Mitochondrial DNA analysis reveals genetic diversity and population structure of Biomphalaria alexandrina in Egypt: Implications for schistosomiasis control

Abstract

Schistosomiasis, a debilitating parasitic disease, continues to be a significant global health challenge, with Biomphalaria alexandrina serving as the primary intermediate host for Schistosoma mansoni in Egypt. This study presents an extensive mitochondrial survey and phylogenetic analysis of B. alexandrina populations sampled from eight different Egyptian governorates, utilizing mitochondrial cytochrome oxidase I (COI) and 16S ribosomal RNA (16S rRNA) gene markers. Of 279 collected specimens, 262 yielded high-quality sequences for ≥1 marker, and 248 possessed both markers and were included in concatenated analyses. We identified substantial genetic diversity within the B. alexandrina populations, with 12 distinct COI haplotypes (accession numbers: PV926494-PV926505) and 15 distinct 16S rRNA haplotypes (accession numbers: PV874566-PV874580). Bayesian phylogenetic analyses confirmed that all collected Biomphalaria individuals belonged exclusively to the B. alexandrina species, providing no molecular evidence for the presence of B. glabrata in the surveyed areas, a finding crucial for epidemiological clarity. Furthermore, population genetic analyses indicated significant population structuring and varying levels of genetic differentiation among the B. alexandrina populations, suggesting the influence of geographical barriers and historical dispersal events, including recent demographic expansion. These findings offer crucial insights into the current genetic landscape and evolutionary dynamics of B. alexandrina in Egypt, which are vital for understanding the epidemiology of schistosomiasis and for developing more targeted, effective, and sustainable snail control strategies. The study underscores the importance of continuous molecular surveillance to monitor changes in snail populations and their potential impact on disease transmission dynamics, particularly in the context of ongoing environmental changes and control efforts.