Rodents as reservoir hosts in the transmission of <i>Schistosoma mansoni</i> in Richard-Toll, Senegal, West Africa

Duplantier, Jean‐Marc; Sène, Mariama

doi:10.1017/s0022149x00000172

Cited by 54 publications

(29 citation statements)

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“…in disturbed systems elsewhere in Africa. This may be a concern if loss of native large grazers continues, because this rodent is known as not only an agricultural pest but also a carrier of intestinal schistosomiasis (Duplantier and Sene 2000) and was implicated in the origins of bubonic plague in Egypt (Panagiotakopulu 2004). In the shrinking landscapes still dominated by the full assemblage of native LMH along with traditionally managed cattle, such as in Laikipia, this and other species of small mammals persist at low densities and to a greater degree segregate into their preferred habitats, with red sands harboring the greater diversity.…”

Section: Discussionmentioning

confidence: 99%

Searching for cover: soil enrichment and herbivore exclusion, not fire, enhance African savanna small‐mammal abundance

et al. 2018

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Large mammalian herbivores (LMH) are known to suppress populations of small mammals in African savanna ecosystems; whether this suppression is driven by depletion of nutrients and food resources, or of cover, is poorly understood. Cattle management creates scattered, persistent, nutrient‐enriched areas (glades). Similarly, prescribed fire may enhance forage nutrition of burned patches. Both enriched microhabitats attract wild and domestic LMH and are fertilized by their wastes, but removal of vegetative cover by LMH or fire may negate the benefits of enhanced nutrition to risk‐averse small‐mammal species or individuals. We used replicated LMH exclusion experiments on red sandy loam and black‐cotton clay soils, and a multi‐scale burn experiment on black cotton to examine abundance, diversity, and biomass of small mammals across sites varying in vegetation cover and enrichment. Small‐mammal species composition varied dramatically among habitats. Species diversity and density on red sands were roughly double that of black cotton soils. Small‐mammal densities and diversity were dramatically greater inside LMH exclosures; maximal densities occurred inside fenced, nutrient‐rich, tall‐grass glades. Small‐mammal density was similar between black‐cotton burn sites and unburned matrix habitat but was significantly greater on unburned than burned patches within the burn sites. Burned patches contained less grassy cover up to 50 months post‐burn, although vegetation differences diminished following significant rains. Mice captured on burned patches traveled farther but were not heavier than mice captured on unburned patches. Small mammals were nearly 20‐fold more abundant on totally fenced glades than matrix habitat on both soils and ninefold more abundant on fenced bushland (non‐glades) on red sands. Unfenced glades supported intermediate densities in black cotton but lower densities in red sands because of close cropping by LMH. Total small‐mammal biomass tended to be greater on red sands (though mean body mass was greater on black cotton for two common species), within exclosures, and on glades. Both the grass rat and pouched mouse reached maximal densities within glade LMH exclosures on both soils. This and the positive association of small‐mammal densities with grass height and dead‐stem density suggest loss of cover is a primary driver of large‐herbivore suppression of certain savanna small mammals.

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Section: Discussionmentioning

confidence: 99%

Searching for cover: soil enrichment and herbivore exclusion, not fire, enhance African savanna small‐mammal abundance

et al. 2018

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“…Another possibility is that the initial pairing between these human and domestic livestock parasites occurred first in another susceptible host, such as a rodent. Rodents have proved extremely efficient for passaging a variety of schistosome species in the laboratory [17] and are utilised as reservoir hosts by other species of schistosome [51]–[54].…”

Section: Discussionmentioning

confidence: 99%

Introgressive Hybridization of Schistosoma haematobium Group Species in Senegal: Species Barrier Break Down between Ruminant and Human Schistosomes

