U.K. scientists discover parasite protects cows against deadly East Coast fever

The tick-borne parasite that causes East Coast fever kills 1 million cows per year. Now University of Edinburgh scientists are proposing that a vaccine be made from a related--but far less deadly--parasite.

In a study of 500 indigenous East African shorthorn zebu calves, the researchers found that when animals infected with Theileria parva, which causes East Coast fever, were "co-infected" with a milder parasite such as Theileria mutans, deaths were reduced by 89%. The findings were reported recently in the journal Science Advances.

East Coast fever is a scourge in East and Central Africa, where it causes an estimated $300 million a year in losses. The only existing vaccine is made by grinding up ticks that carry T. parva--a costly process resulting in a product that itself causes an infection, which then must be treated with antibiotics.

Phil Toye, operating project leader for vaccines and diagnostics at the International Livestock Research Institute (ILRI), said in a press release that the strategy of fighting one parasite with another could be revolutionary. "East Coast fever is a major burden for millions of poor people in Africa whose existence depends on healthy cattle," Toye said. "The control methods now available are very expensive for most farmers and herders, and if we could provide a cheaper approach, it could greatly reduce poverty in the region." ILRI is leading a global effort to develop a vaccine to fight East Coast fever.

If fighting fire with fire proves effective against East Coast fever, the strategy might be applied to human parasitic diseases like malaria. Some studies suggest that infection with a mild variety of the parasite that causes malaria shields people from the deadliest form of the disease. "A better understanding of how this milder parasite may protect against the more lethal form of the disease could generate new approaches to reducing severe illness and deaths from malaria," said Mark Woolhouse, a professor at the University of Edinburgh and the lead author of the East Coast fever study, in the statement.

- here's the press release
- access the Science Advances article here