Bringing DNA barcoding and landscape genetics together

A molecular taxonomy of Biomphalaria (Gastropoda: Planorbidae) in Lake Victoria and role in transmission of intestinal schistosomiasis

Background

Intestinal schistosomiasis is a common tropical disease in East Africa. The disease is associated with aquatic environments surrounding the Great East African Lakes and the parasite, Schistosoma mansoni is transmitted to man via freshwater snails of the genus Biomphalaria. Arguably the most important lake in Africa, Lake Victoria offers an unique field environment and study area for further our understanding of the epidemiology of this disease. For example, the shoreline of this lake represents one of the most disease-endemic areas of the world and yet our understanding of the roles that species of Biomphalaria play in local transmission of S. mansoni is imprecise; it is not clear why in some locations, while snails are present, the disease is largely absent and vice versa. This strongly suggests that an important evolutionary interplay of host-parasite compatibility between local snail and parasite populations is operating. With the ability of molecular DNA methods to recognize and type discrete populations of Biomphalaria as well as assay their levels of natural exposure to schistosomes, there is an exciting opportunity to build a better epidemiological picture of the natural history of intestinal schistosomiasis around Lake Victoria. The research will also have a significant impact upon current methods of disease control, linking fieldwork and laboratory studies.

Objectives
  • To provide a molecular insight into the phylogeography of Biomphalaria within Lake Victoria, establishing a robust molecular taxonomy of lakeshore populations.
  • To develop a meta-population model of the dispersal capacity of Biomphalaria spp., as inferred from population genetic parameters, testing a null-hypothesis of population panmixia across regions of the lake in Uganda, Kenya and Tanzania.
  • To test the relationship between snail population diversity and compatibility with Schistosoma mansoni – do snail populations within higher basal genetic diversity have lower field parasitaemias?
Studentship

This studentship will be an excellent period of training in molecular epidemiology and evolutionary ecology methodologies, benefiting from the support of active research groups within Biomedical Parasitology Division, NHM and the Institute of Genetics, Nottingham. The student will receive training in state-of-the-art molecular DNA methods e.g. Real-Time PCR and numerical phylogenetics. In addition, there will also be opportunities for fieldwork in Uganda, Kenya and Tanzania, seeing first-hand the applied significance of this research in control of tropical diseases.

Supervisors

Dr Russell Stothard (r.stothard@nhm.ac.uk) and Dr Chris Wade (Chris.Wade@nottingham.ac.uk).

Cartoon image of footprints leading through closing door

Our scientists study the snails that host the schistosomiasis parasite, which causes a disease that affects nearly 200 million people.