et al. 2013

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BackgroundSchistosomes are dioecious parasitic flatworms, which live in the vasculature of their mammalian definitive hosts. They are the causative agent of schistosomiasis, a disease of considerable medical and veterinary importance in tropical and subtropical regions. Schistosomes undergo a sexual reproductive stage within their mammalian host enabling interactions between different species, which may result in hybridization if the species involved are phylogenetically close. In Senegal, three closely related species in the Schistosoma haematobium group are endemic: S. haematobium, which causes urogenital schistosomiasis in humans, and S. bovis and S. curassoni, which cause intestinal schistosomiasis in cows, sheep and goats.Methodology/Principal FindingsLarge-scale multi-loci molecular analysis of parasite samples collected from children and domestic livestock across Senegal revealed that interactions and hybridization were taking place between all three species. Evidence of hybridization between S. haematobium/S. curassoni and S. haematobium/S. bovis was commonly found in children from across Senegal, with 88% of the children surveyed in areas of suspected species overlap excreting hybrid miracidia. No S. haematobium worms or hybrids thereof were found in ruminants, although S. bovis and S. curassoni hybrid worms were found in cows. Complementary experimental mixed species infections in laboratory rodents confirmed that males and females of each species readily pair and produce viable hybrid offspring.Conclusions/SignificanceThese data provide indisputable evidence for: the high occurrence of bidirectional hybridization between these Schistosoma species; the first conclusive evidence for the natural hybridisation between S. haematobium and S. curassoni; and demonstrate that the transmission of the different species and their hybrids appears focal. Hybridization between schistosomes has been known to influence the disease epidemiology and enhance phenotypic characteristics affecting transmission, morbidity and drug sensitivity. Therefore, understanding and monitoring such inter-species interactions will be essential for optimizing and evaluating control strategies across such potential hybrid zones.

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“…Rodents are routinely used in laboratories to passage schistosome species, so they are likely to be susceptible in the wild too. However, Duplantier and Sene [31] studied 2000 animals belonging to six different rodent species collected in and around Richard Toll (Senegal) and found only S. mansoni in two rodent species ( Arvicanthis niloticus and Mastomys huberti , prevalence of about 5%). Therefore, rodents are unlikely to be involved in this hybridization event, but they might be ideal reservoirs for hybridization between S. mansoni and S. rodhaini [13].…”

Section: Discussionmentioning

confidence: 99%

Bidirectional Introgressive Hybridization between a Cattle and Human Schistosome Species

et al. 2009

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Schistosomiasis is a disease of great medical and veterinary importance in tropical and subtropical regions, caused by parasitic flatworms of the genus Schistosoma (subclass Digenea). Following major water development schemes in the 1980s, schistosomiasis has become an important parasitic disease of children living in the Senegal River Basin (SRB). During molecular parasitological surveys, nuclear and mitochondrial markers revealed unexpected natural interactions between a bovine and human Schistosoma species: S. bovis and S. haematobium, respectively. Hybrid schistosomes recovered from the urine and faeces of children and the intermediate snail hosts of both parental species, Bulinus truncatus and B. globosus, presented a nuclear ITS rRNA sequence identical to S. haematobium, while the partial mitochondrial cox1 sequence was identified as S. bovis. Molecular data suggest that the hybrids are not 1st generation and are a result of parental and/or hybrid backcrosses, indicating a stable hybrid zone. Larval stages with the reverse genetic profile were also found and are suggested to be F1 progeny. The data provide indisputable evidence for the occurrence of bidirectional introgressive hybridization between a bovine and a human Schistosoma species. Hybrid species have been found infecting B. truncatus, a snail species that is now very abundant throughout the SRB. The recent increase in urinary schistosomiasis in the villages along the SRB could therefore be a direct effect of the increased transmission through B. truncatus. Hybridization between schistosomes under laboratory conditions has been shown to result in heterosis (higher fecundity, faster maturation time, wider intermediate host spectrum), having important implications on disease prevalence, pathology and treatment. If this new hybrid exhibits the same hybrid vigour, it could develop into an emerging pathogen, necessitating further control strategies in zones where both parental species overlap.

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Rodents as reservoir hosts in the transmission of Schistosoma mansoni in Richard-Toll, Senegal, West Africa

Cited by 54 publications

References 10 publications

Searching for cover: soil enrichment and herbivore exclusion, not fire, enhance African savanna small‐mammal abundance

Searching for cover: soil enrichment and herbivore exclusion, not fire, enhance African savanna small‐mammal abundance

Introgressive Hybridization of Schistosoma haematobium Group Species in Senegal: Species Barrier Break Down between Ruminant and Human Schistosomes

Bidirectional Introgressive Hybridization between a Cattle and Human Schistosome Species

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