The malaria parasite, carried by mosquitoes, is growing resistant to artemisinin-based drugs.James Gathany / CDCPosted on 07/29/2009 9:40:12 PM PDT by neverdem
Artemisinin-based medicines fail a growing number of patients in Cambodia.
The malaria parasite, carried by mosquitoes, is growing resistant to artemisinin-based drugs.James Gathany / CDCMalaria parasites in Cambodia are becoming increasingly resistant to the drug hailed as the world's best chance to eradicate the disease.
Artemisinin-based drugs are currently the best weapon against malaria, a disease which kills around a million people every year and is spread by mosquitoes carrying malaria parasites such as Plasmodium falciparum. These parasites have already developed resistance to drugs such as chloroquine and sulfadoxine-pyrimethamine, once the front line against the disease, so hopes have been pinned on artemisinin-combination therapies (ACTs).
The parasites have become far less easy to treat with ACTs, however, in the Cambodian city of Pailin, close to the country's western border with Thailand. The finding was made by researchers from the Wellcome Trust–Mahidol University Oxford Tropical Medicine Research Programme, based in Bangkok, Thailand.
In particular, the parasites are becoming more resistant to a combined therapy of artesunate, derived from artemisinin, and mefloquine, a quinine analogue. This combination is used to treat malaria worldwide.
Rumours about artemisinin resistance in Cambodia have been circulating for a number of years, and a relatively small study by Harald Noedl at the Medical University of Vienna and his colleagues, published late last year, suggested that resistance was emerging1.
The latest study involved 40 patients infected with P. falciparum in Pailin, and another 40 in Wang Pha, in northwest Thailand2. Half of each group were given just artesunate, and the other half the dual artesunate–mefloquine therapy.
“This is a wake-up call”
Nick Day
Mahidol Oxford research unit, Bangkok
The Cambodian group took almost twice as long to clear the parasite from their body as the Thai group: 84 hours compared with 48 hours. Usually artemisinin drugs clear the parasite within three days, says Nick Day, director of the Mahidol Oxford research unit in Bangkok and co-author of the study, published in the New England Journal of Medicine.
Infection broke out again for six of the twenty patients taking just artesunate in Cambodia, compared with two patients in Thailand. With the combined therapy, it recurred in only one of the twenty cases in each group.
The World Health Organization recommends that artemisinin-based drugs be given only in combination, to delay the onset of resistance. But Day explains that the single-dose groups were crucial in their controlled study to show that there was growing resistance to artesunate, and not to mefloquine alone.
The emergence of artemisinin-resistant malaria in Cambodia is especially worrying, because previous drug-resistant strains of malaria have sprung from there. "This is a wake-up call," says Day. "We have got reduced susceptibility to the drugs in an area where we've seen resistance emerge before." Given time, the parasite will only become more resistant to the drugs, he adds.
The research offers a clear warning that efforts to eradicate malaria should be accelerated, says Sanjeev Krishna from St George's University of London, who studies the biochemical origins of artemisinin resistance. He says that he expected resistance to occur eventually — but not as soon as this. "I thought we would have had longer," he says. More intensive drug-development programmes are needed, he adds, to find new drugs based on artemisinin, as well as alternatives.
An eradication programme combining continued treatment and use of mosquito nets is under way in this area of Cambodia, Day says. "It's going to need considerable political willpower, scientific research and financial resources to achieve," he cautions. But without it, there is a danger that the resistant parasite could reach the world's malaria heartland — Africa. "That," says Day, "would be a major disaster."
Evidence of Artemisinin-Resistant Malaria in Western Cambodia
Bring back DDT.
Micro ping - is malaria a problem in veterinary medicine Doug?
And methylene blue...
yitbos
“Bring back DDT.”
I am not sure where I read it, (I believe it was National Geographic) but I recall reading an article that stated the ban on DDT was responsible for thousands of deaths in sub-Saharan Africa each year. Nobody likes using noxious chemicals - but a lot of times it is the best alternative we have.-—JM
Exactly. Cheap, safe and effective, and would save far more lives than these stupid send a mosquito net to a third world victim of UN stupidity campaigns these idiotic activist teachers keep brainwashing kindergarten and first grade children with.
Artemisinin. Derived from wormwood. Touchy stuff, can be highly toxic. Touted as being effective for certain cancers, too.
I learned a lot, trying to help my best buddy, a Chocolate Lab. He had cancer. Lived well past the best-case six month prognosis. Tried a lot of things, but never got around to artemisinin. I was scared of it.
Mosquito resistance to DDT:
I don't put much faith in enviro wacko non-science. And they've had years and millions of bodies to de-contstruct the history of the values of DDT.
yitbos
I ain't dead.
yitbos
Rachel Carson may have been proved a liar, but there is now a ton of evidence of DDT resistance in insects. DDT is still a huge help but it isn't a panacea.
What’s an insect generation, a few months at the most? That gives plenty of time for the gene mutation that allows resistance to the pesticide to become a trait of the insect.
Yes.
Team finds key mechanism of DDT resistance in malarial mosquitoes
I have only been covered with pesticide once, a long time ago when I was thinning apples in eastern Washington State. A crop duster covered everyone working in the orchard with white powder. Jerk. I wasn't too happy about it, but I didn't get sick.
yitbos
Including Meryl Streep.
Maybe that stuff was alar.
I'd have to do a literature review to identify the animals that are suseptible to the Plasmodium spp. I do know that in the late 1960's and early 1970's the USAF tested the efficacy of several drugs ability to treat malaria using primates as the animal models. Several techs I worked with had been involved with the experiments. I think they primarily tested P. falciparum infected primates. With respect to public health, I'd bet many MPH veterinarians are dealing with the epidemiology of the malaria epidemic.
Thank you.
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