Fight against tapeworm-caused epilepsy intensified

Humans are infected by the pork tapeworm, Taenia solium, by eating undercooked pork meat, containing larvae. The larva grows into a tapeworm and installs itself in your gut, where it normally causes little harm. It produces eggs that leave your body with your excrements. Where pigs have access to human faeces, as is the case in poor developing countries, the eggs produce larvae that settle in the pig, and the cycle is maintained. Problems develop when a human ingests the eggs, through contaminated water or food. In humans, these eggs grow into cysts in the tissues, including the brain, where they can cause severe neurological problems such as epilepsy.

The incidence of epilepsy has increased in sub-Saharan Africa as pig keeping and pork consumption have become more widespread in the past decade. A recent study in Tanzania shows that 14 per cent of all epilepsy may be caused by this parasite. Last year, ITM scientists found the pork tapeworm in four Congolese pigs out of ten, a worrying number.

Also last year, researchers at ITM have shown that pigs can be vaccinated against the tapeworm, so for the first time breaking the cycle. The vaccine is not yet on the market.

The ITM is one of the partners in a project of the Schistosomiasis Control Initiative (SCI), that will investigate if efforts to combat the pork tapeworm with drugs, can be integrated into existing disease prevention programmes. This program now receives a grant from the Gates Foundation.The project is coordinated by Imperial College London; the ITM researchers are responsible for the Congolese part. The WHO and other international aid workers are increasingly focussing on targeting many diseases at once. Instead of sending in a separate team for each disease, such a program treats up to seven diseases at once. Until now, diseases that jump from animals to humans did not get much attention. Yet the pork tapeworm is an evident candidate, as infected humans can be treated with praziquantel, a low-cost drug that already is part of the combination package, against the Schistosoma worm (albeit in a different dose).

In Congo, the ITM scientists will investigate if repeated administrations of high doses of praziquantel against Schistosoma, lower the number of tapeworms in humans and larvae in pigs. These numbers also will help refine the models for disease transmission in a population. The Institute of Tropical Medicine is one of the few institutions with the right expertise for combined research on humans and pigs, because it disposes of a Unit of Medical Helminthology and a Unit of Veterinary Helminthology.

The researchers not only will document the impact of integrated approaches on the burden of disease; they also will assess the cost-effectiveness of these interventions. Indeed, also the pigs profit from controlling the tapeworm in humans. To poor farmers a healthy pig is a considerable financial asset; the money in turn supports their general quality of life, including their health.