 min at 0 degree C. The capturing and detecting polyclonal antibodies were prepared in rabbits immunizing them with T. saginata surface antigens. The stool samples freshly obtained, stored at 4 degrees C not longer than 72 h, or kept at at -20 to -30 degrees C even for 24 months showed reliable results in ELISA. The samples kept for a long time at 4 degrees C, dried and covered with moult were negative in the test. All samples taken from patients infected with other than T. saginata parasites or uninfeced were negative.
There is relatively little epidemiological information on human intestinal taeniasis, particularly that due to Taenia solium. The current study involved analysis of data collected from four, rural communities in the Department of Jutiapa, Guatemala, between 1991 and 1994. Overall, 92 cases of intestinal taeniasis were identified, giving a mean prevalence of 2.7% (92/3399). Almost all (98%) of the 56 worms identified to species level were T. solium. Female subjects were significantly more likely to be infected than males, with a relative risk of 1.21 (95% confidence interval = 1.04-1.42; P < 0.04). Mean prevalence rose with age until the 30-39-year age cohort and declined thereafter. Cases were significantly clustered in households (P < 0.001). Most infections appeared to correspond to single worms. Only one multiple-worm infection was definitely detected, in an individual with at least seven T. solium tapeworms, all of which appeared to be sexually immature. To determine potential movements of infected subjects out of the villages, adult subjects in two of the villages were asked about their main place of employment; 9.7% (94/968) were recorded as working either in Guatemala City or the U.S.A. The possible epidemiological implications of these findings are discussed.
Two antibodies, one monoclonal and one polyclonal, were produced and used to identify Taenia solium eggs, using the enzyme-linked immuno-electrotransfer blot technique (EITB).
Different life-stages of Taenia solium and T. saginata, including eggs from gravid proglottids recovered, post-treatment, from patients infected with the tapeworms, and eggs of Diphyllobothrium pacificum and Hymenolepis nana from other patients were tested with these antibodies.
The monoclonal antibody only recognized the eggs and immature proglottids of T. solium. The polyclonal antibody, however, not only reacted with the eggs, cysticerci and immature proglottids of T. solium but also with the eggs and immature proglottids of T. saginata.
The sensitivity and specificity of the EITB were both 100% using the monoclonal antibody but only 78% and 60%, respectively, using the polyclonal antibody. Diagnostic bands for T. solium eggs corresponded to proteins of 22·5 kDa using the polyclonal antibody and 22·5–37 kDa using the monoclonal antibody.
Species-specific fluorescence was obtained with an anti- T. solium monoclonal antibody which bound to egg-derived oncospheres of T. solium but not to those of T. saginata.
Taenia solium taeniasis and cysticercosis are known to be endemic in Guatemala but no studies had been undertaken in rural communities where transmission was thought to occur. Two adjacent communities, Quesada and El Jocote, in the Department of Jutiapa were selected. The former had considerably better sanitary infrastructure than the latter. The seroprevalence of antibodies detected in humans by immunoblot to T. solium metacestode glycoprotein antigens was 10% and 17% and the prevalence of intestinal taeniasis was 1% and 2.8% in the two villages, respectively. Both of these represented statistically greater rates in El Jocote. Females were significantly more likely to be seropositive than males in the study as a whole. The majority of cases of intestinal taeniasis were due to T. solium. Cases of intestinal taeniasis were significantly more likely to be anti-cysticercus antibody-positive than the general population. Epilepsy was recorded in 2.8% and 2.9% of the populations of Quesada and El Jocote, respectively. Follow-up of this group and a group of asymptomatic individuals by computed tomography scan indicated that individuals with a history of seizures had a higher rate of abnormalities suggestive of neurocysticercosis. Cysts were present in the tongues of 4% of live pigs sampled in Quesada and 14% in El Jocote. In these two communities, which are probably representative of many others in Guatemala, T. solium appeared to be a significant public health problem.
The potential value of PCRs in the species-specific diagnosis of have been investigated, using samples of T. saginata and T. solium from different geographical areas. The PCRs examining inter-species differences were based on the sequence of the HDP2 DNA fragment, specific for T. saginata/T. solium, and the sequence of the rDNA internal transcribed spacer 1 and spacer 2 (ITS-1 and ITS-2). This PCR analysis of DNA isolates confirmed morphologic diagnosis and allowed the speciation of samples too small or fragmented for morphologic identification, with clear and consistent inter-species differences between T. saginata (twenty-two) and T. solium (three) geographical isolates. Possible intra-species genomic variability, within these species, was similarly studied through analysis of PCR amplification products (PCR-RFLP) and only encountered one exceptional T. saginata isolate from Kenya, which yielded a unique PCR-RFLP pattern, different from T. saginata DNA of Mexican (one sample) and Spanish (seven samples) origin.
A note on the skin reaction in Taenia infestation
- Ramsdell
Ramsdell, S., 1927. A note on the skin reaction in Taenia infestation. J. Parasitol. 14, 102?/105
Az echinococcis szerodiagnoztika-janak kerderehez
- S Babos
- I Nemeth
Babos, S., Nemeth, I., 1962. Az echinococcis szerodiagnoztika-janak kerderehez. Magyar Allatorvosok Lapja 17, 58?/60
Serological Studies on Taenia Saginata
- Machinicka Roguska
Machinicka Roguska, B., Zweirz, C., 1966. Serological Studies on Taenia Saginata. Wiad. Parazyt. 10, 467?/468
Diagnostic value of intradermal test with acid-soluble protein fractions in Taenia infections in man
- Slusarski
Slusarski, W., Zapart, W., 1971. Diagnostic value of intrader-mal test with acid-soluble protein fractions in Taenia infections in man. Acta Parasitol. Polonica 19, 445?/455
Development and characterisation of murine monoclonal antibodies to Echinococcus multilocu-laris adult worms and use for coproantigen detection Differentiation of taeniid cestodes by enzyme electrophoresis Haemagglutination reaction in people with Taenia saginata invasion
- H Kohno
- H Sakai
- M Okamoto
- M Ito
- Y Oku
- M Kamiya
Kohno, H., Sakai, H., Okamoto, M., Ito, M., Oku, Y., Kamiya, M., 1995. Development and characterisation of murine monoclonal antibodies to Echinococcus multilocu-laris adult worms and use for coproantigen detection. Jpn J. Parasitol. 44, 404 Á/412. Le Riche, P.D., Sewell, M.M.H., 1978. Differentiation of taeniid cestodes by enzyme electrophoresis. Int. J. Parasitol. 8, 479 Á/483. Machinicka Roguska, B., Zweirz, C., 1966. Serological Studies on Taenia Saginata. Wiad. Parazyt. 10, 467 Á/468. Machinicka Roguska, B., Zweirz, C., 1971. Haemagglutination reaction in people with Taenia saginata invasion. Wiad. Parazyt. 14, 27 Á/33.
Immu-noglobulin levels in patients infected with Taenia saginata
- K H Nepote
- Z S Pawlowski
- E J L Soulsby
Nepote, K.H., Pawlowski, Z.S., Soulsby, E.J.L., 1974. Immu-noglobulin levels in patients infected with Taenia saginata.