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Map showing the study area in the East Nile locality, as well as other localities of Khartoum state, Sudan
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Background:
The planorbid freshwater snails of the two genera, Biomphalaria and Bulinus -have been vigorously studied due to the role they play as intermediate hosts of schistosomiasis. In Sudan specifically, most studies have focused on the chemical and ecological control of the two genera, but few studies have looked at their biological control....
Similar publications
Only a fraction of the Biomphalaria and Bulinus snail community shows patent infection with schistosomes despite continuous exposure to the parasite, indicating that a substantial proportion of snails may resist infection. Accordingly, exterminating the schistosome intermediate snail hosts in transmission foci in habitats that may extend to kilomet...
The continuous morbidity and mortality caused by Schistosomiasis in Africa and the high cost of treatment necessitated a search for an alternative approach towards the control of the disease. A study on the infection rate of snail intermediate host of Schistosoma in Tsauni lake, Gidankwano and Garatu ponds in Bosso Local Government Area, Niger Stat...
Human schistosomiasis and soil-transmitted helminthiases (STHs) remain a major public health problem, responsible for significant morbidity and mortality in developing countries, despite availability of effective, safe and cheap drugs for their treatment. Long-term prevention of schistosomiasis and STHs has been difficult to achieve due to persisti...
Abstract Background Schsistosomiasis is endemic in sub-Saharan Africa. It is transmitted by intermediate host snails such as Bulinus and Biomphalaria. An understanding of the abundance and distribution of snail vectors is important in designing control strategies. This study describes the spatial and seasonal variation of B. globosus and Bio. pfeif...
Background: Schistosomiasis is endemic throughout all regions of Côte d’Ivoire, however, species of the intermediate snail host vary across bioclimatic zones. Hence, a deeper knowledge of the influence of climatic on the life history traits of the intermediate snail host is crucial to understand the environmental determinants of schistosomiasis in...
Citations
... The mean temperature fluctuates from 25 • C in December to 45 • C in May. The rainy season aligns with the period when the Nile experiences floods [33]. The AL-Sunut Forest Reserve can be found where the White and Blue Niles meet, between latitudes 15 • 34 ′ N-15 • 35 ′ N and longitudes 32 • 30 ′ E-32 • 29 ′ E. This forest spans about 164 hectares and is one of the last remaining urban forests in Sudan [34]. ...
... The mean temperature fluctuates from 25 °C in December to 45 °C in May. The rainy season aligns with the period when the Nile experiences floods [33]. The AL-Sunut Forest Reserve can be found where the White and Blue Niles meet, between latitudes 15°34′ N-15°35′ N and longitudes 32°30′ E-32°29′ E. This forest spans about 164 hectares and is one of the last remaining urban forests in Sudan [34]. ...
The present study aimed to understand visitors’ perceptions of the ecosystem service functions of the AL-Sunut Forest Reserve, as well as their recreational activities. Here, the impact of respondents’ socioeconomic status on visitors’ perceptions was statistically analyzed by t-tests and ANOVA (SPSS software v26). Meanwhile, multiple regression analysis was conducted to identify the relationships between factors shaping respondents’ perceptions of the AL-Sunut Forest during recreational activities. A total of 441 visitors were randomly selected and questioned through a questionnaire survey during February and March 2020. The results showed that visitors believed the recreational forest site was important and valuable and were willing to revisit it. Visitors also demonstrated a particular understanding of the ecosystem services provided by the forest ecosystem. There were significant differences in perceptions of ecosystem services among visitors of different backgrounds. The findings indicated that 79% of participants responded positively towards the importance of environmental education compared with any other education. In addition, 90% of respondents believed that habitats and natural resources such as forests must be protected. The results of the recreational activities of visitors showed that they acquired the most benefits when experiencing picturesque scenery and walking. Overall, the present findings can pave the way for decision-makers to develop a unique plan focusing on forests to implement an exhaustive approach to assessing the value of ecosystem services while emphasizing the general public’s welfare. The study’s results can also contribute to the future management of the AL-Sunut Forest.
... Khartoum State has a semi-arid climate, with yearly rainfall between 150 and 250 mm. The average monthly temperature ranges from 25 • C in December to 45 • C in May, and the Nile flood season coincides with the rainy season [39]. Al-Sunut Forest Reserve is strategically located at the confluence of the White and Blue Nile within the latitude of 15 • 34 N-15 • 35 N, longitude 32 • 30 E-32 • 29 E, covering an area of about 164 hectares, representing one of the rare remaining urban forests in Sudan [18]. ...
