The way malaria is transmitted controls how strongly the host's immune system reacts

Mosquito transmission of P.c. chabaudi modifies parasite gene expression in the blood stage of the cycle. [DOI: 10.1038/nature12231]

For the first time, researchers have proven that the way in which malaria is transmitted to the host affects how severe the resulting infection will be.

The route of infection modifies the malaria parasite's gene activity levels and regulates the parasite's spread in the blood by controlling the mouse's immune response. This study begins to understand how protective immunity to malaria occurs, an important step for the development of effective vaccines.

Researchers have known that the severity of symptoms of malaria increases when the malaria parasite is transferred repeatedly through blood samples in mice rather than by a mosquito, but up until now they have not known why.

"Understanding how malaria becomes more or less virulent is central to understanding how to manage and treat the disease," says Dr Matt Berriman, a senior author from the Wellcome Trust Sanger Institute. "We studied a rodent malaria species, that exhibits many of the same responses as seen in a human malaria infection. Our understanding of how the parasite interacts with the immune system is fundamentally changed by this study."

To explore the effect that the route of transmission had, the team examined the levels of gene activity in the malaria parasite during its life cycle in mice....http://www.sanger.ac.uk/about/press/2013/130529.html