摘要
Background:Hybrids between Schistosoma haematobium(Sh)and S.bovis(Sb)have been found in several African countries as well as in Europe.Since the consequences of this hybridization are still unknown,this study aims to verify the presence of such hybrids in Cameroonian humans,to describe the structure of S.haematobium populations on a large geographic scale,and to examine the impact of these hybrids on genetic diversity and structure of these populations.Methods:From January to April 2019,urine from infected children was collected in ten geographically distinct popu‑lations.Miracidia were collected from eggs in this urine.To detect the presence of hybrids among these miracidia we genotyped both Cox1(RD-PCR)and ITS2 gene(PCR-RFLP).Population genetic diversity and structure was assessed by genotyping each miracidium with a panel of 14 microsatellite markers.Gene diversity was measured using both heterozygosity and allelic richness indexes,and genetic structure was analyzed using paired Fst,PCA and Bayesian approaches.Results:Of the 1327 miracidia studied,88.7% were identifed as pure genotypes of S.haematobium(Sh_Sh/Sh)while the remaining 11.3% were hybrids(7.0% with Sh_Sh/Sb,3.7% with Sb_Sb/Sh and 0.4% with Sb_Sh/Sb).No miracidium has been identifed as a pure genotype of S.bovis.Allelic richness ranged from 5.55(Loum population)to 7.73(MattaBarrage)and difered signifcantly between populations.Mean heterozygosity ranged from 53.7%(Loum)to 59%(Matta Barrage)with no signifcant diference.The overall genetic diferentiation inferred either by a principal compo‑nent analysis or by the Bayesian approach shows a partial structure.Southern populations(Loum and Matta Bar‑rage)were clearly separated from other localities but genetic diferentiation between northern localities was limited,certainly due to the geographic proximity between these sites.Conclusions:Hybrids between S.haematobium and S.bovis were identifed in 11.3% of miracidia that hatched from eggs present in the urine of Cameroonian schoolchildren.The percentages of these hybrids are correlated with the genetic diversity of the parasite,indicating that hybridization increases genetic diversity in our sampling sites.Hybridi‑zation is therefore a major biological process that shapes the genetic diversity of S.haematobium.
