Male impotence drug Viagra makes it hard for Malaria to spread

The hugely popular erectile dysfunction medication Viagra (sildenafil citrate) has been taken by men all around the world for over 15 years to help stiffen erections for sex, and it seems this very stiffening prowess has been found to be the key element in aiding a decreased risk in the transmission of the mosquito-borne malaria parasite Plasmodium from humans to mosquitoes. In turn, this would then prevent a further passing of the virus to other people.

The findings have been laid bare in a study conducted by the London School of Hygiene and Tropical Medicine in collaboration with the CNRS, INSERM, Université Paris Descartes at the Institut Cochin and the Institut Pasteur.

How the malaria transmission can be blocked through then use of Viagra was explained by study co-author David Baker, Professor of Malaria Parasite Biology at the London School of Hygiene and Tropical Medicine.

He said: “In this new study we show that Viagra, a drug shown to be safe in humans, can make the sexual forms of the malaria parasite stiff.

“This causes them to be inactivated in the spleen and so prevents transmission of the sexual malaria parasites to mosquitoes. This is an interesting proof of concept which gives us hope that new drugs could be developed that specifically target the malaria parasite phosphodiesterase enzymes and block malaria transmission,” he added.

Plasmodium falciparum is one of the parasites that triggers the infectious, and sometimes deadly disease malaria. This parasite isn’t always easy to treat, with experts believing the single celled organism is evolving to become more resistant to the most commonly prescribed antimalarials. It is this reason why researchers continually look for other ways to fight the disease.

The parasite develops in a person’s red blood cells, which are emitted by bone marrow into the blood stream. Should a mosquito bite somebody that is already infected, it will extract some of the parasites within the blood and there is a risk that the mosquito could then infect another person by biting them.
As the blood circulates, stiff, old or abnormal blood cells are taken in by the spleen, with the healthier normal cells left to travel around. With the Viagra though, the infected red blood cells are taken in by the spleen – meaning they are not available for mosquitoes to get after biting someone. Sildenafil maintains a signalling pathway within the red blood cells, which results in the molecule cAAMP becoming more concentrated and the cells stiffening.

So far, tests have only been conducted using test tubes and there will need to be carried out with animals. If those show signs of success the next trials will need to involve humans before any medication can be approved for the use of malaria prevention.