Malaria-causing parasites unlikely to 'switch host' from animals to humans

A new research has revealed that it's very unlikely that malaria parasites that infect other animals, such as apes, birds and reptiles, would cross over easily to humans.

In recent years, public health experts have increasingly explored the idea of eliminating the most dangerous malaria-causing parasite, but they have questioned whether getting rid of this species, called Plasmodium falciparum, would allow other species of the parasite to simply jump into the gap and start infecting humans with malaria.

Researchers at the University of Maryland School of Medicine found evidence showing that five other common Plasmodium species have not changed which animals they infect for at least 3 million years.

Researcher Joana C. Silva said that according to their results, "host switching" by malaria-causing parasites is not at all a common event, on an evolutionary time scale.

Silva and her co-authors looked at hundreds of genes spread across five different species of Plasmodium and their goal was to discover how closely related the genes were, in effect, how long ago they had diverged from each other. If they had separated recently, it was more likely that they could jump from infecting one species to another.

To get their results, Silva and her colleagues developed a new statistical approach to determine when Plasmodium species split off from one another. The new method uses molecular data from thousands of genes, current techniques, by contrast, use at most sequences from dozens.

The study is published in the journal Molecular Biology and Evolution.