Remarkable as it may seem, by increasing the stiffness of erythrocytes infected by the parasites that cause malaria, Viagra can result in the removal of these infected cells from blood circulation. This process could reduce the transmission of the parasite from humans to mosquitoes (and thus stop another person from becoming infected.) Viagra is a drug used to treat erectile dysfunction and pulmonary arterial hypertension.
Plasmodium falciparum is one of the parasites that triggers malaria. The parasite is difficult to treat and evidence suggests that the single celled organism is becoming increasingly resistant to common anti-malarial drugs. This is leading researchers to look for alternative means to combat the disease.
The parasite develops within red blood cells in people. These are released from the bone marrow into the blood stream. If a mosquito bites an infected person, it will take some of the parasites in with the blood and the mosquito can then potentially infect another person.
As blood circulates, the spleen takes in stiff, old or abnormal blood cells and leaves healthy cells to circulate. Researchers have found a way to stiffen infected red blood cells so that they will be taken in by the spleen and thus not be available for blood-hungry mosquitoes. This stiffening is through the drug Viagra (sildenafil citrate.) The drug can regulate a signalling pathway in the red blood cells, leading to a certain molecule — called cAAMP — to become concentrated, which leads to the cell becoming harder.
The research so far has been performed in test tubes. Further studies will be required on animals and, if these are successful, humans, before any attempt can be made with a commercial medication.
This research was carried out by scientists based at the CNRS, INSERM, Université Paris Descartes (Institut Cochin), the Institut Pasteur, and the London School of Hygiene and Tropical Medicine. The findings have been published in the journal PLOS Pathogens. The published paper is called “cAMP-Signalling Regulates Gametocyte-Infected Erythrocyte Deformability Required for Malaria Parasite Transmission.”
