Sept. 18 (UPI) -- Researchers have found six compounds that could prevent mosquitoes from being infected with malaria parasites as a way to stop the spread of the disease to humans.
Around 70,000 compounds were studied by researchers at Imperial College London, who published their findings Tuesday in the journal Nature Communications.
They settled on ones that can be turned into drugs that block disease transmission from the never-ending cycle of an infected mosquito infecting a person, whose parasites mix with another mosquito's saliva and are injected into another person through a bug bite.
Malaria is not spread from person to person.
"It took several years to find the right conditions that would stimulate the sexual parasites and to miniaturize the environment, but it was worth it -- at our best we were screening 14,000 compounds a week!," lead researcher Dr. Jake Baum, from the Department of Life Sciences at Imperial, said in a press release. "Overall we screened around 70,000 molecules and found only a handful of potent compounds that are both active and safe to use with human cells. It was like finding needles in a haystack."
Drugs can wipe out the parasites in people, but they still carry dormant, sexual forms, which then transfer the parasite to another mosquito. They rapidly mature and multiply -- ready to feast on a new person bit by the mosquito.
"Current antimalarial drugs can cure a person of the disease, but that person is still infectious to mosquitoes, and can therefore still cause someone else to become infected," Baum said. "What we propose is antimalarial drugs that protect mosquitoes, blocking the parasites from continuing their infectious journey. By combining such a drug with a conventional antimalarial, we not only cure the individual person, but protect the community as well."
One probem is parasites become resistant to antimalarial drugs.
"Since transmission occurs in the mosquito, drugs targeting this process have the added benefit of being naturally much more resistance-proof, which could be essential for eliminating malaria," Baum said.
One compound has been identified that blocks parasite transmission from mice, but researchers are researching all the identified compounds further.
Because drugs could not be given directly to mosquitoes, they would need to be stable enough to be given to a human and survive a transfer into the mosquito.
And because the parasites are dormant and not very reactive, they are very difficult to attack with conventional drugs. Male and female forms after sex in the mosquito create more newly infectious asexual parasites.
Because the sexual parasites are very active, they are one of the fastest replicating cell types known and make them surprisingly good drug targets. They key is fooling parasites into starting sexual development.
After finding the right conditions, they miniaturized the process to examine them with a microscope. And the process of screening 68,689 compounds from the Global Health Chemical Diversity Library was underway.