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In 2014, an estimated 40 million women of reproductive age were infected with and/or . In both 2003 and 2006, the World Health Organization (WHO) recommended that all schistosome-infected pregnant and breastfeeding women be offered treatment, with praziquantel, either individually or during treatment campaigns. In 2006, WHO also stated the need for randomized controlled trials to assess the safety and efficacy of such treatment. Some countries have yet to follow the recommendation on treatment and many programme managers and pregnant women in other countries remain reluctant to follow the recommended approach. Since 2006, two randomized controlled trials on the use of praziquantel during pregnancy have been conducted: one against in Uganda and the other against in the Philippines. In these trials, praziquantel treatment of pregnant women had no significant effect on birth weight, appeared safe and caused minimal side-effects that were similar to those seen in treated non-pregnant subjects. Having summarized the encouraging data, on efficacy, pharmacokinetics and safety, from these two trials and reviewed the safety data from non-interventional human studies, we recommend that all countries include pregnant women in praziquantel treatment campaigns. We identify the barriers to the treatment of pregnant women, in countries that already include such women in individual treatments and mass drug administration campaigns, and discuss ways to address these barriers.

Schistosomiasis is a neglected tropical parasitic disease associated with severe pathology, mortality and economic loss worldwide. Programs for disease control may benefit from specific and sensitive diagnostic methods to detect Schistosoma trematodes in aquatic environments. Here we report the development of novel environmental DNA (eDNA) qPCR assays for the presence of the human-infecting species Schistosoma mansoni, S. haematobium and S. japonicum. We first tested the specificity of the assays across the three species using genomic DNA preparations which showed successful amplification of target sequences with no cross amplification between the three focal species. In addition, we evaluated the specificity of the assays using synthetic DNA of multiple Schistosoma species, and demonstrated a high overall specificity; however, S. japonicum and S. haematobium assays showed cross-species amplification with very closely-related species. We next tested the effectiveness of the S. mansoni assay using eDNA samples from aquaria containing infected host gastropods, with the target species revealed as present in all infected aquaria. Finally, we evaluated the effectiveness of the S. mansoni and S. haematobium assays using eDNA samples from eight discrete natural freshwater sites in Tanzania, and demonstrated strong correspondence between infection status established using eDNA and conventional assays of parasite prevalence in host snails. Collectively, our results suggest that eDNA monitoring is able to detect schistosomes in freshwater bodies, but refinement of the field sampling, storage and assay methods are likely to optimise its performance. We anticipate that environmental DNA-based approaches will help to inform epidemiological studies and contribute to efforts to control and eliminate schistosomiasis in endemic areas.

Schistosomes cause schistosomiasis, the world’s second most important parasitic disease after malaria in terms of public health and social-economic impacts. A peculiar feature of these dioecious parasites is their ability to produce viable and fertile hybrid offspring. Originally only present in the tropics, schistosomiasis is now also endemic in southern Europe. Based on the analysis of two genetic markers the European schistosomes had previously been identified as hybrids between the livestock- and the human-infective species Schistosoma bovis and Schistosoma haematobium, respectively. Here, using PacBio long-read sequencing technology we performed genome assembly improvement and annotation of S. bovis, one of the parental species for which no satisfactory genome assembly was available. We then describe the whole genome introgression levels of the hybrid schistosomes, their morphometric parameters (eggs and adult worms) and their compatibility with two European snail strains used as vectors (Bulinus truncatus and Planorbarius metidjensis). Schistosome-snail compatibility is a key parameter for the parasites life cycle progression, and thus the capability of the parasite to establish in a given area. Our results show that this Schistosoma hybrid is strongly introgressed genetically, composed of 77% S. haematobium and 23% S. bovis origin. This genomic admixture suggests an ancient hybridization event and subsequent backcrosses with the human-specific species, S. haematobium, before its introduction in Corsica. We also show that egg morphology (commonly used as a species diagnostic) does not allow for accurate hybrid identification while genetic tests do.Author summaryIn 2013, schistosomiasis reached Southern Europe. Since then, endemic infections were recurrently identified clearly indicating that the parasite has settled and established locally. Using two molecular markers, we had previously demonstrated that the parasite was a hybrid between Schistosoma haematobium and Schistosoma bovis, two species known to infect humans and livestock, respectively. Nevertheless, this method has very low resolution and is not informative for determining the origins and the mechanisms of hybridization events, e.g. if the hybrid had been recently generated in Corsica or long before it's introduction. The genome-wide sequencing approach, used in this study, allowed us to reveal genomic admixture suggesting that these hybrids are the result of ancient crossing events between S. haematobium and S. bovis, with subsequent backcrossing with S. haematobium. This introgression has prevented compatibility with P. metidjensis snail vectors, which are specific to S. bovis. Additionally, whether in Africa or in Europe, a clear discrepancy exists between the egg shape usually used for species identification and the genomic composition of schistosomes. Therefore, egg shape cannot be used as a good indicator for hybrid detection. Knowing the phenotypic traits and the genetic features of such hybrids may have important implications in terms of diagnostics and disease management either through vector control strategies or treatment of patients.