This study aims to present a methodological framework for estimating the recreational value as part of the ecosystem’s services provided by the Sudanese forests. The number of visitors ready to pay for the forest’s services has been analyzed using the individual travel cost method (ITCM). The data were collected using questionnaires with 640 visitors randomly participating at the forest site, and respondents’ results were analyzed using SPSS software v21. Further analysis of ITCM was performed using analysis of moment structure. The linear regression model is used to estimate the effects of variables, like socioeconomic variables, on the frequency of the visits to assess the recreational value of the forest site. The results showed that the consumer’s excess for each visitor was 21,500 Sudanese pounds (SDG), and travel costs, age, income, distance, and family size of visitors affect the recreational use of the site. Most of the visitors were students, with the majority of their ages ranging between 21 and 30. An additional discovery indicated that higher-income visitors were more willing to travel. These encouraging findings are a helpful guide for planning the future management of forests for recreational uses. This meant that forests offer great recreational value, which might help the Forestry Office ensure that natural forests are planned for and used sustainably.
... To augment this foundational intervention, it is important to monitor and ascertain the geographical distribution of freshwater snails. Furthermore, better snail surveillance provides essential data on freshwater biodiversity, and environmental management needs, against a background of wider climate change and anthropogenic impacts [13,14]. ...
Repeated malacological surveys were conducted in Chikwawa and Nsanje Districts in the Lower Shire River, Southern Region of Malawi to alert to and to characterize populations of Biomphalaria pfeifferi . Sampling took place across a total of 45 sites, noting water conductivity, pH, temperature, total dissolved salts (TDS) and geographical elevation. Subsequently, the presence or absence of snails was predicted upon physiochemical and environmental conditions in Random Forest modelling. A concurrent molecular phylogenetic analysis of snails was conducted alongside molecular xenomonitoring for the presence of pre-patent infection with Schistosoma mansoni . Water conductivity, TDS and geographical elevation were most important in predicting abundance of snails with water temperature and pH of slightly less important roles. Our first alert with geographical modelling of populations of B. pfeifferi in the Lower Shire River is a critical step towards improving understanding of the transmission of intestinal schistosomiasis and a more solid foundation towards developing complementary strategies to mitigate it.
... These parasitic trematodes can be dangerous to public health and cause socioeconomic issues in many tropical and subtropical regions (Tookhy et al. 2022;Prasopdee et al. 2015). Since freshwater snails of the family Lymnaeidae are involved in the life cycle of various trematodes with significant biomedical and veterinary implications, they attract a lot of attention (Saijuntha et al. 2021;Mohammed et al. 2016; Bargues et al. 2011). The cercarial stage is a free-living stage that lives inside the snail's intermediate host and emerges when it is entirely mature. ...
... In this study, mixed infections of two or more cercarial types in R. rubiginosa were also detected in 0.1% (8/836) of snails. Mixed infection of two cercariae types in a single snail also reported by Mohammed et al. (2016) in East Nile locality of Khartoum, Sudan. Overall, mixed infections of cercariae in a single snail was less in the present study, suggesting that antagonistic interactions between various trematodes could be present which limiting or preventing the establishment of some trematode species (Keeney et al. 2008;Sousa 1992). ...
Lymnaeid snails play a crucial role in the transmission of trematode cercariae as an intermediate host that can infect humans, ruminants like buffalo, and other animals, resulting in serious economic losses. The purpose of the study was to identify the morphological and molecular characteristics of snails and cercariae collected from water bodies near buffalo farms that were integrated with palm oil in Perak, Malaysia. The presence or absence of snails in 35 water bodies was examined via cross-sectional study. From three marsh wetlands, 836 lymnaeid snails were gathered in total. Each snail’s shell was morphologically identified to determine its family and species. The cercarial stage inside each snail’s body was observed using the crushing method and trematode cercariae types were determined. In addition, the target gene Cytochrome c oxidase subunit 1 (Cox1) and the ribosomal internal transcribed spacer 2 (ITS2) region were used to identify the snail species and cercarial types according to the species level. The findings indicated that the collected snails belong to the family lymnaeidae and Radix rubiginosa species. In snails, the cercarial emergence infection rate was 8.7%. Echinostome, xiphidiocercariae, gymnocephalous, brevifurcate-apharyngeate distome cercariae (BADC), and longifurcate-pharyngeal monostome cercariae (LPMC) are the five morphological cercarial types that were observed. The cercariae were identified using morphological and molecular techniques, and they are members of the four families which are Echinostomatidae, Plagiorchiidae, Fasciolidae, and Schistosomatidae. Interestingly, this is the first study on R. rubiginosa and several trematode cercariae in Perak water bodies near buffalo farms that are integrated with palm oil. In conclusion, our research shown that a variety of parasitic trematodes in Perak use R. rubiginosa as an intermediate host.
