Analysis

Dr Pieter JM Van Maaren

The Anopheles mosquito which is responsible for transmitting malaria.

As we commemorate World Malaria Day on Monday, let us not discard the fact that the mosquito-borne disease continues to threaten millions of lives around the world.

In Cambodia, malaria affects people living in poverty disproportionately, monopolising scarce resources and contributing to a cycle of poverty. Families suffer both direct health care costs and the indirect costs of lost wages, either because workers themselves become ill or because they take time from work to care for sick family members.

Malaria is transmitted by the Anopheles mosquito and is caused by a parasite that lives part of its life in mosquitoes and part in humans. Among the four Plasmodium parasite species that cause malaria in humans, Plasmodium falciparium is the most deadly. This species causes the vast majority of deaths from malaria.

Artemisinin combination therapies, or ACTs, are the most effective first-line treatments for uncomplicated falciparum malaria in malaria-endemic countries.

Recently, artemisinin-resistant falciparum malaria has emerged on the Cambodia-Thailand border. Exposure of the parasite population to artemisinin monotherapies in low or sub-therapeutic doses for more than 30 years, the availability of substandard artemisinins and fake anti-malarials have probably been the main driving force in the selection of the resistant Plasmodium falciparum parasite.

However, significant progress to bring down falciparum malaria cases has been made in Cambodia over the past two years. This is very much due to the excellent co-ordinating partnership between the Cambodian government’s National Centre for Parasitology,

Entomology and Malaria Control (CNM) and the World Health Organization, political will and the resources provided by the Bill & Melinda Gates Foundation-funded Malaria Containment Project and the Global Fund To Fight AIDS, Tuberculosis and Malaria.

The US$22.5-million multifaceted Malaria Containment Project, where WHO has joined hands with CNM in Cambodia, Thailand’s Bureau of Vector Borne Diseases, Malaria Consortium and other partners,

includes early diagnosis and appropriate treatment, active case detection through intense screening and treatment, mass distribution of long-lasting insecticide treated nets, the strengthening of management and surveillance systems and operational research.

An important component of the Containment Project is the surveillance among cross-border and mobile migrant populations as they are likely to be the source of the spread of multi-drug resistant malaria parasites due to their back and forth travel between malaria endemic areas and their place of work.

More than 2,900 lay village malaria workers have been trained to provide free malaria diagnosis to these highly mobile populations using rapid diagnostic tests and treatment with a good-quality ACT.

There are promising signs that efforts to eliminate malaria resistance along the Thai-Cambodia border are making significant gains.

In 2009, the village of Phnom Dabang in Pailin had a total of 36 falciparum malaria cases – the highest in all of the 20 most malarious villages. But in 2010, the number of cases in Phnom Dabang dropped drastically to zero due to active intervention in the intense screening and treatment. This intense screening and treatment is to quantify and contain the risk of spread of multi drug resistance falciparum malaria from the province of Pailin to other areas and to eliminate any potentially artemisinin tolerant Plasmodium falciparum detected.

The theme for this year’s World Malaria Day is “Achieving Progress and Impact”. While Cambodia has achieved progress, there is no room for complacency. The battle against killer malaria is not yet over. In the last fight to eliminate artemisinin resistance using ACTs, all Plasmodium falciparum has to be eliminated, as the last surviving parasite strains will be the most resistant ones.

Prime Minister Hun Sen made a nationwide call at the 32nd National Health Congress in March to eliminate malaria in Cambodia by 2025. WHO stands behind the government of Cambodia and supports the Ministry of Health’s 2011-2025 National Strategic Plan to Eliminate Malaria.

Towards this end, there must be continued efforts by the authorities to trace locally made or imported counterfeit anti-malarials. The Cambodian government’s efforts to ban monotherapies and crack down on counterfeit anti-malarials are certainly commendable.

In April 2010, the United States Pharmacopia – a non-governmental, official public standards setting authority for prescription and over-the-counter medicines – stated that Cambodia has shut down nearly 65 percent of illegal pharmacies.

Unlicensed drug outlets are believed to be a major source of oral artemisinin-based monotherapies, counterfeit and substandard anti-malarials and other medicines.

International co-operation and support for the country’s national law enforcement bodies are essential to stem the flow of fake artemisinin medicines and other counterfeit drugs circulating widely across and outside Southeast Asia.

There is now no group of drugs that can replace artemisinins. New, non-artemisinin-based compounds that are in the early stages of development are likely to take at least a decade until they become available for clinical use. By then it might be too late.

Cambodia and the world cannot afford to lose artemisinin and artemisinin derivatives in the treatment of malaria. WHO, the government of Cambodia and their partners will have to step up the battle against drug-resistant malaria. Hopefully this will be our last fight to eliminate the killer disease in Cambodia.

Dr Pieter JM Van Maaren is representative of the World Health Organization in Cambodia.