Tapeworm link with epilepsy 'far higher' than thought
[GENEVA] Almost one-third of the world's epilepsy cases are caused by an avoidable food-borne parasite, according to unpublished research commissioned by the WHO.
Neurocysticercosis (NCC), an infection of the brain, has long been known to cause epilepsy and seizures, but the size of the link has surprised experts.
Common in areas with poor sanitation, NCC is the result of infection with the eggs of Taenia solium tapeworms. Eating raw or undercooked meat from pigs infected with T. solium larvae allows tapeworms to develop in the gut and shed eggs which are passed in human faeces. The eggs are ingested, either by pigs or humans, through contaminated food. They then mature into larvae which travel to the brain and cause cysts, inducing seizures.
The new review of global data by researchers at the Texas A&M University in the US is the first to investigate the global burden of epilepsy resulting from NCC infection. The researchers reviewed over 500 articles on NCC published between 1990 and 2008.
"Thirty per cent of all people suffering epilepsy in countries where tapeworm is frequent — i.e. in developing countries where pork is consumed — also suffer from NCC," said epidemiologist Christine Budke, presenting her preliminary findings to a food safety meeting in Geneva last week (29 October).
Arve Lee Willingham, deputy director of the WHO/FAO Collaborating Center for Parasitic Zoonoses, said the 30 per cent figure was "far higher than anyone had ever thought possible".
Fifty million people worldwide are affected by NCC, resulting in 50,000 deaths in developing countries. Research published in 2004 suggested 2–3 million people in Sub-Saharan Africa alone suffer from NCC-related epilepsy.
Budke insists that prevention strategies should focus on raising standards of hygiene and sanitation.
WHO medical officer, Claudia Stein, adds that pigs must be kept away from faeces and pork must be inspected before human consumption.
Willingham tells SciDev.Net that these measures are included in a six-point plan on the control and prevention of NCC in developing countries. The plan was drawn up in Laos last week by a WHO expert consultation and will be published soon.
But Willingham stresses that in the short term, epilepsy prevention will need to focus on treatment with anti-tapeworm drugs — for both infected people and pigs.
A seven-year, US$15.5 million project in Peru has successfully eradicated NCC from a test site by treating human carriers, and checking and treating pigs every two months.