Drug-resistant malaria [along Thai-Cambodian border] threatens disease control: WHO

Cambodian men, women and children receive treatment for malaria

Thursday, February 26, 2009

GENEVA (AFP) — The emergence of new drug resistant malaria at the Thai-Cambodian border could "seriously undermine" efforts to bring the disease under control, the World Health Organization said Wednesday.

"Surveillance systems and research studies... are providing new evidence that parasites resistant to artemisinin have emerged along the border between Cambodia and Thailand where workers walk for miles every day to clear forests," said the WHO in a statement.

"The risk that they may be infected with a drug-resistant form of malaria could set back recent successes to control the disease," it said.

New artemisinin-based medication has been largely credited in recent years for increasing recovery rates from the mosquito-transmitted disease that kills one million people a year.

It was regarded as a replacement for older drugs that were fast becoming useless in several areas of the world as the malaria parasite developed resistance to them.

"If we do not put a stop to the drug-resistant malaria situation that has been documented in the Thai-Cambodian border, it could spread rapidly to neighbouring countries and threaten our efforts to control this deadly disease," said WHO Assistant Director-General Hiroki Nakatani.

The WHO said it had obtained a 22.5-million-dollar grant from the Gates Foundation to find ways of containing the resistant strains of malaria.

Strains of malaria resistant to drugs such as mefloquine and sulfadoxine-pyrimethamine also emerged several years ago at the Thai-Cambodian border.

CAMBODIA: Malaria becoming deadlier

A young child sleeping under a malaria net in Cambodia (Photo: Tharum Bun/IRIN)

PAILIN, 13 January 2009 (IRIN) - A deadly strain of malaria along the Thai-Cambodian border is becoming increasingly immune to treatment, threatening the global effort to end malaria, new evidence shows.

Artemisinin combination therapy (ACT), whereby patients take both a fast-acting and slow-acting drug to kill the parasite, is losing its therapeutic effects as treatment is taking longer.

"We are facing a problem that instead of killing the parasite within 24 to 36 hours as before, ACT now needs up to 120 hours to kill the parasites," Pascal Ringwald, a medical officer at the World Health Organization (WHO), in charge of monitoring anti-malarial drug resistance, told IRIN from Geneva.

The parasite's resistance to Artemisinin, one of two drugs in ACT therapy, is the driving factor behind the deterioration of ACT.

Usually, doctors will prescribe Artemisinin with one of many slower-acting drugs.

Yet the problem is not only resistance to Artemisinin, which has existed since the 1970s, but rather tolerance to ACT, the more advanced therapy consisting of two drugs, Ringwald said. Artemisinin monotherapy refers to taking the drug alone and is not recommended by the WHO.

"Artemisinin resistance appears in parts of Southeast Asia where there has been rampant and uncontrolled use of Artemisinin monotherapy," Sir Richard Feachem, director of the Global Health Group at the University of California at San Francisco, told IRIN.

At one-tenth the price of ACT and without its adverse side-effects, such as vomiting, Artemisinin monotherapy continues to remain a popular choice for many.

However, if the threat is not contained, resistant malaria will spread through the region and hit poor communities in particular, Feachem warned.

Duong Socheat, director of the National Centre for Parasitology, Entomology and Malaria Control in Phnom Penh, told IRIN that ACTs, outreach and prevention tools like mosquito nets had seen remarkable progress despite a tolerance threat. A total of 100,000 malaria cases were reported in 2006, falling to 59,000 in 2007 and 54,000 in 2008.

The malaria death rate has been halved in only two years – from 396 in 2006 to 241 in 2007 and 184 in 2008.

Containing the threat

At an emergency meeting in October, the WHO recommended a switch to a new ACT therapy called dihydroartemisinin–piperaquine (DHA-PIP) for 2009, which is virtually 100 percent effective according to new trial results in Cambodia.

The previous ACT treatment since 2001, artesunate mefloquine, is still 90 percent effective, but unpopular among at-risk populations that still use monotherapy despite the ban.

Merchants often sell cheap, counterfeit monotherapies in rural areas.

The WHO also recommended wider distribution of mosquito nets, stricter enforcement of the ban on monotherapies, and the rapid deployment of WHO-endorsed drugs.

Drug-resistant history

Yet malaria has been developing resistance to Artemisinin for decades, and ACT tolerance is only a new phase in the parasite's evolution.

Since the 1970s, factors such as gem-mining migrants from all over Southeast Asia mixing malaria strains at the Thai-Cambodia border, an unregulated drug market, and overuse of Artemisinin monotherapy have all caused plasmodium falciparum, a common malaria parasite in Cambodia, to develop resistance to the drug.

The government and WHO responded by endorsing ACT in 2001 and banning Artemisinin-only therapy. But even ACT, despite being more than 90 percent effective against malaria, will need to be adapted soon, Feachem said.

"Ensuring that Artemisinin is always given with another drug, in the form of ACT, is a clever use of a clever drug," Feachem said. "However, parasite resistance will eventually catch up with this, and for this reason the development of new drugs ... is of the utmost importance to the health of people worldwide."

Fake drugs and patients not complying with their treatment schedules are other factors.

"If people don't take their drugs regularly, then they will have problems with resistance," Hou Nirmita, head of the health department at the Ministry of Women's Affairs, told IRIN.

But Feachem, who thinks malaria could be eradicated worldwide by 2050, sees hope. "The challenge of drug resistance, and the fact that we can never prevent the development of resistance in the long term, provides a strong argument for the acceleration of elimination and control efforts now," he said.

"To delay or to implement programmes in a half-hearted manner is both expensive and dangerous,” he explained.

According to the WHO World Malaria report for 2008, half the world's population is at risk, and an estimated 247 million cases led to nearly one million deaths in 2006. Pregnant women and children in Africa are especially threatened, the WHO says.

Thailand working to contain malaria at Cambodian-Thai border

CHANTHABURI, Aug 14 (TNA) – The Royal Thai Army is cooperating with the Department of Disease Control to prevent and contain malaria along the Cambodian-Thai border.

Chief of the Royal Thai Army Medical Department Lt-Gen. Witthaya Chowichien and Dr. Seri Hongyok, director-general of the Department of Disease Control told a press conference about the malaria prevention project along the Cambodian-Thai border on Tuesday.

The project is under the initiative of Her Royal Highness Princess Maha Chakri Sirindhorn.

Lt-Gen. Wutthipong Homwisetwongsa, head of the neighbouring countries cooperation centre said that Cambodia's Prime Minister Hun Sen asked for assistance from Thailand to prevent and contain malaria in 2005.

Gen. Sonthi Boonyaratkalin assigned the Royal Thai Army medical department to run the project following his official visit to Cambodia in January last year.

Lt-Gen. Witthaya said that the military's medical research centre has studied about Malaria along the border in the eastern province of Trat and found that the disease is more resistant to medicine. The centre is conducting the research to solve the problem.

More than 23,000 local malaria patients and 13,000 foreign patients were detected in Thailand from January through August 10. Most patients lived in 30 provinces along the borders, particularly on the Thai-Myanmar border in Tak province, followed by Thai-Malaysian border, and Thai-Cambodian border respectively, according to Dr. Seri.

Dr. Witthaya said in Chantaburi province, in the east, most patients -- 367 people were in three districts bordering Cambodia, where foreign migrants had moved to work.

However, the number of the malaria patients there decreased due to prevention measures adopted by health officials including educating local people about Malaria and suggesting them to use chemical-coated mosquito nets.

From January through July 2007, 32,044 Cambodians had their blood sample checked, with 486 found to be infected with malaria. They received medical treatment from Thai physicians.