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Infection with Toxoplasmosis: quantifying environmental drivers of infection

Toxoplasmosis is a globally important zoonosis with potentially devastating (and costly) health impacts for humans, domestic and wild fauna. The causative intra-cellular protozoan, Toxoplasma gondii can potentially infect all endothermic vertebrates. An estimated 350,000 people in the UK become infected with T. gondii annually: 10-20% of these experience flu-like illness, but infection is potentially severe or life-threatening in the immunosuppressed/ immunodeficient, and unborn children. Infection is also associated with major agricultural losses (e.g. as the causative agent of abortion in sheep flocks, at an estimated cost of >£10m/year in the UK). Oocyst contamination of the environment and consumption of undercooked meat are believed to be common routes of infection of humans, but the relative contribution of each is unknown in the UK, in part due to a lack of good diagnostic tools for identifying cysts.

Toxoplasma gondii has been classified into four main clonal lineages (types I, II, III and 12). Most research has focused on humans and domestic animals, but recent analyses of wild and more geographically isolated samples have identified nearly 200 distinct genotypes (Shwab et al., 2014).

Prevalence of infection with T. gondii varies spatially (e.g. Chadwick et al., 2013), potentially reflecting variation in environmental contamination with oocysts, but a detailed assessment of spatial variation in UK strain types is lacking. A spatial mismatch in strains found in humans and wildlife may allow routes of infection (environmental, v. consumption of infected meat products) to be inferred. Further to this, strain type is associated with the nature of clinical outcomes in humans. Strain typing therefore offers both a potential insight into epidemiology, and the opportunity to better target clinical care.

The current proposal aims to infer routes of human infection by comparing spatial variation in strain types found in wild infections with those in meat products and humans. Key steps in this process will include (i) prior identification of seropositive individuals (using Sabin Feldman dye testing) in order to target samples for strain typing, and (ii) development of a high resolution genetic tool for characterisation of T. gondii. Data collected as part of (i) will be used to assess abiotic/biotic drivers of prevalence, across taxa.

This is an attractive project addressing novel questions and providing diverse training opportunities in molecular ecology, spatial analysis and epidemiology, while providing data with clear applications in human and animal healthcare.

Supervisors: Dr J Lello (Cardiff), Prof M Viney (Bristol) and Dr E Chadwick (Cardiff).

For information on how to apply, click here

Start date: 1 October 2015

DEADLINE for applications is 15th Jan 2015

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