Just two cases are found in Pailin, the focus of efforts to contain the most lethal strain of the disease
Infection by the most deadly form of malaria appears to have decreased in Pailin province, where a drug-resistant strain of the disease has emerged, officials at the National Malaria Center and the World Health Organization said yesterday.
A recent mass screening of more than 1,000 people in Pailin identified just two cases of the plasmodium falciparum parasite, the severe strain of malaria that has shown drug resistance, Duong Socheat, director of the National Malaria Center said.
“The reduction is very, very remarkable…. Now there are very few cases,” Dr Socheat said.
Pailin province, on Cambodia’s western border with Thailand, is the epicenter of efforts to contain the spread of resistance to artemisinin combination therapy in the treatment of malaria, Dr Socheat said, adding that control of the disease was being achieved through insecticide spraying, rapid health intervention and increased use of mosquito bed nets.
Since 2007, resistance to ACT—the most effective drug treatment against malaria—has begun to emerge in Pailin and three other provinces: Battambang, Pursat and Kampot.
There are fears that if the malaria parasite develops resistance in Cambodia it could spread across Asia and then to Africa, where 90 percent of the million annual malaria deaths worldwide occur.
In a bid to stem the spread of the new resistant strain, a $22.4 million containment project along the Thai-Cambodian border was started by the National Malaria Center, WHO and partner organizations early last year.
The aim of the containment is to eliminate the drug resistant strain, WHO malaria specialist Steven Bjorge said yesterday.
Since last year, three strands of evidence point to a very reduced number of drug-resistant malaria cases in Pailin, Dr Bjorge said. Firstly, data from the Health Ministry; secondly, community-based Village Malaria Workers; and thirdly, results from the ongoing mass screening in Pailin, he said.
“The number of plasmodium falciparum cases have fallen off the table,” Dr Bjorge said by telephone, noting that besides the two cases found in the screening of 1,000 people, 30 cases of a less serious strain, plasmodium vivax, which has not shown resistance, were also identified.
The National Malaria Center, WHO and partner organizations continue to test all the inhabitants of 20 high-risk villages in Pailin, Dr Bjorge said.
“Plasmodium falciparum cases have almost disappeared,” he added, noting that there is 99 percent bed net coverage in the area.
Mass screenings by Medecins Sans Frontieres found plasmodium falciparum in about eight of 100 people in 2003, four of 100 in 2004 and just one in 100 in 2005, according to Kheang Soy Ty, chief of party for malaria control at University Research Co, an NGO funded by the US development agency USAID.
According to Dr Soy Ty, deforestation around Pailin was actually good for the health of the local population in terms of malaria infections, and has likely contributed to stemming the spread of the resistant strain.
“Compared to three or four years ago, malaria is drastically reduced in that area,” Mr Soy Ty said, noting that mosquitoes that spread severe malaria are found mainly in the forest, which has now been cut back.
But Cambodia is now not alone in the battle against plasmodium falciparum as reports have emerged that drug resistant strains of malaria have appeared in other areas of the region.
Last week, at a conference in Hanoi, a US official referred to the suspected emergence of drug resistant malaria in Burma, along the Sino-Burmese border and in Vietnam near the Cambodian border by Kratie province.
“First detected in western Cambodia in 2007 there are now indications of artemisinin resistance in other parts of the region,” US Global Malaria Coordinator Timothy Ziemer said during a speech on June 17, according to a copy of the address.
These cases are still under investigation and it is unknown if they developed independently or spread from the Thai-Cambodia border, Dr Bjorge said, noting the resistant strain has not yet been found in eastern Cambodia.
So far this year, a nationwide drop in malaria cases has been recorded compared to last year. From January to May public health facilities recorded 15,935 cases of malaria and 31 deaths down from 24,079 cases and 96 deaths during the same period last year, according to the National Malaria Center.