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Transactions of the Royal Society of... 1980Some biological features of F1 hybrids between South African strains of Schistosoma haematobium and S. mattheei are described and compared with those of both parental...
Some biological features of F1 hybrids between South African strains of Schistosoma haematobium and S. mattheei are described and compared with those of both parental species. The distinctive patterns of the G6PD and PGM isoenzymes, resolved by isoelectric focusing, of both species and of the hybrid are defined and the results of enzyme analyses of parasites isolated from human infections in the Transvaal are reported. These show that hybridization does occur naturally in man and that the shape of the eggs produced is not necessarily a guide to the genetic constitution of the enclosed larvae. The experimentally produced F1 hybrids exhibit heterosis in their increased infectivity to both snails and hamsters, in their more rapid growth and earlier maturation and in the increased daily egg production per female worm when compared with both of the parental species. The possible practical implications of this are discussed.
Topics: Animals; Cricetinae; Humans; Hybridization, Genetic; Isoelectric Focusing; Isoenzymes; Schistosoma; Schistosoma haematobium; Snails
PubMed: 7434427
DOI: 10.1016/0035-9203(80)90091-7 -
Parasites & Vectors Mar 2019Accurate identification of schistosome species infecting intermediate host snails is important for understanding parasite transmission, schistosomiasis control and...
BACKGROUND
Accurate identification of schistosome species infecting intermediate host snails is important for understanding parasite transmission, schistosomiasis control and elimination. Cercariae emerging from infected snails cannot be precisely identified morphologically to the species level. We used molecular tools to clarify the distribution of the Schistosoma haematobium group species infecting bulinid snails in a large part of Côte d'Ivoire and confirmed the presence of interspecific hybrid schistosomes.
METHODS
Between June 2016 and March 2017, Bulinus snails were sampled in 164 human-water contact sites from 22 villages of the northern and central parts of Côte d'Ivoire. Multi-locus genetic analysis (mitochondrial cox1 and nuclear ITS) was performed on individual schistosome cercariae shed from snails, in the morning and in the afternoon, for species and hybrid identification.
RESULTS
Overall, 1923 Bulinus truncatus, 255 Bulinus globosus and 1424 Bulinus forskalii were obtained. Among 2417 Bulinus screened, 25 specimens (18 B. truncatus and seven B. globosus) shed schistosomes, with up to 14% infection prevalence per site and time point. Globally, infection rates per time point ranged between 0.6 and 4%. Schistosoma bovis, S. haematobium and S. bovis × S. haematobium hybrids infected 0.5%, 0.2% and 0.4% of the snails screened, respectively. Schistosoma bovis and hybrids were more prevalent in B. truncatus, whereas S. haematobium and hybrid infections were more prevalent in B. globosus. Schistosoma bovis-infected Bulinus were predominantly found in northern sites, while S. haematobium and hybrid infected snails were mainly found in central parts of Côte d'Ivoire.
CONCLUSIONS
The data highlight the necessity of using molecular tools to identify and understand which schistosome species are transmitted by specific intermediate host snails. The study deepens our understanding of the epidemiology and transmission dynamics of S. haematobium and S. bovis in Côte d'Ivoire and provides the first conclusive evidence for the transmission of S. haematobium × S. bovis hybrids in this West African country. Trial registration ISRCTN, ISRCTN10926858. Registered 21 December 2016; retrospectively registered (see: http://www.isrctn.com/ISRCTN10926858 ).
Topics: Animals; Bulinus; Cote d'Ivoire; Female; Humans; Male; Molecular Typing; Phylogeography; Schistosoma haematobium; Schistosomiasis haematobia; Seasons
PubMed: 30890180
DOI: 10.1186/s13071-019-3381-3 -
Parasite (Paris, France) 2014Although schistosomiasis has been a public health issue in Gabon for nearly a century, little is known about its current transmission dynamics. We analyzed the... (Comparative Study)
Comparative Study
Although schistosomiasis has been a public health issue in Gabon for nearly a century, little is known about its current transmission dynamics. We analyzed the chronobiology of 137 cercarial emission profiles of Schistosoma haematobium from Libreville, the capital of Gabon, located in an open area for schistosomiasis. We found that 88% of the cercariae were shed between 11 a.m. and 3 p.m. and that the average pattern was of circadian type, with the average peak at 1 p.m., and representing 27% of the total number of cercariae of the day. The rhythms of emergence may be associated with environmental pressures on the parasite, especially those related to their definitive hosts.
