Filariasis

The World Health Organisation (WHO), in collaboration with other international agencies in the public and private sector, launched a global campaign last week to eliminate lymphatic filariasis by the year 2020. The disease affects 120 million people in 80 countries, and one billion people are at risk of infection in tropical regions (Bulletin of the WHO 1997;75:491-503).

In 1993 the International Task Force for Disease Eradication identified lymphatic filariasis as one of six infectious diseases that it would be possible to eliminate. It was chosen because of advances in diagnosing and treating the disease and in controlling its transmission.

The disease is caused by the parasitic filarial worms Wuchereria bancrofti and Brugia malayi. Each adult worm lives for 4-6 years in the lymphatic system, and female worms release microfilariae into the bloodstream.

Transmission occurs when a mosquito bites an infected human, picking up the microfilariae, which develop into larvae. The larvae migrate to the mosquito's mouth, and, when it bites another human, they enter the bloodstream.

The adult filariae lodge in the lymphatic system causing debilitating lymphoedema. Secondary bacterial infection can cause hardening and thickening of the skin, known as elephantiasis. In endemic communities, up to 50% of men experience genital damage, particularly hydrocele. One in 10 men and women in these communities have elephantiasis of the leg, arm, vulva, or breast.

The global eradication programme aims to break the cycle of transmission of the disease between mosquitoes and humans. Populations in endemic regions will be treated once a year for 4-6 years with a single dose of two antifilarial drugs--albendazole plus either ivermectin or diethylcarbamazine. The drugs are being donated by the pharmaceutical companies SmithKline Beecham and Merck.

Nigeria, Egypt, and Samoa will be the first three countries to benefit from the drug programme, which will start this month. Other endemic countries will be targeted later this year.

For people who already have the disease, a supplementary educational programme will teach people symptomatic treatments of proved benefit. These include limb exercises and regular washing with soap and water.

The World Bank will work with the WHO to monitor the socioeconomic impact of the eradication programme. Dr David Heymann, executive director of the Communicable Disease Cluster at the WHO, said: "Endemic countries are the poor countries of the South. There is an unequal burden of the disease, which is an obstacle to economic development."

Dr John Gyapong, deputy director of the national research unit in Ghana, welcomed the programme's launch, but warned that "the greatest difficulty will be how you get the drugs to the remotest villages and communities."

The UK government's Department for International Development is donating 3m [pounds sterling] ($4.8) towards the programme, including 1.3m [pounds sterling] to establish a lymphatic filariasis support centre at the Liverpool School of Tropical Medicine.

Details of the WHO's programme are at www.filariasis.org/index.shtml.

COPYRIGHT 2000 British Medical Association
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