Monday, March 23, 2015

Using disease to fight disease

Researchers who have had success fighting an African disease hitting cattle think the solution they have found may also work as a vaccine against malaria.

The researchers from the University of Edinburgh in London, England, found that cows are protected from a parasite that causes a deadly disease called East Coast fever, if they have previously been infected with a closely-related but milder species of the parasite.

This discovery, they said, suggests that “fighting fire with fire” is a strategy that might work against a range of parasitic diseases, including severe malarial infection in people. Malaria kills about 600,000 people a year, far more than Ebola virus.

“Our results suggest seeking a simple vaccine that could protect cows from East Coast fever by inoculating them with a related but far less harmful parasite,” said Mark Woolhouse, who led the study with a team from several other universities and the International Livestock Research Institute.

“A similar process might be at work in malaria, where infection with the less harmful Plasmodium vivax parasite may protect people from the Plasmodium falciparum parasite.”

As with East Coast fever, malaria is caused by a single-celled parasite, Plasmodium, although more than one species of Plasmodium can cause the disease.

The deadliest species is Plasmodium falciparum, the most common in Africa and the cause of the vast majority of the world’s 600,000 malaria deaths a year. Plasmodium vivax is more common in Asia and more widespread but causes a less serious illness.

For their study, Woolhouse’s team tracked the health of 500 Kenyan calves from birth to one year old, building up data on the cattle’s survival, growth, health and infections with viruses, bacteria, worms and tick-borne parasites.
They found that deaths caused by East Coast fever, the biggest killer of East African cattle, dropped 89 per cent among calves which were also infected with other species of parasite that do not cause disease.