Topics: Animals; Bulinus; Cercaria; Circadian Rhythm; Environment; Gabon; Gerbillinae; Light; Schistosoma haematobium
PubMed: 24502943
DOI: 10.1051/parasite/2014004 -
Parasites & Vectors Oct 2015Effective control of schistosomiasis remains a challenging problem for endemic areas of the world. Given knowledge of the biology of transmission and past experience...
BACKGROUND
Effective control of schistosomiasis remains a challenging problem for endemic areas of the world. Given knowledge of the biology of transmission and past experience with mass drug administration (MDA) programs, it is important to critically evaluate the likelihood that MDA programs will achieve substantial reductions in Schistosoma prevalence. In implementing the World Health Organization Roadmap for Neglected Tropical Diseases it would useful for policymaking to model projections of the status of Schistosoma control in MDA-treated areas in the next 5-10 years.
METHODS
Calibrated mathematical models were used to project the effects of different frequency and coverage of MDA for schistosomiasis haematobia control in present-day endemic communities, taking into account uncertainties of parasite biology and input data. The modeling approach in this analysis was the Stratified Worm Burden model developed in our earlier works, calibrated using data from longitudinal S. haematobium control trials in Kenya.
RESULTS
Model-based simulations of MDA control in typical low-risk and higher-risk communities indicated that infection prevalence can be substantially reduced within 10 years only when there is a high degree of community participation (>70 %) with at least annual MDA. Significant risk for re-emergence of infection remains if MDA is suspended.
CONCLUSIONS
In a stable (stationary) ecosystem, Schistosoma reproduction and transmission are sufficiently robust that the process of human infection continues, even under pressure from aggressive MDA. MDA alone is unlikely to interrupt transmission, and once mass treatment is suspended, the prevalence of human infection is likely to rebound to pre-control levels over a period of 25-30 years. MDA success in achieving very low levels of infection prevalence is highly dependent on treatment coverage and frequency within the local human population, and requires that both adults and children be included in drug delivery coverage. Ultimately, supplemental snail control and significant improvements in sanitation will be required to achieve full control of schistosomiasis by elimination of ongoing Schistosoma transmission.
Topics: Adult; Africa; Animals; Anthelmintics; Female; Humans; Male; Models, Theoretical; Praziquantel; Schistosoma haematobium; Schistosomiasis haematobia; Time Factors
PubMed: 26489408
DOI: 10.1186/s13071-015-1144-3 -
Parasitology Research Mar 1999Planorbarius metidjensis measuring 2 or 3 mm in diameter and originating from three populations in the Agadir province (Ida Ou Gnidif, Imouzzer, and Sidi Belkacem) were...
Schistosoma haematobium: comparative studies on the characteristics of infection in three populations of Planorbarius metidjensis from the Agadir province in South Morocco.
Planorbarius metidjensis measuring 2 or 3 mm in diameter and originating from three populations in the Agadir province (Ida Ou Gnidif, Imouzzer, and Sidi Belkacem) were experimentally infected with Schistosoma haematobium to determine if the complete larval development of the parasite might be ensured by any snail population of the Agadir province and to compare the general characteristics of infection. No significant difference between the three populations was noted in the survival rates of snails when the first shedding occurred or in the prevalence of infection. The mean duration of the shedding period was significantly higher in the Imouzzer population (111 days versus 53-58 days). The total number of cercariae shed per mollusc was significantly lower in the Ida Ou Gnidif planorbids (1,398/snail versus 3,346 and 3,343/snail in the other 2 groups). The same rhythm in daily cercarial production was noted in the three snail groups, with the periodicity being 18-20 days. Despite some differences in parasite development between the three snail populations, the different populations of P. metidjensis can ensure the complete development of S. haematobium and maintain local transmission in the South of Morocco.
Topics: Animals; Host-Parasite Interactions; Larva; Morocco; Schistosoma haematobium; Snails
PubMed: 9951968
DOI: 10.1007/s004360050540 -
Sultan Qaboos University Medical Journal Aug 2018This study aimed to assess the efficacy of praziquantel in reducing urinary schistosomiasis prevalence, parasite burden and morbidity rates among a previously reported...
OBJECTIVES
This study aimed to assess the efficacy of praziquantel in reducing urinary schistosomiasis prevalence, parasite burden and morbidity rates among a previously reported sample of -infected children. In addition, predisposing factors for reinfection one year post-treatment were also determined.
