A drug-resistant form of the parasite responsible for malaria is capable of infecting the species of mosquito that is the main transmitter of the disease in Africa, raising fears the hard-to-cure form of malaria could invade the world's most vulnerable continent.
Plasmodium falciparum, the deadliest malaria parasites because they are resistant to the main drugs used to treat the disease, are able to infect the Anopheles coluzzii mosquito found across Africa, a study by scientists at the U.S. National Institutes of Health found.
"The discovery suggests Africa—where malaria will cause an estimated 400,000 deaths in 2015—is more at risk for drug-resistant malaria infections than previously thought," the NIH said in a statement.
If that happens it could seriously compromise efforts to control, prevent and eliminate the disease, researchers at the institute's National Institute of Allergy and Infectious Diseases (NIAID) said.
They point out 98 percent of the global deaths from malaria in 2013 were recorded in Africa.
While cases of malaria resistant to artemisinin, the front-line treatment drug, have not yet been recorded in Africa, the worrisome variant of the disease has been spreading rapidly throughout Southeast Asia.
In laboratory experiments, researchers attempted to infect two species of Asian mosquitoes and the African Anopheles species with the drug-resistant strain of malaria.
The parasites easily infected all three species, they found.
While such transmission has not been confirmed in the wild, the experiment shows it's possible, and the parasites' ability to jump mosquito species separated by millions of years of evolution is worrying, the researchers say.
"We have parasites that are not only resistant to artemisinin ... they have no barrier to infecting multiple different mosquitoes and then transmitting the infections all the way to another human," says NIAID researcher Dr. Rick Fairhurst.
The artemisinin-resistant parasites share a genetic background that possibly allows them to infect different mosquito species by evading the insect's immune system, the researchers reported.
That's a significant concern since artemisinin has played a vital role in the fight against malaria, with malaria death rates falling 60 percent in the last 15 years.
The best way to fight the problem is at the source, says Fairhurst.
"We think this will provide additional impetus for intensifying—and by intensifying, I mean grossly intensifying—the malaria elimination efforts in Southeast Asia," he says.
The drug-resistant Plasmodium falciparum was first detected in Cambodia in 2008 but has since been detected throughout the region, researchers say.
