The border between Thailand and Cambodia is a petri dish for drug-resistant strains of malaria. Scientists believe that in this region, more than 50 years ago, parasites that cause the disease mutated to fight a common anti-malarial drug, chloroquine, and multiplied. People carried these new parasite strains across the world, spreading the drug resistance. Today, these same borderland parasites show new signs of resistance. This time, it's to a combination of drugs, including one called artesunate, that had, until recently, made inroads against the spread of the disease. In 2004, the Cambodian government found that nearly one in five cases of artesunate sold by retailers in four provinces bordering Thailand lacked sufficient amounts of the active ingredient. Six years later, Cambodian health officials cracked down on the distribution of these counterfeits. By April 2010, officials had closed two-thirds of the country's 1,081 illegal retail shops, the main sellers of fakes.
"Closing down the illegal outlets is certainly going to have an effect on the availability of substandard drugs in the market," says Patrick Lukulay, manager of drug quality for the United States Pharmacopeia Convention (USP), which provided technical assistance to the Cambodian government. "More importantly, because there will be fewer substandard medicines ... the efficacy of the good drugs" will be improved. The hope is that these measures did not come too late.
Scientists still do not fully understand the mechanisms of drug resistance, but they do believe that drugs with inadequate levels of active ingredients encourage mutations. The same goes for medicines that were improperly made or expired. As Chris Drakeley, the director of the Malaria Centre at the London School of Hygiene and Tropical Medicine, puts it, "Suboptimal concentrations of the drug just don't kill everything."
The malaria parasite replicates so quickly that the genes left unscathed by a low dose of medicine change and multiply rapidly, creating what is essentially a new strain. But the medicine was designed for the original mutation. Drakeley says that scientists have not yet seen evidence that full-fledged resistance has developed along the Thai-Cambodian border. Still, the parasite does seem to be developing a tolerance to the drugs.
A Global Curse
An estimated 243 million people worldwide contracted malaria in 2008, according to the World Health Organization's (WHO) most recent global count. Nearly 1 million died. Eighty-five percent of the victims were children. The spread of drug resistance is one of a handful of reasons why malaria has been so difficult to contain. Cambodia's experience with fake antimalarials contains all the elements of a tragedy that's repeated across the globe. A disease that kills the poor and the weak grows until a drug is created to stop it, but the proliferation of substandard or falsified counterfeit drugs breeds a resurgence of the disease.
The range of counterfeits is vast. Authorities have seized shipments ranging from pain relievers and heart medicines to cancer drugs. Fake lifestyle drugs such as sexual stimulants and obesity treatments are commonly sold over the Internet, where governments can't stop the trade. (Though there is a system to accredit web-based drug distributors in the United States.) Wealthier nations and the wealthiest people in poor nations purchase branded drugs that are controlled and monitored by skilled regulators. But the poor in developing countries often buy cheap tablets or capsules from unregulated shops like those shut down in Cambodia. In markets, the bootleg trade still proliferates. Cambodian researchers found street sellers offering sets of four or five drugs, including artesunate, in plastic bags. "In the market, people can choose the drug that is cheapest," says Duong Socheat, director of the National Center for Parasitology Entomology and Malaria Control in Phnom Penh.
According to the WHO, it's...