Malaria Drug Resistance in Cambodia Not a Surprise

Joe De Capua | 06 Jul 2010
Voice of America
Health officials in Cambodia have found a strain of malaria that's showing resistance to the main anti-malaria drug, known as artemisinin.

Resistance means patients can take longer to recover. Health officials and medical aid groups in Africa - home to most of the world's malaria cases - are keeping a close eye on the situation in Cambodia.

One of the groups battling the disease is Africa Fighting Malaria. Director Richard Tren says news of the drug resistance in Cambodia did not come as a surprise.

"It's not new news. This is something people have been concerned about for some time. In that part of Southeast Asia, the artemisinin-class of drugs has been used for a long time. They've been used as a mono-therapy. In other words, they haven't been combined with other drugs," he says.

Long-term use of a single drug to treat malaria leads to drug resistance, according to Tren.

"This has been the history of malaria treatment. The good part is that the authorities are trying to do something about it. This is not being ignored."

What can be done?

One of the steps being taken is improving drug treatment policies.

"They're making sure that malaria treatment is done with combination therapies so that you're mixing the artemisinin drug with a different drug that has a different mode of action. What happens then if there is resistance to the artemisinin, the other drug will take that parasite out," says Tren.

But drugs alone won't solve the malaria problem, no matter how effective. Transmission of the malaria parasite must be sharply reduced.

"If there are fewer cases of malaria, Tren says, "reduced transmission means that the resistant gene of the malaria parasite can't be drive through a population. Reducing malaria burden and improving treatment is the only way that we have to control this."

He warns though, that the situation in Cambodia is very serious because "there's no next class of drug of the artemisinin-based class of drugs. They're our last, best hope of malaria treatment and it will be many years before we get a new class of drug available."

Worse in Africa, but...

Most of the one million malaria deaths each year occur in Africa.

"The burden of malaria in Africa is much higher. There is a much more deadly strain of malaria. The falciparum malaria that you get in Africa is much more likely to kill. And unfortunately, you see the problems that you do in Southeast Asia, where you have ongoing use of these mono-therapy drugs," he says.

Africa Fighting Malaria research found a high rate of "sub-standard" and fake medicines being sold on the continent in private markets.

"We have to be clear that no drug resistance has been found in Africa yet. These artemisinin drugs are still highly effective, but it is something we have to be very vigilant about," he says.

While mono-therapy is found in Africa, official policies call for a different approach.

"Officially, all governments are supposed to be using the combination therapies. But the reality is in many African settings people buy their medicines from shops and kiosks and the mono-therapies are still being used far too much. African leaders, African governments have committed themselves to getting these mono-therapies off the market," he says.

The more mono-therapy is used in Africa, the greater the risk of artemisinin resistance.

A vaccine

A malaria vaccine would help but not solve the epidemic.

"We're closer now than ever before," Tren says, "with a good candidate vaccine that is being supported by the Gates Foundation and by the drug company GSK (GlaxoSmithKline) and other partners."

But he warns that a malaria vaccine would not be as effective as a smallpox vaccine, for example. "This will reduce the probability of dying by about half, I think. You know, this is not going to be a magic bullet,' he says.

Effective medicines and malaria control will still be needed, including insecticide treated bed nets and indoor spraying of homes with insecticides to control mosquitoes.