Science & Environment

Drug-resistant malaria can infect African mosquitoes

Malaria Parasite Image copyright Science Photo Library
Image caption Drug-resistant forms of the malaria parasite have been found in South East Asia

A drug-resistant malaria parasite found in South East Asia can also infect mosquito species in Africa, a study shows.

The transmission experiments were carried out in a laboratory, but they suggest the spread of this deadly strain into the continent is possible.

The scientists say the consequences of this would be dire, putting millions of lives at risk.

The study is published in the journal Nature Communications.

Dr Rick Fairhurst, from the National Institute of Allergy and Infectious Disease (NIAID), in the US, who carried out the research, said: "We think this will provide additional impetus for intensifying - and by intensifying, I mean grossly intensifying - the malaria elimination efforts in South East Asia."

Jumping species

This drug-resistant parasite was first seen in Cambodia in 2008, but has since been reported across South East Asia.

It is rendering the best front-line drug - Artemisinin - useless.

But this is not the first time this has happened. Since the 1950s, drug after drug has stopped working as the malaria parasite (Plasmodium falciparum) has evolved. And each time, the problem has first emerged on the Thai-Cambodia border before spreading around the world.

Scientists now fear that the Artemisinin-resistant parasite also has this potential to disperse, but until now, very little has been known about its transmission.

"All of us are very concerned about these parasites spreading to Africa, as parasites did in the past, but there was no reason to think these very highly differentiated parasites could even infect the major vector in Africa," said Dr Fairhurst.

Image copyright Science Photo Library
Image caption Lab experiments revealed that the parasite can infect Africa's main malaria-carrying mosquito

To investigate, the researchers carried out laboratory experiments, infecting two species of Asian mosquitoes and Africa's main malaria-carrying mosquito - Anopholes coluzzii (formerly called A. gambiae M) - with the drug-resistant strain.

"We were quite amazed that not only was (A, coluzzii) readily infected, it also didn't really seem to be less infected that the two native South East Asian vectors," said Dr Fairhurst.

"It was quite surprising to us - we thought maybe we'd see at least some reduction."

The researchers say the parasite's ability to jump species that are separated by millions years of evolution is concerning.

And while such transmission has not been seen yet in the wild, this study shows that it is possible.

Dr Fairhurst said: "This is just one more piece to the puzzle that looks like a worldwide catastrophe.

"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."

He added: "We think that these parasites are going to be extremely difficult to stop the spread of, and that just can't be good for ay kind of containment effort."

Artemisinin has played a key role in the fight against malaria.

The World Health Organization estimates that in the last 15 years malaria death rates fell by 60% globally and 6.2 million malaria deaths have been averted.

Scientists warn that they cannot afford to lose this drug.

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