From the late 1980s Cambodia’s border areas have been the battleground in a struggle to control the spread of drug-resistant malaria
By Jamie Gibbs
The sun was slowly setting on a picturesque Cambodian afternoon and as clouds gathered on the hilltops, Dr Yok Sovann, deputy director of the Pailin provincial health department, was in pensive mood. The rains had come early this year, so there would be more work coming his way.
As one of the soldiers on the frontline of the battle against malaria, his agenda is more serious than any border spat over temple ownership. Having avoided the malaria spotlight for 30 years, the Mekong is once again receiving attention from the World Health Organisation (Who), not to mention a substantial cash injection from the Bill & Melinda Gates Foundation.
In the 1950s the Cambodia/Thai border region became a breeding ground for a virulent strain of the disease. Chloroquine, the drug spearheading the fight against its spread, had become less effective as its widespread use, many experts believe, built up mosquito resistance.
Malaria also became more common because of the transient nature of the region’s workforce. As they have done for centuries, migrant workers crossed and re-crossed the border in search of more prosperous times for themselves and their families. There was no information regarding diseases or preventative measures for the workers, who often slept in hammocks strung up in the forest. After a two-week incubation period they would become infected, by which time they would be travelling somewhere else. The boom in gem mining in the region, used to fund Khmer Rouge activities, also increased the number of migrant workers and thus the number of mobile cases.
In the 1990s researchers developed artemisinin combination therapies (ACTs), a treatment derived from a Chinese herb, which was combined with a drug such as mefloquine (a successor to chloroquine). These therapies were quickly acknowledged as the most effective weapon available in the fight against malaria’s spread.
Artemisinin as a monotherapy, sub-standard counterfeit drugs and improper courses of treatment were all key causes of resistance during the days the KR controlled the area. “Sachet drugs were also a problem,” explained Dr Duong Socheat, director of Cambodia’s national malaria programme. “Each sachet may have contained a cocktail of up to five different drugs, some of which were just paracetamol or basic antibiotics.”
The possible causes of the malaria epidemic are varied, but studies are unanimous in showing that artemisinin-based therapy is no longer as effective in dealing with plasmodium falciparum, the deadliest of the four malaria parasites. While the drug used to clear the parasite from the bloodstream in 48 hours, some cases can now take up to five days.
In the health department in Pailin, the normally quiet months of April and May have seen 45 cases involving falciparum. Dr Yi Poravuth from the national centre of parasitology, entomology and malaria (CNM) believes that early rains this year will cause a glut of cases.
“We expect more cases, especially from the military where there is activity along the border,” he said. For treatment, sufferers can expect to be hospitalised for six days and although drugs are free, many still have to borrow money to pay for transport and the cost of a bed. Once there, a blood sample is taken from patients and tested every eight hours to monitor the parasite count. If it is not destroyed within 48 hours, the ACT dosage is increased and further testing and samples are sent to Phnom Penh for evaluation.
The Cambodian government has had full access to the region since 1998 and through the support of the containment programme set up by the Who has managed to suppress the surge in cases. Artemisinin is no longer administered as a monotherapy and there are few counterfeit drugs, largely due to the availability of free medication.
“One of the hardest challenges was getting the message and the drugs out to the remote villages and, subsequently, the migrant workers,” said Socheat. To tackle the problem, the programme uses a volunteer from each village trained in prescribing the correct drugs and identifying more serious cases.
Chankolab, a village volunteer in the Krong Pailin province, is proud of her work. “I have performed this role for six years,” she said, “with only two deaths – in 2004 – in my village, I am very proud. Now people come to see me with all kinds of problems.”
As well as drug administration, Chankolab maintains a village census in order to keep an eye on migrant workers who travel to the area seasonally and often in groups of 20 to 50 people. “When the workers arrive we try to find out which farm they are working for so that we can tell its owner to give out information and encourage the use of mosquito nets.”
Mosquito net distribution is another mammoth task for local authorities. Even with a substantial cash injection, only 200,000 nets have so far been delivered to a target area with a population of 2.5m. Another dilemma is persuading locals to use them for their original purpose, and not as makeshift hammocks or pillows.
Under the ever-watchful eye ofPascal Ringwald, malaria co-ordinator at the Who, more mass screenings are to take place with malarone being used instead of artemisinin. The key concern is maintaining the drug’s efficacy.
With increased collaboration between Cambodian and Thai authorities, the Who has overseen regular meetings and received assistance from the likes of The Pasteur Institute. Dr Frederic Ariey of the institute said great strides had been made in co-ordinating the southeast Asian effort with better communication and the standardisation of laboratory equipment.
According to the Who, only 3% of African children in need of ACT actually had access to it in 2006. The fear now is that by the time all African children have access to it, the drug will no longer work. The Who has acknowledged that the best hope for restricting the spread of this resistance is to eliminate the disease from the Cambodian/Thai border region and free up the drug’s use elsewhere in the world. A scenario on which Sovann is entirely focused: “I want to see the end of malaria in this country, then my work is done.”