METHODS
This prospective follow-up study was conducted between March 2014 and February 2015 among 675 previously reported children with urinary schistosomiasis in the Murbai and Surbai communities of Ardo Kola, Taraba State, Nigeria. A single dose of 40 mg/kg of praziquantel was administered to each infected child, with a second dose administered one month later if necessary. The number of eggs in urine samples was calculated at baseline and post-treatment.
RESULTS
At four weeks post-treatment, the overall cure rate was 98.1%. Among children with low and heavy parasite burdens at baseline, egg reduction rates (ERRs) were 100% and 96.5%, respectively. The vast majority of children with microhaematuria (98.7%) and proteinuria (98.6%) at baseline were cured at follow-up. Following a second dose, the ERR, overall and morbidity cure rates increased to 100%. At one year post-treatment, 272 infected children (40.3%) were re-assessed; of these, 51 children (18.8%) were reinfected. Close proximity to bodies of water (odds ratio [OR] = 1.23, 95% confidence interval [CI]: 0.998-1.530; = 0.05) and fishing (OR = 2.23, 95% CI: 0.828-6.040; = 0.01) were significant factors that predisposed children to reinfection.
CONCLUSION
A moderate rate of reinfection was noted. Governmental and nongovernmental organisations in Nigeria should collaborate on mass treatment and health education campaigns to reduce the incidence of urinary schistosomiasis reinfections.
Topics: Adolescent; Animals; Anthelmintics; Child; Child, Preschool; Female; Follow-Up Studies; Humans; Infant; Male; Nigeria; Pediatrics; Praziquantel; Prospective Studies; Schistosoma haematobium; Schistosomiasis haematobia; Treatment Outcome
PubMed: 30607270
DOI: 10.18295/squmj.2018.18.03.007 -
PLoS Neglected Tropical Diseases Apr 2024Natural interspecific hybridization between the human parasite (Schistosoma haematobium [Sh]) and bovine parasites (Schistosoma bovis [Sb], Schistosoma curassoni [Sc])...
BACKGROUND
Natural interspecific hybridization between the human parasite (Schistosoma haematobium [Sh]) and bovine parasites (Schistosoma bovis [Sb], Schistosoma curassoni [Sc]) is increasingly reported in Africa. We developed a multi-locus PCR DNA-Seq strategy that amplifies two unlinked nuclear (transITS, BF) and two linked organellar genome markers (CO1, ND5) to genotype S. haematobium eggs collected from infected people in Ile Oluji/Oke Igbo, Ondo State (an agrarian community) and Kachi, Jigawa State (a pastoral community) in Southwestern and Northern Nigeria, respectively.
PRINCIPAL FINDINGS
Out of a total of 219 urine samples collected, 57 were positive for schistosomes. All patients from Jigawa state possessed an Sh mitochondrial genome and were infected with a genetic profile consistent with an Sh x Sb hybrid based on sequences obtained at CO1, ND5, transITS and BF nuclear markers. Whereas samples collected from Ondo state were more varied. Mitonuclear discordance was observed in all 17 patients, worms possessed an Sb mitochondrial genome but one of four different genetic profiles at the nuclear markers, either admixed (heterozygous between Sh x Sc or Sh x Sb) at both markers (n = 10), Sh at BF and admixed at transITS (Sh x Sc) (n = 5), admixed (Sh x Sc) at BF and homozygous Sc at transITS (n = 1) or homozygous Sh at BF and homozygous Sc at transITS (n = 1).
SIGNIFICANCE
Previous work suggested that zoonotic transmission of S. bovis in pastoral communities, where humans and animals share a common water source, is a driving factor facilitating interspecific hybridization. However, our data showed that all samples were hybrids, with greater diversity identified in Southwestern Nigeria, a non-pastoral site. Further, one patient possessed an S. bovis mitochondrial genome but was homozygous for S. haematobium at BF and homozygous for S. curassoni at transITS supporting at least two separate backcrosses in its origin, suggesting that interspecific hybridization may be an ongoing process.
Topics: Animals; Nigeria; Humans; Hybridization, Genetic; Schistosoma haematobium; Schistosomiasis haematobia; Male; Female; Genotype; DNA, Helminth; Genome, Mitochondrial; Adult
PubMed: 38620029
DOI: 10.1371/journal.pntd.0011472 -
Parasites & Vectors May 2011Miltefosine, which is the first oral drug licensed for the treatment of leishmaniasis, was recently reported to be a promising lead compound for the synthesis of novel...