Cercarial emission of schistosomes is a determinant in the transmission to the definitive host and constitutes a good marker to identify which definitive host is responsible for transmission, mainly in introgressive hybridization situations. Our goal was to test the hypothesis that micro-mammals play a role in Schistosoma haematobium, S. bovis, and/or S. haematobium x S. bovis transmission. Small mammal sampling was conducted in seven semi-lacustrine villages of southern Benin. Among the 62 animals trapped, 50 individuals were investigated for Schistosoma adults and eggs: 37 Rattus rattus, 3 Rattus norvegicus, 9 Mastomys natalensis, and 1 Crocidura olivieri. Schistosoma adults were found in four R. rattus and two M. natalensis, with a local prevalence reaching 80% and 50%, respectively. Two cercarial chronotypes were found from Bulinus globosus experimentally infected with miracidia extracted from naturally infected M. natalensis: a late diurnal and nocturnal chronotype, and an early diurnal, late diurnal, and nocturnal chronotype. The cytochrome C oxidase subunit I mtDNA gene of the collected schistosomes (adults, miracidia, and cercariae) belonged to the S. bovis clade. Eleven internal transcribed spacer rDNA profiles were found; four belonged to S. bovis and seven to S. haematobium x S. bovis. These molecular results together with the observed multi-peak chronotypes add M. natalensis as a new host implicated in S. haematobium x S. bovis transmission. We discuss the origin of the new chronotypes which have become more complex with the appearance of several peaks in a 24-h day. We also discuss how the new populations of offspring may optimize intra-host ecological niche, host spectrum, and transmission time period.

Schistosomiasis (bilharzia) is a neglected tropical disease caused by parasitic flatworms (blood flukes) of the genus Schistosoma , with considerable morbidity in parts of the Middle East, South America, Southeast Asia and, particularly, in sub-Saharan Africa. Infective larvae grow in an intermediate host (fresh-water snails) before penetrating the skin of the definitive human host. Mature adult worms reside in the mesenteric ( Schistosoma mansoni and Schistosoma japonicum ) or pelvic ( Schistosoma haematobium ) veins, where female worms lay eggs, which are secreted in stool or urine. Eggs trapped in the surrounding tissues and organs, such as the liver and bladder, cause inflammatory immune responses (including granulomas) that result in intestinal, hepato-splenic or urogenital disease. Diagnosis requires the detection of eggs in excreta or worm antigens in the serum, and sensitive, rapid, point-of-care tests for populations living in endemic areas are needed. The anti-schistosomal drug praziquantel is safe and efficacious against adult worms of all the six Schistosoma spp. infecting humans; however, it does not prevent reinfection and the emergence of drug resistance is a concern. Schistosomiasis elimination will require a multifaceted approach, including: treatment; snail control; information, education and communication; improved water, sanitation and hygiene; accurate diagnostics; and surveillance-response systems that are readily tailored to social-ecological settings. Schistosomiasis is a parasitic infection caused by Schistosoma spp. flatworms. Transmission of the infection occurs via contact with contaminated water, and the disease is most prevalent in areas with limited access to safe drinking water and sanitation.