... Relative abundance of freshwater molluscs species in Kafrelsheikh district during 2019/2020. The water speed, water pollution level, and the use of agricultural chemicals have been reportedly affected the distribution and population density of snail species [24][25][26], this may explain the variations in snail density in agricultural irrigation and drainage canals. Previous surveys have been conducted in Egypt and resulted in 13 species of freshwater snails belonging to 9 families of class Gastropoda have been found in Qena Governorate [8], 12 sp. ...
Snails are invertebrate organisms belonging to the Gastropoda class inhabit freshwater and other aquatic environments worldwide, some of them act as intermediate hosts for trematode and schistosome parasites. This study aimed to survey and compare the seasonal abundance of freshwater molluscs species in agricultural irrigation and drainage canals in Kafrelsheikh, Egypt. Also, the distribution of the intermediate host snails and their predators in this area was studied. The molluscs samples were collected from irrigation and agricultural drainage canals of three sites in Kafrelsheikh district from June 2019 to May 2020. Seventeen aquatic molluscs species belonging to 8 families and 2 classes were recorded in the Kafrelsheikh district. The species richness shows 16 and 14 molluscs species in agricultural irrigation and drainage canals, respectively. All species belonging to class Gastropoda except for Corbicula fluminalis and Mutela rostrata which belonging to class Bivalvia. The most abundant freshwater snail species in irrigation canals were Melanoides tuber-culate, Physa acuta, Helisoma duryi, and Bellamya unicoior, and in agricultural drainage canals were P. acuta, B. unicoior, L. carinatus, and Valvata nilotica. On contrary, Planorbis planorbis was non-detected in irrigation canals, while Theodoxus niloticus, Thi-ara scabra, and the bivalve, M. rostrata were non-detected in agricultural drainage canals. Thiara scabra was firstly recorded in Kafrelsheikh province. It could be concluded that the freshwater snail species and their population density were more diverse and numerous in irrigation canals compared to agricultural drainage ones and significantly depended on the time of the year.
... Sampling was undertaken by two experienced field collectors using snail scoops. The scoops were composed of a wire mesh measuring 1.5 × 1.5 mm, supported on an iron frame (40 × 30 cm), and mounted on a 1.5-m-long iron handle [28]. At each site, the investigators collected all snails found in a radius of approximately 2 m over a permitted search time of half an hour. ...
Sound knowledge of the local distribution and diversity of freshwater snail intermediate hosts and the factors driving the occurrence and abundance of them is crucial to understanding snail-borne parasitic disease transmission and to setting up effective interventions in endemic areas. In this study, we investigated the freshwater snails, water quality parameters, physical characteristics of habitats, predators and competitors, and human activity variables at 102 sites during December 2018 and August 2019 in Shenzhen and adjacent areas in China. We used decision tree models and canonical correspondence analysis to identify the main environmental and biotic factors affecting the occurrence and abundance of snail species. A total of nine species of snail were collected throughout the study area, with Biomphalaria straminea, Sinotaia quadrata, and Physella acuta being the most predominant species. Our study showed that the most important variables affecting the abundance and occurrence of snail species were the presence of predators and competitors, macrophyte cover, chlorophyll-a, substrate type, river depth, and water velocity. In terms of human activities, snail species occurred more frequently and in larger numbers in water bodies affected by human disturbances, especially for sewage discharge, which may reduce the occurrence and abundance of snail predators and competitors. These findings suggest that proper management of water bodies to reduce water pollution may increase the abundance of snail predators and competitors, and should be considered in integrated snail control strategies in the study area.