BACKGROUND
Miltefosine, which is the first oral drug licensed for the treatment of leishmaniasis, was recently reported to be a promising lead compound for the synthesis of novel antischistosomal derivatives with potent activity in vivo against different developmental stages of Schistosoma mansoni. In this paper an in vitro study was carried out to investigate whether it has a biocidal activity against the aquatic stages of Schistosoma mansoni and its snail intermediate host, Biomphalaria alexandrina , thus being also a molluscicide. Additionally, to see whether miltefosine can have a broad spectrum antischistosomal activity, a similar in vitro study was carried out on the adult stage of Schistosoma haematobium, the second major human species, its larval stages and snail intermediate host, Bulinus truncutes. This was checked by scanning electron microscopy.
RESULTS
Miltefosine proved to have in vitro ovicidal, schistolarvicidal and lethal activity on adult worms of both Schistosoma species and has considerable molluscicidal activity on their snail hosts. Scanning electron microscopy revealed several morphological changes on the different stages of the parasite and on the soft body of the snail, which further strengthens the current evidence of miltefosine's activity. This is the first report of mollusicidal activity of miltefosine and its in vitro schistosomicidal activity against S.haematobium.
CONCLUSIONS
This study highlights miltefosine not only as a potential promising lead compound for the synthesis of novel broad spectrum schistosomicidal derivatives, but also for molluscicidals.
Topics: Animals; Anthelmintics; Biomphalaria; Disinfectants; Microscopy, Electron, Scanning; Phosphorylcholine; Schistosoma haematobium; Schistosoma mansoni; Survival Analysis
PubMed: 21569375
DOI: 10.1186/1756-3305-4-73 -
PLoS Neglected Tropical Diseases Nov 2016For scientists working on gonochoric organisms, determining sex can be crucial for many biological questions and experimental studies, such as crossbreeding, but it can... (Comparative Study)
Comparative Study
For scientists working on gonochoric organisms, determining sex can be crucial for many biological questions and experimental studies, such as crossbreeding, but it can also be a challenging task, particularly when no sexual dimorphism is visible or cannot be directly observed. In metazoan parasites of the genus Schistosoma responsible for schistosomiasis, sex is genetically determined in the zygote with a female heterogametic ZW/ZZ system. Adult flukes have a pronounced sexual dimorphism, whereas the sexes of the larval stages are morphologically indistinguishable but can be distinguished uniquely by using molecular methods. Therefore, reliable methods are needed to identify the sex of larvae individuals. Here, we present an endpoint PCR-based assay using female-specific sequences identified using a genome-wide comparative analysis between males and females. This work allowed us to identify sex-markers for Schistosoma haematobium and Schistosoma bovis but also the hybrid between both species that has recently emerged in Corsica (France). Five molecular sex-markers were identified and are female-specific in S. haematobium and the hybrid parasite, whereas three of them are also female-specific in S. bovis. These molecular markers will be useful to conduct studies, such as experimental crosses on these disease-causing blood flukes, which are still largely neglected but no longer restricted to tropical areas.
Topics: Animals; Female; Genome, Helminth; Helminth Proteins; Hybridization, Genetic; Larva; Male; Schistosoma; Schistosoma haematobium
PubMed: 27861520
DOI: 10.1371/journal.pntd.0005138 -
The Journal of Parasitology Feb 1995Schistosoma mansoni and Schistosoma haematobium coexist in Egypt and in other areas in Africa, and people frequently are infected with parasites of both species. The...
Schistosoma mansoni and Schistosoma haematobium coexist in Egypt and in other areas in Africa, and people frequently are infected with parasites of both species. The effects of the interactions between worms of both sexes of the 2 species on development and egg laying were evaluated in vivo by infecting hamsters with cercariae from Biomphalaria alexandrina and Bulinus truncatus snails infected with single miracidia. In hamsters with unisex infections, male worms of both species were small. Schistosoma mansoni females were stunted and partially mature but did not contain eggs. Schistosoma haematobium females, though stunted, sometimes contained and laid small eggs, which were deposited in the liver, but few of which contained motile embryos. This suggests that unisexual infection with S. haematobium female worms produces a risk for liver damage due to egg deposition in tissues. Both S. mansoni and S. haematobium females that mated with males of the heterologous species were significantly larger than females from unisexual infections; they were sexually mature and possessed eggs in the uterus. The eggs in the liver homogenates of cross-specific infected hamsters contained fully developed miracidia that hatched in filtered pond water.
Topics: Animals; Cricetinae; Crosses, Genetic; Female; Liver; Male; Schistosoma haematobium; Schistosoma mansoni; Schistosomiasis haematobia; Schistosomiasis mansoni
PubMed: 7876983
DOI: No ID Found