Birds are the main host for the West Nile virus, which is transmitted to humans by mosquitoes
An especially drug-resistant type of malaria is becoming dominant in parts of the Mekong region, researchers said Thursday, warning of potentially dire consequences if it makes the leap to India and Africa.
For the last decade scientists and health workers have become increasingly alarmed by the spread of a malaria strain resistant to a key drug used to treat patients: artemisinin.
It was first detected in western Cambodia in 2007 and has since spread to parts of northeastern Thailand, southern Laos and eastern Myanmar.
Now researchers have also discovered a version of that strain that is not only resistant to two types of drugs, but has muscled out its less dangerous peers to become the dominant variant, according to a paper published Thursday in The Lancet Infectious Diseases medical journal.
"What's happened now is that one lineage which arose in western Cambodia, one family of parasites if you like, has effectively beaten all the rest out and has spread," Nicholas White, a specialist from the Mahidol Oxford Tropical Medicine Research Unit (MORU) in Bangkok, which led the research, told AFP.
So far the dominant lineage has been detected in parts of Cambodia, Thailand and Laos but not Myanmar -- the bridge to South Asia -- although researchers believe it us just a matter of time before it pushes westwards.
For tropical disease experts, the emergence of this strain has a worrying historical precedent.
Last century the borderlands of Cambodia, Thailand and Laos incubated two previous waves of drug-resistant malaria that spread from the region to India and Africa where they killed millions.
The first was a chloroquine resistant strain that emerged in the 1950s and 1960s and the second wave was a type of parasite impervious to the next generation of anti-malarial medicine, sulphadoxine pyrimethamine (SP).
The Chinese military came to the rescue when a female chemist discovered artemisinin in the 1970s during a secret project to protect their North Vietnamese allies from the debilitating disease in their war against the United States.
- Clock is ticking -
The discovery, coupled with worldwide preventative measures against the mosquitoes, resulted in significant successes made against malaria over the last few decades.
But scientists fear much of those gains could unravel if the latest generation of drug-resistant parasites is not tackled.
"There's been too much talking and not enough doing on this," warned White.
Arjen Dondorp, the study's lead author, told AFP a major global effort was needed to stop the latest generation of drug resistant malaria before it heads west.
"Once it is in Africa that would be a disaster because that is where most of the world's malaria cases are," he said.
Doctors are hampered by the lack of arteminisin-like breakthroughs.
Some new drugs are being worked on with "several compounds" that look promising, Dondorp said, but the testing takes time.
Meanwhile a triple cocktail of drugs is currently working against the latest malaria strain, though resistance to that could build.
In the meantime, he said, Cambodia, Thailand, Laos and Myanmar have to aggressively target the often remote, poor and inaccessible regions where the strains are emerging with "creative use of drugs".
Significant money has been made available from international donors and funds, he said.
"But the window of opportunity is getting shorter and shorter."
His colleague White added, "Today we don't have untreatable malaria, we have malaria that is becoming increasingly more difficult to treat. But the prospects for the next few years are very uncertain."