... The intermediate host of rumen flukes is freshwater/mud snails such as Planorbis, Lymnaea, and Bulinus (Iqbal et al., 2013;Javed Khan et al., 2006;Taylor et al., 2007). Lymnaeid snails, the intermediate host of rumen fluke, play an essential role in the epidemiology of rumen fluke (Bargues & Mas-Coma, 2005 (Dodangeh et al., 2019;Dung et al., 2013;Martin & Cabrera, 2018;Mohammed et al., 2016). Therefore, rumen fluke is found at high prevalence in most tropical and sub-tropical countries such as Bangladesh, Thailand, Indonesia, and India (Azam et al., 2012;Kaewnoi et al., 2020;Hambal et al., 2020;Malathi et al., 2021), particularly in locations where the climatic and environmental conditions are favourable for the intermediate host snail's survival and multiplications (Gordon et al., 2013;Taylor et al., 2007). ...
Rumen fluke is a parasitosis that infects ruminant animals across a wide geographical range of countries. It is a severe infection in temperate and tropical climate regions of Asia, Australia, Africa, and Europe, which cause significant economic losses. In this review, the available information to date on rumen fluke species infecting cattle and buffaloes in Asian countries is evaluated. The citation search was performed through specific keywords, literature published from 1964 to 2021, retrieved from electronic databases: Scopus, Web of Science, Pub Med, Education Resources Information Center (ERIC), Science Direct, Elsevier, and Google Scholar. Twenty-six (26) rumen fluke species belonging to two families: Paramphistomidae 61.5% (16/26) and Gastrothylacidae 38.4% (10/26), were reported in cattle and buffaloes in fourteen Asian countries. Paramphistomum cervi and Cotylophoron cotylophorum are the most prevalent species with broader distribution in countries than the other genera. The coprological prevalence varies from 0.8% to 98.17% and 0.86% to 78.4% in cattle and 782 Pertanika J. Trop. Agric. Sci. 45 (3): 781-803 (2022) buffaloes, respectively. The prevalence of rumen fluke by fluke counts method range between 6.45% to 90.6% and 4.29% to 75.07% in cattle and buffaloes, respectively. The sedimentation method and fluke count are reliable tests for detecting rumen fluke in live and slaughtered animals. In conclusion, the rumen fluke should be considered a critical production disease that affects cattle and buffaloes in Asia. Further studies are necessary to determine the rumen fluke-snail associations, develop diagnostic tests to detect prepatent infections in the definitive host, determine the economic importance of rumen fluke, and determine the efficacy of different anthelmintic in the treatment of patent infections in the definitive host.
... Despite the widespread distribution of Bulinus throughout Africa, southern Europe, and the Middle East (Brown, 1994) and the diverse trematode communities that are hosted by Bulinus species (Chingwena et al., 2002;Loker et al., 1981;Mohammed et al., 2016), the impact of trematode infections on Bulinus shell phenotype remains poorly understood. Indeed, only laboratory analyses investigating morphological changes induced by Schistosoma margrebowei on Bulinus natalensis (Raymond and Probert, 1993) and by Schistosoma haematobium on Bulinus truncatus, Bulinus senegalensis and Bulinus globosus (Fryer et al., 1990) have been published. ...
... Using cercarial shedding and morphological identification, Loker et al. (1981) reported infections by 2-7 parasite morphotypes with a prevalence ranging from 2.5 to 9.7% for several species of Bulinus from Tanzanian streams (sample size ranging from 186 to 1503 snails). Chingwena et al. (2002) analysed 4080 B. tropicus collected from streams and dams in Zimbabwe, 13.1% of which were infected by combinations of 5 morphotypes of cercariae, and Mohammed et al. (2016) reported that 46.2% of 1403 B. truncatus collected form irrigation canals in Sudan were infected by an assemblage of 8 morphotypes of cercariae. Beyond sampling size, various factors likely drive variation in observed trematode species richness among snail populations, including differences in susceptibility to infection among snail species and final host species richness (Hechinger and Lafferty, 2005). ...
