WHO issues new malaria treatment guidelines

WASHINGTON (Reuters) - The World Health Organization asked pharmaceutical companies on Thursday to end the marketing and sale of "single-drug" artemisinin malaria medicines, in order to prevent malaria parasites from developing resistance to the drug.

The use of artemisinin monotherapy hastens development of resistance by weakening but not killing the parasite, WHO said in new malaria treatment guidelines.

"We request pharmaceutical companies to immediately stop marketing single-drug artemisinin tablets and instead market artemisinin combination therapies only," WHO Director-General Dr. Lee Jong-wook said in a statement. "It is critical that artemisinins be used correctly."

When used correctly in combination with other anti-malarial drugs in Artemisinin Combination Therapies (ACTs), artemisinin is nearly 95 percent effective in curing malaria and the parasite is highly unlikely to become drug-resistant, the United Nations health agency said.

Malaria, caused by a one-celled parasite carried by mosquitoes called plasmodium, kills at least a million people every year and makes 300 million people seriously ill. Ninety per cent of deaths are in Africa, south of the Sahara, mostly among young children, according to WHO.

According to its new treatment guidelines, falciparum malaria must be treated with ACTs and not by artemisinin alone or any other monotherapy.

The director of WHO's malaria department said no treatment failures due to artemisinin drug resistance have been documented yet, but the situation bears watching closely.

"We are concerned about decreased sensitivity to the drug in Southeast Asia, which is the region that has traditionally been the birthplace of anti-malarial drug resistance," said Dr. Arata Kochi.

In Thailand, sulfadoxine-pyrimethamine was initially almost 100 percent effective in curing malaria when introduced in 1977, but within five years was curing only 10 percent of cases due to drug resistance. The once-popular chloroquine has lost its effectiveness in almost every part of the world and resistance to atovaquone developed within one year of introduction in 1997, the statement said.

WHO urged malaria researchers and the pharmaceutical industry to quickly invest in development of the next generation of antimalarial drugs.

"Our biggest concern right now is to treat patients with safe and effective medication and to avoid the emergence of drug resistance. If we lose ACTs, we'll no longer have a cure for malaria," Kochi said, "and it will probably be at least ten years before a new one can be discovered."