Cambodia drug-resistant malaria stirs health fears

by Thin Lei Win | @thinink | Thomson Reuters Foundation
Monday, 8 March 2010 16:02 GMT

PAILIN, Cambodia (AlertNet) - 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.

His province of Pailin is the epicentre of strains of malaria that have baffled healthcare experts worldwide and raised fears they could spread across borders and beyond.

"The fear is what we're observing right now could be the starting point for something worse regionally and globally," said Dr. Charles Delacollette, Mekong Malaria Programme

Coordinator at the World Health Organisation.

A New England Journal of Medicine study last year 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.

That is echoed by U.S. development agency USAID, which says artemisinin-based combination therapy is "now taking two to three times longer to kill malaria parasites along the Thai-Cambodian border than elsewhere." The agency has helped to monitor the situation in the area for years.

The disease transmitted via mosquito bites kills more than 1 million people worldwide each year and children account for about 90 percent of the deaths in the worst affected areas of sub-Saharan Africa and parts of Asia.

The studies shine a spotlight on the remote province of Pailin, a former stronghold of ultra-communist Khmer Rouge rebels and once reknowned for blood-red rubies and lush forests.

MULTIPLIED AND DISPERSED

Pailin is the origin of three drug-resistant malaria parasites 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.

Driven from the capital, the rebels waged an insurgency from western Cambodia with Pailin one of their last holdouts until their defeat in the late 1990s.

"During the Khmer Rouge era, people came here illegally and when they get malaria, they go to the market, buy pills and self-medicate," Sophal Uth, a Pailin-based field officer for

non-profit Malaria Consortium said. "It was difficult for the government to control."

With weak public health infrastructure and rising malaria cases, Cambodia made malaria drugs available over the counter more than a decade ago. Most Cambodians don't have access to

public health services and rely on private medical centres.

The strategy carried risks. Easy access reduced the number of cases but also led to incorrect dosages and substandard or counterfeit medicine, which instead of killing the parasites only make them stronger.

MOST HAVE HAD MALARIA

For some like Oeur, artemisinin-based medicine still works.

Artemisinin, derived from the sweet wormwood, or Artemisia annua plant, is the best drug available against malaria, especially when used in artemisinin combination therapy (ACT) medicines made by firms such as Swiss drugmaker Novartis AG and France's Sanofi-Aventis.

After three days of ACT, Oeur is weak but parasite-free.

The Mekong River region of Thailand, Cambodia, Vietnam and Laos use ACTs against the "falciparum" parasite, the most severe form of malaria, as suggested by the World Health Organisation.

"Artemisinin is the most effective antimalarial we have left," Dr. Chansuda Wongsrichanalai of USAID's office of public health in Bangkok said. "We don't have any ideal alternatives

available and ready to for use in a control programme right now."

Pailin's gem mines are gone and so are most foreign migrants and the troops. Severe deforestation has left most hill tops barren. Yet the parasites are as virulent as ever. Most of its inhabitants have had malaria at least once in their lives.

Malaria experts, weary of being called alarmists, are quick to point out ACTs still work -- they are just taking longer. The WHO isn't even calling it drug-resistance, they preferred to use

the term "altered response" or "tolerance to artemisinin."

"From a public health perspective, I don't think it really matters much if it's resistance or something else given that at the end of the month, patients are returning to the health

facility with the same malaria," said Dr. John

MacArthur, chief of the President's Malaria Initiative at the U.S. Centres for Disease Control and Prevention.

Potential fallout from ACT resistance led the Bill & Melinda Gates Foundation to fund a $22.5 million containment programme. Cambodia will also receive $102 million from The Global Fund to

fight malaria in the next five years.

The Gates Foundation programme aims to use screening, bed nets and grass-roots muscle in the form of village health workers like Chan Kolap to contain the parasites along the border area and eliminate them before they can spread further.

The 42-year-old lives up the narrow dirt road from Oeur's home. Armed with a rapid diagnostic test, a thermometer and malaria pills provided by the Family Health International, Kolap treats straightforward cases of malaria in her village for free.

She refers complicated cases to the local health centre.

But the biggest challenge for the programme is reaching migrant workers like Oeur, who are on the move for months at a time. Oeur probably

caught malaria on a logging trip or while sleeping in his rickety shed without a mosquito net.

Health professionals are only too aware of what that transient lifestyle might mean for hard to treat diseases or strains of diseases.

"We live in a much more global community," MacArthur said. "The fact that a Cambodian could easily wind up in Kenya for example as tourists or labour could carry the parasites more readily now then they would have 20, 30 years ago."

Last November, Malaria Consortium said studies show artemisinin resistance already may be present in Myanmar, China and Vietnam, where between 12-31 percent of patients still had

the parasite in the system after three days of treatment.

For a Q+A on the subject, click here

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