Trematodes can increase intraspecific variation in the phenotype of their intermediate snail host. However, the extent of such phenotypic changes remains unclear. We investigated the influence of trematode infection on the shell morphology of Bulinus tropicus, a common host of medically important trematodes. We focused on a snail population from crater lake Kasenda (Uganda). We sampled a single homogeneous littoral habitat to minimize the influence of environmental variation on shell phenotype, and barcoded snails to document snail genotypic variation. Among the 257 adult snails analysed, 99 tested positive for trematode infection using rapid-diagnostic PCRs. Subsequently we used high-throughput amplicon sequencing to identify the trematode (co-)infections. For 86 out of the 99 positive samples trematode species delineation could discriminate among combinations of (co-)infection by 11 trematode species. To avoid confounding effects, we focused on four prevalent trematode species. We performed landmark-based geometric morphometrics to characterize shell phenotype and used regressions to examine whether shell size and shape were affected by trematode infection and the developmental stage of infection (as inferred from read counts). Snails infected by Petasiger sp. 5, Echinoparyphium sp. or Austrodiplostomum sp. 2 had larger shells than uninfected snails or than those infected by Plagiorchiida sp. Moreover, the shell shape of snails infected solely by Petasiger sp. 5 differed significantly from that of uninfected snails and snails infected with other trematodes, except from Austrodiplostomum sp. 2. Shape changes included a more protuberant apex, an inward-folded outer apertural lip and a more adapically positioned umbilicus. Size differences were more pronounced in snails with ‘late’ infections (>25 days) compared to earlier-stage infections. No phenotypic differences were found between snails infected by a single trematode species and those harbouring co-infections. Further work is required to assess the complex causal links between trematode infections and shell morphological alterations of snail hosts.
... Particularly, if there is no other alternative in terms of water and sanitation improvement, community residents should be guided not to contact water during the intensive cercarial shedding time. Second, stakeholders in the public and private sectors, such as organizations in the agricultural and fishery sector and sugar cane companies, should be clearly informed of this, and they should strive to improve water and sanitation facilities for farmers, fishers, and sugar cane workers, who mainly work around infested water bodies, such as irrigation canals and rivers [48]. Third, it is necessary to develop an enabling environment to prevent people from coming into contact with infested water and to control snails in a sustainable manner. ...
Background:
The epidemiology of schistosomiasis transmission varies depending on the circumstances of the surrounding water bodies and human behaviors. We aimed to explore cercarial emergence patterns from snails that are naturally affected by human schistosomiasis and non-human trematodes. In addition, this study aimed to explore how schistosomiasis infection affects snail survival, reproduction, and growth.
Methods:
We measured the survival rate, fecundity, and size of Biomphalaria pfeifferi snails and the cercarial rhythmicity of S. haematobium and S. mansoni. The number of egg masses, eggs per egg mass, and snail deaths were counted for 7 weeks. The survival rate and cumulative hazard were assessed for infected and non-infected snails.
Results:
S. haematobium and S. mansoni cercariae peaked at 9:00-11:00 a.m. Infection significantly reduced the survival rate of B. pfeifferi, which was 35% and 51% for infected and non-infected snails, respectively (p = 0.02), at 7 weeks after infection. The hazard ratio of death for infected snails compared to non-infected snails was 1.65 (95% confidence interval: 1.35-1.99; p = 0.01).
Conclusions:
An understanding of the dynamics of schistosomiasis transmission will be helpful for formulating schistosomiasis control and elimination strategies. Cercarial rhythmicity can be reflected in health education, and the reproduction and survival rate of infected snails can be used as parameters for developing disease modeling.
... To avoid collinearity in the multivariable models, the covariance of the selected variables was investigated pairwise to determine the correlation among the variables. Since the patency of trematodes takes around 4 weeks in a snail (Sorensen and Minchella, 2001;Mohammed et al., 2016), a lag period of 4 weeks is included in data analysis in the logistic regression analyses. The prevalence of all trematode cercariae in B. s. goniomphalos was calculated as a percentage for each cercarial type. ...
Several trematodes including Opisthorchis viverrini utilize Bithynia siamensis goniomphalos as a snail intermediate host in their life cycles. In order to capture a comprehensive range of host–parasite interactions and their transmission dynamic patterns, B. s. goniomphalos were sampled monthly over 4 consecutive years in an irrigated paddy-field habitat in northeast Thailand. Using a standard cercarial shedding method, a high diversity of trematodes (17 types) was recovered. Virgulate xiphidiocercariae were the most prevalent (7.84%) followed by O. viverrini (0.71%). In addition to seasonal and environmental factors, the quantity of irrigation water for rice cultivation correlated with transmission dynamics of trematodes in B. s. goniomphalos . The peak prevalence of all trematode infections combined in the snails shifted from the cool-dry season in 2010–2012 to the hot-dry season in 2013 associated with an increasing quantity of water irrigation. A low frequency of mixed trematode infections was found, indicating that the emergence of virgulate cercariae, but not of O. viverrini , was negatively impacted by the presence of other trematodes in the same snail. Taken together, the observed results suggest that interactions between host and parasite, and hence transmission dynamics, depend on specific characteristics of the parasite and environmental factors including irrigated water for rice cultivation.
