Drug-resistant malaria

"In a dusty village near the Thai-Cambodia border, 24-year-old Oeur Samoeun sits on a dark green hammock recovering from a strain of malaria that has resisted the most powerful drugs available. . . Ravaged by days of fever and chills, he is considered lucky: the parasite has left his body. But for many others, the potentially deadly disease never quite disappears."

Pailin province, where Samoeun lives, is the unwitting nursery of drug-resistant malaria. It "is the epicenter of strains of malaria that have baffled healthcare experts worldwide, raising fears a dangerous new form of malaria could already be spreading across the globe."

Last year, a study published by the New England Journal of Medicine "showed that conventional malaria-fighting treatments derived from artemisinin took almost twice as long to clear the parasites that cause the disease in patients in Pailin and others in northwestern Thailand, suggesting the drugs were losing potency in the area." USAID, a U.S. development agency, agrees that traditional arteminsinin-based therapies are "now taking two to three times longer to kill malaria parasites along the Thai-Cambodian border than elsewhere."

Three drug-resistant malaria parasites have emerged from this province over the past five decades. "Thanks to prolonged civil conflict, dense jungles and movement of mass migrants in the gem mines in the 1980s and 90s, the strains multiplied and dispersed through Myanmar, India and two eventually reached Africa."

"Few can say why it is a hotbed for drug-resistant malaria", but experts point to "a combination of sociological factors and a complicated history spanning the Khmer Rouge era when 1.7 million people, nearly a quarter of Cambodia's population, perished from execution, overwork or torture during their 1975-79 rule."

Insurgents clung to Pailin, and it was "one of their last holdouts" before their defeat in the late 1990s. During the era of the Khmer Rouge, people resided in Pailin illegally. When they contracted malaria, they bought medication through black markets and self-medicated.

Self-medication was the only way to curb the rising number of malaria cases, so Cambodia made the decision to make anti-malarial drugs available over the counter. "The strategy carried risks. Easy access reduced the number of cases but also led to incorrect dosages and substandard or counterfeit medicine". Instead of eradicating the malaria parasites, over-the-counter treatments made the parasitic population stronger against widely used medications.

Without adequate drugs to combat the disease, drug-resistant malaria parasites threaten the world. Preventative measures, such as the use of bed-nets to avoid mosquito bites, may be our best defense against malaria. Donate a bed net through Nothing But Nets.

Source:
Win, Thin Lei. Reuters. "Cambodia drug-resistant malaria stirs health fears." 6 March 2010.

Malaria in Cambodia

Researchers recently announced that a strain of malaria parasite in Cambodia has become resistant to "arteminisnin-based drugs". This development "could put millions of lives at risk" (Resistance). "Artemisinin-based combination therapies are the recommended first-line treatments of falciparum malaria in all countries with endemic disease. There are recent concerns that the efficacy of such therapies has declined on the Thai-Cambodian border, historically a site of emerging antimalarial-drug resistance" (Dondorp).

"Choloroquine and sulfadoxine-pyrimethamine resistance in P.falciparum emerged in the late 1950s and 1960s on the Thai-Cambodian border and spread across Asia and then Africa, contributing to millions of deaths from malaria. "Since the first reports of chloroquine-resistant falciparum malaria in southeast Asia and South America...drug-resistant malaria has posed a major problem in malaria control. By the late 1980s, resistance to sulfadoxine-pyrimethamine and to mefloquine was also prevalent on the Thai-Cambodian and Thai-Myanmar (Thai-Burmese) borders, rendering them established multidrug-resistant (MDR) areas" (Wongsrichanalai).

"Artemisinins have been available as monotherapies in western Cambodia for more than 30 years, in a variety of forms and doses, whereas in most countries...they have been a relatively recent introduction." An "extended period of often-suboptimal use, and the genetic background of parasites from this region, might have contributed to the emergence and subsequent spread of these new artemisinin-resistant parasites in western Cambodia." "In contrast, artemisinin derivatives have been used almost exclusively in combination with mefloquine on the Thai-Burmese border, where parasitologic responses to artemisinins remain good, even after 15 years of intensive use" (Dondorp).

The recent study compared patients from Cambodia with those from Thailand. "Researchers (Wellcome Trust-Mahidol University Oxford Tropical Medicine Research Program) discovered that on average "patients in Thailand were clear of malaria parasites within 48 hours" but Cambodian patients averaged 84 hours" (Resistance). "These markedly different parasitologic responses were not explained by differences in age" and "adverse events were mild and did not differ significantly between the two treatment groups" (Dondorp). Dr Arjen Dondorp declared, "Our study suggests that malaria parasites in Cambodia are less susceptible to artemisinin than those in Thailand". Currently, artemisinin is used to "clear the parasites at an early stage, preventing them further maturing and reproducing" (Resistance). Since its introduction, "artemisinin-based combination therapies has reduced the morbidity and mortality associated with malaria" (Dondorp).

However, with the new emergence of resistant malaria parasites, the number of malaria related deaths is expected to rise. "Measures for containment are now urgently needed to limit the spread of these parasites from western Cambodia and to prevent a major threat to current plans for eliminating malaria"(Dondorp). "Sixty percent of Cambodia's landscape poses a malarial risk. One million Cambodians are infected with malaria each year" (Wongsrichanalai). "Malaria remains one of the primary causes of mortality in Cambodia... Sustained efforts through local and national malaria control will be necessary to contain Cambodia's malaria epidemic" (Wongsrichanalai).

Image from Donorp. Graph from comparative study between Cambodia and Thailand, and how well the drugs treat malaria.


Sources:
Dondorp AM, Nosten F, Yi P, et al. Artemisinin resistance in Plasmodium falciparum malaria. N Engl J Med 2009;361:455-467.
Population Reference Bureau. "Fewer Malaria Cases in Cambodia."
"Resistance to Malaria Drug Reported in Cambodia." US World News. 29 July 2009.
Wongsrichanalai C, Pickard AL, et al. Epidemiology of drug-resistant malaria. 2002 Apr.

Advances Against Malaria | Reduction of Hospitalized Cases in Cambodia

Cambodian news sources are reporting a "50 percent drop in total malaria cases reported by public facilities between 2003 and last year, with officials crediting the success to village-based treatment" (Phnom).

"In 2008, 132,620 malaria patients were treated by village-based malaria volunteers, which has remarkably reduced the malaria death rate," according to the doctor of the National Centre for Parasitology, Entomology and Malaria Control.

Source:
LEAKHANA, KHUON AND CHRISTOPHER SHAY. The Phnom Penh Post. "Malaria cases at hospitals...". 24 June 2009.