Arguments en faveur d'une modification du génome (introgression) du parasite humain Schistosoma haematobium par des gènes de S. bovis, au Niger

La caractérisation de schistosomes par la morphologie des oeufs intra-utérins des vers femelles et l'analyse des phénotypes des parasites observés pour la phosphatase acide après séparation électrophorétique suggère la présence de gènes de #S. bovis, parasite du bétail domestique, chez les schistosomoses issus de l'homme dans la région est du Niger et présumés appartenir à #S. haematobium. Cette introgression naturelle pourrait également implique #S. curassoni$, un autre schistosome du bétail sympatrique des 2 autres espèces dans cette région. (Résumé d'auteur

Epidemiological Interactions between Urogenital and Intestinal Human Schistosomiasis in the Context of Praziquantel Treatment across Three West African Countries

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Interactions between Schistosoma haematobium group species and their Bulinus spp. intermediate hosts along the Niger River Valley

Background Urogenital schistosomiasis, caused by infection with Schistosoma haematobium, is endemic in Niger but complicated by the presence of Schistosoma bovis, Schistosoma curassoni and S. haematobium group hybrids along with various Bulinus snail intermediate host species. Establishing the schistosomes and snails involved in transmission aids disease surveillance whilst providing insights into snail-schistosome interactions/compatibilities and biology. Methods Infected Bulinus spp. were collected from 16 villages north and south of the Niamey region, Niger, between 2011 and 2015. From each Bulinus spp., 20–52 cercariae shed were analysed using microsatellite markers and a subset identified using the mitochondrial (mt) cox1 and nuclear ITS1 + 2 and 18S DNA regions. Infected Bulinus spp. were identified using both morphological and molecular analysis (partial mt cox1 region). Results A total of 87 infected Bulinus from 24 sites were found, 29 were molecularly confirmed as B. truncatus, three as B. forskalii and four as B. globosus. The remaining samples were morphologically identified as B. truncatus (n = 49) and B. forskalii (n = 2). The microsatellite analysis of 1124 cercariae revealed 186 cercarial multilocus genotypes (MLGs). Identical cercarial genotypes were frequently (60%) identified from the same snail (clonal populations from a single miracidia); however, several (40%) of the snails had cercariae of different genotypes (2–10 MLG’s) indicating multiple miracidial infections. Fifty-seven of the B. truncatus and all of the B. forskalii and B. globosus were shedding the Bovid schistosome S. bovis. The other B. truncatus were shedding the human schistosomes, S. haematobium (n = 6) and the S. haematobium group hybrids (n = 13). Two B. truncatus had co-infections with S. haematobium and S. haematobium group hybrids whilst no co-infections with S. bovis were observed. Conclusions This study has advanced our understanding of human and bovid schistosomiasis transmission in the Niger River Valley region. Human Schistosoma species/forms (S. haematobium and S. haematobium hybrids) were found transmitted only in five villages whereas those causing veterinary schistosomiasis (S. bovis), were found in most villages. Bulinus truncatus was most abundant, transmitting all Schistosoma species, while the less abundant B. forskalii and B. globosus, only transmitted S. bovis. Our data suggest that species-specific biological traits may exist in relation to co-infections, snail-schistosome compatibility and intramolluscan schistosome development

Infestation expérimentale de caprins par Schistosoma bovis et S. curassoni : effets pathogènes comparés

La mortalité et la morbidité spécifique dues à Schistosoma bovis et S. curassoni a été quantifiée chez des caprins élevés au Niger. L’étude a porté sur neuf animaux suivis pendant 380 jours après infestation expérimentale à l’aide de respectivement 1 800 et 2400 cercaires. S. bovis s’est révélé significativement plus pathogène que S. curassoni que ce soit en termes de mortalité, de perte de poids ou d’altération de l’hématocrite. L’intensité des symptômes cliniques s’est en outre révélée être significativement et positivement corrélée au niveau d’excrétion fécale des oeufs. Un différentiel de croissance par rapport aux témoins non infestés de respectivement 1600 et 880 grammes par mois doivent inciter à considérer S. bovis et S. curassoni comme des parasites d’importance économique dans les pays sahéliens

Infestation expérimentale de caprins par Schistosoma bovis et S. curassoni : effets pathogènes comparés

Specific mortality and morbidity have been quantified in goats experimentally infected with Schistosoma bovis or S. curassoni strains from Niger. The study involved nine animals followed during 380 days after infection with, respectively, 1,800 or 2,400 cercariae. S. bovis was significatively more pathogenic than S. curassoni in terms of mortality, weight loss and packed cell volume decrease. In addition, the intensity of clinical symptoms was significatively and positively correlated to the levels of fecal egg excretion, Compared to non-infected controls, a growth differential of, respectively, 1,600 and 880 grams per month should incite to consider S. bovis and S. curassoni as parasites of serious economical impact in sahelian countries

Infestation expérimentale de caprins par

La mortalité et la morbidité spécifique dues à Schistosoma bovis et S. curassoni a été quantifiée chez des caprins élevés au Niger. L’étude a porté sur neuf animaux suivis pendant 380 jours après infestation expérimentale à l’aide de respectivement 1 800 et 2400 cercaires. S. bovis s’est révélé significativement plus pathogène que S. curassoni que ce soit en termes de mortalité, de perte de poids ou d’altération de l’hématocrite. L’intensité des symptômes cliniques s’est en outre révélée être significativement et positivement corrélée au niveau d’excrétion fécale des oeufs. Un différentiel de croissance par rapport aux témoins non infestés de respectivement 1600 et 880 grammes par mois doivent inciter à considérer S. bovis et S. curassoni comme des parasites d’importance économique dans les pays sahéliens

Bulinus forskalii : a new potential intermediate host for Schistosoma haematobium in Niger

Malacologicat monitoring of two irrigated areas in Niger highlighted the natural susceptibility of Bulinus forskalii to infection with Schistosoma haematobium when the parasitic load is high. This first report of S. haematobium infection in B. forskalii, which is an abundant snail in irrigated areas, has been confirmed experimentally