Tapeworm research moves closer to wiping out lethal brain disease

Media Release, Monday 13 March 2006

New research has moved University of Melbourne scientists a step closer to eradicating a parasite that infects 50 million people annually and causes a lethal brain disease that kills 50,000 in the developing world each year.

The scientists, from the University’s Faculty of Veterinary Science, in Werribee, have developed a vaccine to immunise pigs against the parasite Taenia solium, which causes tapeworm infestations in 50 million people each year.

Tapeworms can grow many metres long in humans with no health implications, but the eggs laid by tapeworms – which are transmitted only in human faeces - cause the often fatal brain disease, neurocysticercosis.

Vaccine project leader Associate Professor Marshall Lightowlers said a major challenge in fighting parasitic diseases was that many parasites varied genetically in different countries or regions, making it difficult to develop a single vaccine.

But new experimental results, published by Associate Professor Lightowlers and colleague Charles Gauci in this month’s Journal of Molecular and Biochemical Parasitology, shows there is little variation in the Taenia solium parasite across 10 different countries in Asia, Africa and Central America.

“Now we know the parasite doesn’t change, we have overcome a major hurdle,’’ Dr Lightowlers said. “It is likely that we can use this vaccine on pigs anywhere in the world.’’

The University of Melbourne team developed the vaccine by isolating the genes of proteins taken from tapeworm eggs and then growing those genes in bacteria to generate a pure vaccine protein.

Dr Lightowlers said previous field trials of the vaccine in Mexico, Peru, Cameroon and Honduras showed the pigs vaccinated had a 99.5 per cent immunity against the Taenia solium parasite.

According to the World Health Organisation, neurocysticercosis is the leading cause of epilepsy in many countries in the developing world.

It is an extremely serious health problem in the Asia, Africa and South America. Those infested with the parasite form cysts in the brain which can cause paralysis and death.

In countries without proper sanitation, and where pigs and humans live in close quarters, there is a constant cycle of re-infection.

Pigs contract the tapeworm parasite from contact with human faeces, it is then passed on to humans who eat improperly cooked pig meat, and then more seriously, from human to human via exposure to tapeworm eggs in human faeces.

Dr Lightowlers said researchers had decided to develop the vaccine to protect pigs against Taenia solium rather than humans as it was easier and more cost effective.
The Faculty of Veterinary Science has received a five-year, $1.8 million grant from the Wellcome Trust UK to further develop the vaccine and conduct field trials until 2009.

Dr Lightowlers said the group was aiming to conduct a trial in an isolated location such as an island – vaccinating pigs against the disease and treating all humans in the area for tapeworm.

“Our ultimate goal is complete eradication of the disease,’’ Dr Lightowlers said.

MEDIA CONTACT

Marshall Lightowlers
03 9731 2284
0419 939 780