This study concerns the first urinary schistosomiasis case observed in Corsica (France, Europe) occurring in a 12-year-old German boy. The aim was to identify the relationship between this Schistosoma haematobium infection and other schistosomes of the Schistosoma group with terminal-spined ova. Morphological and molecular analyses were conducted on the ova. The results showed that the schistosome responsible for the emergence of schistosomiasis in Corsica was due to S. haematobium introgressed by genes from S. bovis.

Globalization and neglected tropical diseases (NTDs) are increasingly closely linked. In recent years, Spain and Southern Europe are experiencing a considerable increase in the influx of migrants infected by NTDs, mainly from West African countries. This study focuses on imported schistosomiasis and the entry into Europe of hetero-specific hybrids between two human species, Schistosoma mansoni and S. haematobium, causing intestinal and urogenital schistosomiasis respectively. Individualized genetic identification by molecular analysis using RD-PCR, sequencing and cloning of nuclear rDNA and mtDNA of 134 Schistosoma eggs was performed, including 41 lateral-spined and 84 terminal-spined eggs from urine, and nine lateral-spined eggs from stools. These eggs were recovered from six migrant males from Senegal, Guinea-Bissau, Côte d'Ivoire and Mali, who shared ectopic shedding of S. mansoni-like eggs in their urine. A high hybridization complexity was detected in the eggs of these patients, involving three Schistosoma species. The six patients were infected by S. mansoni x S. haematobium hybrids shedding S. mansoni-like eggs, and also S. haematobium x S. curassoni hybrids shedding S. haematobium-like eggs. SmxSh hybrids were mostly detected in S. mansoni-like eggs from urine (94.59%), whereas in feces the detection of those hybrids was less frequent (5.41%). This study contributes to: (i) a better understanding of the heterospecific hybrids between S. mansoni and S. haematobium from the genetic point of view; (ii) it shows the frequency with which they are entering non-endemic countries, such as Spain and consequently in Europe; (iii) it determines the diversity of hybrid eggs and haplotypes that can occur within a single patient, e.g., up to two types of hybrids involving three Schistosoma species and up to six different haplotypes; (iv) it provides information to be considered in clinical presentations, diagnosis, responses to treatment and epidemiological impact in relation to possible transmission and establishment in non-endemic areas.

Schistosome parasites infect more than 200 million people annually, mostly in sub-Saharan Africa, where people may be co-infected with more than one species of the parasite. Infection risk for any single species is determined, in part, by the distribution of its obligate intermediate host snail. As the World Health Organization reprioritizes snail control to reduce the global burden of schistosomiasis, there is renewed importance in knowing when and where to target those efforts, which could vary by schistosome species. This study estimates factors associated with schistosomiasis risk in 16 villages located in the Senegal River Basin, a region hyperendemic for Schistosoma haematobium and S . mansoni . We first analyzed the spatial distributions of the two schistosomes’ intermediate host snails ( Bulinus spp. and Biomphalaria pfeifferi , respectively) at village water access sites. Then, we separately evaluated the relationships between human S . haematobium and S . mansoni infections and (i) the area of remotely-sensed snail habitat across spatial extents ranging from 1 to 120 m from shorelines, and (ii) water access site size and shape characteristics. We compared the influence of snail habitat across spatial extents because, while snail sampling is traditionally done near shorelines, we hypothesized that snails further from shore also contribute to infection risk. We found that, controlling for demographic variables, human risk for S . haematobium infection was positively correlated with snail habitat when snail habitat was measured over a much greater radius from shore (45 m to 120 m) than usual. S . haematobium risk was also associated with large, open water access sites. However, S . mansoni infection risk was associated with small, sheltered water access sites, and was not positively correlated with snail habitat at any spatial sampling radius. Our findings highlight the need to consider different ecological and environmental factors driving the transmission of each schistosome species in co-endemic landscapes.