Bat 'immunity' over malaria parasites could could be key to human vaccines, says top scientist

The bugs have probably infected bats for millions of years and their immune system has evolved to cope

Bats living in the forests of West Africa harbour a surprisingly diverse range of malaria parasites which bear a close similarity to types of malaria that naturally infect wild rodents, a study has found.

About four out of ten bats tested for malaria harbour similar strains of the parasite found in forest rats. The malaria strains are different to the ones that infect humans and there is no risk of bats helping to spread malaria to people, scientists said.

Professor Susan Perkins of the American Museum of Natural History in New York said that malaria parasites have probably infected bats for millions of years and that their immune system has evolved to cope with the parasite. Knowing how they do this could be used to develop better vaccines against the disease, she added.

“The enormous diversity of malaria parasites we have found in bats shows there’s still a lot out there that has yet to be discovered and placed into a wider context,” Professor Perkins said.

“Understanding the evolution of malaria parasites in bats and other animals, and how they fit into the tree of life, is key to understanding this important human disease,” she said.

Juliane Schaer of the Max Planck Institute for Infection Biology in Berlin said: “It is unknown what the physiological effects of the parasites are on the bats, but the high diversity of parasites as well as the high proportion of individuals that are infected with the parasites suggest that this may be yet another example of the unusually high tolerance of these flying mammals for pathogens.”

Malaria is caused by a handful of species in the Plasmodium genus of single-celled parasites, which are transmitted from one animal host to another via the bite of a mosquito. About half the world’s human population is at risk of malaria, which results in about 660,000 deaths from the disease each year.

The study, published in the Proceedings of the National Academy of Sciences, involved analysing blood samples from 274 bats from 31 species, which were caught in the remote forests of Liberia, Guinea and the Cote d’Ivoire. Scientists found malaria parasites in 111 individuals, corresponding to a prevalence of about 40 per cent.

The two species of malaria parasite that the scientists identified are closely related to the group of Plasmodium parasites that infect forest rodents, suggesting some kind of transmission between the two sets of small mammals in the wild.

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