Population Genetic Structure and Hybridization of Schistosoma haematobium in Nigeria

Abstract

Background: Schistosomiasis is a major poverty-related disease caused by dioecious parasitic flatworms of the genus Schistosoma with a health impact on both humans and animals. Hybrids of human urogenital schistosome and bovine intestinal schistosome have been reported in humans in several of Nigeria’s neighboring West African countries. No empirical studies have been carried out on the genomic diversity of Schistosoma haematobium in Nigeria. Here, we present novel data on the presence and prevalence of hybrids and the population genetic structure of S. haematobium. Methods: 165 Schistosoma-positive urine samples were obtained from 12 sampling sites in Nigeria. Schistosoma haematobium eggs from each sample were hatched and each individual miracidium was picked and preserved in Whatman® FTA cards for genomic analysis. Approximately 1364 parasites were molecularly characterized by rapid diagnostic multiplex polymerase chain reaction (RD-PCR) for mitochondrial DNA gene (Cox1 mtDNA) and a subset of 1136 miracidia were genotyped using a panel of 18 microsatellite markers. Results: No significant difference was observed in the population genetic diversity (p > 0.05), though a significant difference was observed in the allelic richness of the sites except sites 7, 8, and 9 (p < 0.05). Moreover, we observed two clusters of populations: west (populations 1–4) and east (populations 7–12). Of the 1364 miracidia genotyped, 1212 (89%) showed an S. bovis Cox1 profile and 152 (11%) showed an S. haematobium cox1 profile. All parasites showed an S. bovis Cox1 profile except for some at sites 3 and 4. Schistosoma miracidia full genotyping showed 59.3% of the S. bovis ITS2 allele. Conclusions: This study provides novel insight into hybridization and population genetic structure of S. haematobium in Nigeria. Our findings suggest that S. haematobium x S. bovis hybrids are common in Nigeria. More genomic studies on both human- and animal-infecting parasites are needed to ascertain the role of animals in schistosome transmission.

Mating Interactions between Schistosoma bovis and S. mansoni and Compatibility of Their F1 Progeny with Biomphalaria glabrata and Bulinus truncatus

“…Theoretically, F1 S. mansoni × S. bovis miracidia could be evidenced in the field at least in rodent host, where both parasites' species can be found [23]. The barrier between schistosomes infecting human or animal has recently been challenged with the discovery of widespread S. haematobium × S. bovis hybrids in several West African countries [11,12,[37][38][39]. Even if S. mansoni are not closely related to S. bovis, contrary to S. haematobium they have the same tropism for the mesenteric vein system and S. mansoni × S. bovis could therefore also be evidenced in human feces.…”

MALDI-TOF: A new tool for the identification of Schistosoma cercariae and detection of hybrids

“…These latter hybrids are certainly the most worrying because they raise the eventual capability of zoonotic transmission as it evidenced in Benin previously [18,19]. Among hybrid schistosomes, S. haematobium x S. bovis hybrids received the most attention and have been identified in several West African countries including Se ´ne ´gal, Benin, Co ˆte d'Ivoire, Cameroon, Nigeria, Mali and Niger [17,[20][21][22]. These hybrids have also been responsible of an outbreak in Corsica [12], probably originating from a human migrant with autochtonous transmission by local Bulinus truncatus snails.…”

Modelling livestock test-and-treat: A novel One Health strategy to control schistosomiasis and mitigate drug resistance

“…Livestock schistosomiasis caused by S. bovis, S. curassoni and/or S. mattheei in cattle, sheep and goats is, however, prevalent across SSA (9,13). Furthermore, while human urogenital schistosomiasis was previously thought to be solely caused by the human-specific parasite S. haematobium, an ever-growing number of molecular studies have identified viable hybrids between this species and co-endemic livestock-specific parasites (9,(14)(15)(16)(17)(18)(19)(20)(21), shed in the urine of human patients of several SSA countries including Senegal (14,16,21), Niger (20), Benin (17), Malawi (15), Cote d'Ivoire (18) and Nigeria (19). Notably, S. bovis hybrids appear to be common among infected children in locations of Senegal (72% S. haematobium -S. bovis hybrid prevalence) (16) and Nigeria (89% S. bovis -S. haematobium hybrid prevalence) (19), with 'pure' S. bovis human infections recently confirmed in Cote d'Ivoire (18) and Nigeria (19).…”