Epidemiology of Taenia solium Cysticercosis in western Kenya

Abstract

Taenia solium is a zoonotic helminth which is thought to be one of the leading causes of acquired epilepsy in the developing world. T. solium cysticercosis infections in pigs and humans and human taeniasis were diagnosed using antigen-capture ELISAs. The parasite was found to be endemic in the study site, with cysticercosis being detected by HP10 Ag-ELISA in 6.6% of human samples (95% C.I. 5.6-7.8%) and 17.2% (95% C.I. 10.2-26.4%) of porcine samples.

Human taeniasis was detected by Copro-Ag ELISA in 19.9% (95% C.I. 18.2-21.8%) of faecal samples. The study site was found to be co-endemic with a large selection of other neglected tropical diseases, including soil transmitted helminthiasis, schistosomiasis, strongyloidiasis and amoebiasis.

Potential control measures for this parasite have been modeled and the exclusion of infective pork from the food chain through the use of a pre-slaughter test for pig farmers, traders and slaughtermen was found to have the potential to avoid 72.6% (95% C.I. 62.1-80.9%) of infective meals consumed in the area at an incremental cost-effectiveness ratio (ICER) of $0.25 (0.2-0.35).

Such a diagnostic tool is currently under development and its performance was evaluated as part of this thesis. The novel, user-friendly lateral flow assay, utilising the HP10 monoclonal antibody, was evaluated using a Bayesian framework and was estimated to perform with a Sensitivity of 82.7% (95% B.C.I. 72.5-91.9%) and Specificity of 87% (95% B.C.I. 80.2-93.4), results which demonstrate the potential utility of this test in epidemiological studies and in control strategies.

Free-ranging pig production has been previously demonstrated to be a key risk factor for porcine cysticercosis and is commonly practised in this study region. A study carried out as part of this thesis found that these pigs have a home range of 15,085m2 which is almost 10 times the average area of a homested. This work indicates that pigs can be exposed to infective eggs from any human T. solium carriers within that homerange area, greatly assisting transmission of this parasite. Western Kenya is a severely deprived region where pig production is becoming hugely popular and is seen as a major tool for economic development, yet the data presented in this thesis indicates an area with endemic status for the harmful parasite T. solium, for which effective control strategies are desperately required.