Journal Article

Assessing the diversity and distribution of potential intermediate hosts snails for urogenital schistosomiasis: Bulinus spp. (Gastropoda: Planorbidae) of Lake Victoria

Tumwebaze, Immaculate, Sands, Arthur F., Mahulu, Anna, Albrecht, Christian, Chibwana, Fred D.

2020

Overview

Background The Lake Victoria basin is one of the most persistent hotspots of schistosomiasis in Africa, the intestinal form of the disease being studied more often than the urogenital form. Most schistosomiasis studies have been directed to Schistosoma mansoni and their corresponding intermediate snail hosts of the genus Biomphalaria , while neglecting S. haematobium and their intermediate snail hosts of the genus Bulinus . In the present study, we used DNA sequences from part of the cytochrome c oxidase subunit 1 ( cox 1) gene and the internal transcribed spacer 2 (ITS2) region to investigate Bulinus populations obtained from a longitudinal survey in Lake Victoria and neighbouring systems during 2010–2019. Methods Sequences were obtained to (i) determine specimen identities, diversity and phylogenetic positions, (ii) reconstruct phylogeographical affinities, and (iii) determine the population structure to discuss the results and their implications for the transmission and epidemiology of urogenital schistosomiasis in Lake Victoria. Results Phylogenies, species delimitation methods (SDMs) and statistical parsimony networks revealed the presence of two main groups of Bulinus species occurring in Lake Victoria; B. truncatus / B. tropicus complex with three species ( B. truncatus , B. tropicus and Bulinus sp. 1), dominating the lake proper, and a B. africanus group, prevalent in banks and marshes. Although a total of 47 cox 1 haplotypes, were detected within and outside Lake Victoria, there was limited haplotype sharing (only Haplotype 6 was shared between populations from Lake Victoria open waters and neighbouring aquatic systems) – an indication that haplotypes are specific to habitats. Conclusions The Bulinus fauna of Lake Victoria consists of at least B. truncatus , B. tropicus , Bulinus sp. 1 ( B. trigonus ?) and B. ugandae . The occurrence and wide distribution of Bulinus species in Lake Victoria potentially implies the occurrence of urogenital schistosomiasis in communities living along the shores and on islands of the lake who depend solely on the lake for their livelihood. More in-depth studies are needed to obtain a better picture of the extent of the disease in the Lake Victoria basin.

• Publisher: BioMed Central,BioMed Central Ltd,Springer Nature B.V,BMC
• Subject: Africa / Africa - epidemiology / African lakes / Animals / Aquatic environment / basins / Biomedical and Life Sciences / Biomedicine / Biomphalaria / Bulinus / Bulinus - classification / Bulinus - genetics / Bulinus - parasitology / Correlation analysis / Cytochrome / Cytochrome c / Cytochrome oxidase / Cytochrome-c oxidase / Cytochromes / Deoxyribonucleic acid / Disease Reservoirs - parasitology / Disease Vectors / Distribution / DNA / DNA sequencing / DNA, Ribosomal Spacer - genetics / Electron Transport Complex IV - genetics / Entomology / Epidemiology / fauna / Freshwater molluscs / Gastropoda / Gene sequencing / genes / Geographical distribution / Haplotypes / Hosts / Infectious Diseases / internal transcribed spacers / Intestine / intestines / Lake basins / Lake Victoria / Lakes / Lakes - parasitology / livelihood / longitudinal studies / Marine molluscs / Marshes / Medical research / Mitochondrial DNA / Mollusks / Neglected tropical diseases / Nucleotide sequence / Parasitic diseases / Parasitology / Phylogenetics / Phylogeny / Phylogeography / Population structure / Populations / Schistosoma haematobium / Schistosoma mansoni / Schistosomiasis / schistosomiasis haematobia / Schistosomiasis haematobia - transmission / Shores / Snails / Species / Statistical methods / Surveying / Surveys / Tropical Medicine / Veterinary Medicine/Veterinary Science / Virology / Water depth