Identifying Schistosoma bovis, S. haematobium, and their hybrids among snail and human hosts in northwestern Tanzania Open Access

Abstract

Abstract   

Identifying Schistosoma bovis, S. haematobium, and their hybrids among snail and human hosts in northwestern Tanzania  

By Nidhi Muthaya   

Schistosomiasis, a major neglected tropical disease, continues to pose a significant public health concern, especially in sub-Saharan Africa. The emerging threat of hybridization between schistosome species presents additional implications for the transmission of an already complicated public health issue: research suggests that hybrids may possess the ability to establish beyond parental geographic boundaries, increased virulence, and broaden host ranges, altering schistosomiasis transmission dynamics. While hybridization in schistosomes has been extensively documented in West Africa, reporting and research in East Africa is less common, presenting a knowledge gap in African hybridization dynamics. This study selects northwestern Tanzania, an East African country, as a study site to identify Schistosoma bovis, S. haematobium, and their hybrids in snail and human hosts to understand genetic clustering and hybrid prevalence. This study also aims to examine spatial and temporal influences on genetic differentiation of selected samples to better elucidate transmission dynamics in the region. I found that S. haematobium and S. bovis were genetically distinct with hybrid prevalence of around 11% displaying potential backcrossing with the S. haematobium parental lineage. Additionally, in analyzing predictors of genetic differentiation between snail-derived samples, I found a weak but statistically significant isolation-by-distance pattern and no significant effect of sample collection time on genetic distance. These data provide additional insight into regional hybridization dynamics in northwestern Tanzania and implications for schistosomiasis transmission. This research, however, would benefit from a larger sampling effort and further analyses to full characterize hybrid prevalence and predictors of genetic differentiation for human and snail parasite samples. 

Table of Contents

Table of Contents  

Introduction……………………………………………………………………………………....1  

Methodology………………………………………………………………………………….......6  

Study design and data sources……………………………………………………………6  

Mapping and transect generation…………………………………………………………6  

FTA card sample selection……………………………………………………………......7  

Cercarial DNA extraction………………………………………………………………...7  

Rapid diagnostic PCR…………………………………………………………………….8  

Multiplex microsatellite PCR…………………………………………………………….9  

Analyses………………………………………………………………………………………….11  

Results…………………………………………………………………………………………...13  

Discussion……………………………………………………………………………………….18  

References……………………………………………………………………………………….23  

Appendix………………………………………………………………………………………...30 

About this Honors Thesis

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School	Emory College
Department	Environmental Sciences
Degree	B.S.
Submission	Honors Thesis
Language	English
Research Field	Environmental Studies Environmental Health
Keyword	Schistosomiasis
Committee Chair / Thesis Advisor	David Civitello, Emory University
Committee Members	Carolyn Keogh, Emory University Julie Clennon, Emory University

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