Malaria is not the only enemy
By Roger Bate and Julian Harris, Special to The China Post
March 1, 2009, 12:27 am TWN
Malaria is deadly enough already, killing over a million people a year, but now the World Health Organization (WHO) warns it could get worse. In parts of Asia malaria is becoming increasingly resistant to even the most modern drugs—largely because of badly-made or counterfeit medicine.
This has happened before. “Resistance along the Thai-Cambodia border started with chloroquine, followed by resistance to sulfadoxine-pyrimethamine and mefloquine, drugs used in malaria control several years ago,” the WHO statement says.
A recent study in the New England Journal of Medicine demonstrates increasing resistance in Western Cambodia to the malaria “wonder drug” artemisinin (the basis of Artemisinin-based Combination Therapies, ACT). This complements studies into criminal fakes such as those by Dr Paul Newton of Oxford University. In 2006 his team surveyed artemisinin drugs throughout Cambodia, Vietnam, Laos, and Myanmar and found 68 per cent to be sub-standard.
Natural selection alone can cause diseases to mutate, but resistance is greatly exacerbated by growing numbers of counterfeit and sub-standard drugs, especially in poor countries. These often contain some correct active ingredients but not enough to cure, just enough to encourage mutation and resistance.
The fight against malaria has had some success in recent years: in 2007, there were over 75,000 malaria cases in Cambodia and Thailand combined, yet just over 300 deaths. That's an improvement on the 1990s which often saw 1,000 deaths a year in Thailand alone.
The improvement is largely due to access to new and highly effective drugs containing artemisinin—described as “a breakthrough” by the WHO. But now the miracle may be fading.
Malarial resistance to mefloquine and other drugs was overcome by artemisinin combinations but there are no new drugs to replace artemisinin. All the drugs under mid- and late-stage development are combinations using artemisinin alongside another drug. Experts meeting in Phnom Penh in January 2007 gave the newest combination only two years before a change would be required: time is up.
In the city of Pailin in Western Cambodia, near the Thai border, artemisinin efficacy has been declining. The success rate fell from 85.7 per cent in 2002 to 79.3 per cent in 2004, with similar results evident elsewhere along the Thai border. Resistance has also been noted (albeit at lower levels) in China and Vietnam.
WHO assistant director-general Hiroki Nakatani said this week that drug-resistant malaria around the Thai-Cambodian border “could spread rapidly to neighboring countries and threaten our efforts to control this deadly disease.”