A first alert of Biomphalaria pfeifferi in the Lower Shire, Southern Malawi, a keystone intermediate snail host for intestinal schistosomiasis

Abstract

Abstract Repeated malacological surveys were conducted in Chikwawa and Nsanje Districts in the Lower Shire River, Southern Region of Malawi to alert to and to characterize populations of Biomphalaria pfeifferi. Sampling took place across a total of 45 sites, noting water conductivity, pH, temperature, total dissolved salts (TDS) and geographical elevation. Subsequently, the presence or absence of snails was predicted upon physiochemical and environmental conditions in Random Forest modelling. A concurrent molecular phylogenetic analysis of snails was conducted alongside molecular xenomonitoring for the presence of pre-patent infection with Schistosoma mansoni. Water conductivity, TDS and geographical elevation were most important in predicting abundance of snails with water temperature and pH of slightly less important roles. Our first alert with geographical modelling of populations of B. pfeifferi in the Lower Shire River is a critical step towards improving understanding of the transmission of intestinal schistosomiasis and a more solid foundation towards developing complementary strategies to mitigate it.