The Bill & Melinda Gates foundation has been buying Viagra, in a good cause: it seems to help beat one of the common malaria parasites, Plasmodium falciparum.

The mechanism is even analogous to Viagra's better-known effect: it makes infected red blood cells stiffer, which marks them down to be cleaned out by the spleen.

As the paper notes over at PLOS Pathogens: “Blocking Plasmodium falciparum transmission to mosquitoes has been designated a strategic objective in the global agenda of malaria elimination.”

The paper explains that infected red blood cells hide in bone marrow and get released into the blood stream when the malaria gametocyte is mature.

“Release into the blood circulation is accompanied by an increase in GIE [gametocyte-infected erythrocyte – ed] deformability that allows them to pass through the spleen”, it notes.

The researchers found that the Viagra altered a particular cellular signalling mechanism, cyclic adenosine monophosphate (cAMP), which helps regulate deformability. The sildenafil drugs blocked the enzyme that makes blood cells squishy, meaning they were less likely to pass through the artificial spleen they used in the experiment.

The Bill & Melinda Gates Foundation and the Wellcome Trust part-funded the research at the Pasteur Institute in France. ®