Worried over sustaining the effectiveness of malaria drug made from 'artemisinin' plant, WHO has warned pharmaceutical firms.
Lee Jong-wook, the WHO's director-general, told drug companies they must not market the drugs made from the Chinese plant artemisinin except in combination with other, older malaria drugs.
If used alone experts fear resistance would soon build up in the malaria parasite which causes the disease and the drugs would become useless.
The plant artemisinin has been used to treat malaria in China for years and the WHO urges all countries to use drugs derived from it.
"It is critical that artemisinins be used correctly," said Dr Lee. "We request pharmaceutical companies to immediately stop marketing single-drug artemisinin tablets and instead market artemisinin combination therapies (ACTs) only."
But the drug firms were given no warning and reacted with some anger to an announcement which, as far as they were concerned, came out of the blue.
"We're a bit surprised about this and we have not been involved in the process of decision making," said Herwig Jansen, president of the Belgian company Dafra. "What are we to do? Stop production and destroy our stocks? It is not the function of WHO to insist on these things. This has to be worked out together with the academic experts and the industry."
The WHO's tough line will be interpreted in some quarters as an attempt by the UN agency to re-assert its authority in the field of malaria after years of criticism for its failing Roll Back Malaria programme. Behind the new stance is the WHO's newly-appointed head of malaria, Arata Kochi. "Our biggest concern right now is to treat patients with safe and effective medication and to avoid the emergence of drug resistance," said Dr Kochi recently. "If we lose ACTs, we'll no longer have a cure for malaria and it will probably be at least 10 years before a new one can be discovered."
Drug resistance has badly damaged the fight against malaria. Sulfadoxine-pyrimethamine was initially 100 percent effective when it was introduced to Thailand in 1977. But within five years, it was effective in only 10 percent of cases. Chloroquine has lost its effectiveness throughout the world. Between 1999 and 2004 it was given to 95 percent of African children with malaria even though in many countries it cured only half of them.
As yet, there is little evidence of any problem with the artemisinin drugs. "So far, no treatment failures due to artemisinin drug resistance have been documented, but we are watching the situation very attentively," said Dr Kochi.
"We are concerned about decreased sensitivity to the drug in south-east Asia which is the region that has traditionally been the birthplace of anti-malarial drug resistance."
The companies which manufacture artemisinin single pill drugs include Sanofi-Aventis in France and Mepha in Switzerland as well as many generic manufacturers in India, China and Vietnam