Neglected tropical diseases

Lymphatic filariasis (elephantiasis): 546 million people treated worldwide in 2007 alone

22 Sept. 08 | Geneva

In 2007,** 546 million people around the world were treated to prevent transmission of lymphatic filariasis (LF), commonly known as elephantiasis. The numbers reached in 2007 make the Global Programme to Eliminate Lymphatic Filariasis the largest public health programme using mass drug administration (MDA) to prevent a tropical disease.

A total of 81 countries are endemic for the disease. In 2007, treatment was delivered at an increased rate in 48 countries, 27 of which are implementing disability prevention activities (the second component of the programme). These activities are expected to reinforce community acceptance of MDA and are deemed essential to eliminate LF as a global public health problem.

Play now audio summary–LF
00:02:35 [mp3 1.5Mb]

Under MDA, albendazole is administered together with one of two other antifilarial drugs, ivermectin or diethylcarbamazine citrate (DEC). Albendazole is donated free of charge by GlaxoSmithKline, which has provided almost 1 billion tablets since 2000. Ivermectin is also donated free of charge to endemic countries in Africa by Merck & Co., Inc., which since 2000 has provided nearly 750 million ivermectin tablets (equivalent of 250 million treatments) for distribution. DEC is an inexpensive drug, and efforts are being made to secure adequate supplies for countries unable to meet their needs.

“This dramatic scale up shows what can be achieved if all partners work together. We have a real opportunity to eliminate this terrible disease once and for all.”

Andrew Witty, Chief Executive Officer of GlaxoSmithKline

“Merck is proud to be a part of the successful global effort to eliminate LF. We commend all of the partners who are dedicated to protecting millions of people from this dreaded disease.”

Richard T. Clark, Chairman, President and CEO of Merck & Co., Inc.

“Tackling multiple infections as a group has allowed us to focus more on the rapid expansion of treatments to millions of people. Such an integrated, population-based approach also saves time and reduces the burden to locally manage them.”

Lorenzo Savioli, WHO Director of the Department of Control of Neglected Tropical Diseases

Since 2000, more than 1 billion treatments have been delivered, significantly reducing the prevalence and intensity of the disease and preventing infection in millions of children. The focus now is on coordinated efforts to treat simultaneously other parasitic diseases such as helminthiasis, schistosomiasis and trachoma.

In the African region, more than 382 million people are exposed to LF in 39 of the 46 Member countries. During the past 10 years of LF programme implementation, 35 countries have completed mapping. In 2007, 15 of these countries* collectively treated more than 47 million people, an increase of 40% compared with the total number treated in 2006.

Benin, Madagascar, Mali, Uganda and the United Republic of Tanzania achieved remarkable scale-up so that more than 10 million new cases have been treated; this is the highest annual increase since the programme started.

Since 2000, more than 160 million treatments have been delivered in the African Region alone. Two Indian Ocean islands (Mauritius and the Seychelles) are currently verifying elimination.

In the Region of the Americas, an estimated 11 million people are at risk. Seven countries are classified as endemic but only four (Brazil, the Dominican Republic, Guyana and Haiti) reported active transmission in 2007.

MDA is being stepped up in Brazil. In Haiti, the programme is to recommence in 2008 as a result of funding from the Bill & Melinda Gates Foundation, the United States Agency for International Development and the Research Triangle Institute.

The Eastern Mediterranean region, has three endemic countries (Egypt, Sudan and Yemen). Sudan is the only country that has yet to begin MDA, as insecurity and a lack of supporting health infrastructure have hampered its implementation. A pilot MDA project in the eastern part of northern Sudan will begin shortly. Under the plan, integrated treatment for onchocerciasis, trachoma and schistosomiasis will be implemented.

In Egypt, five rounds of annual MDA have been applied to the majority of endemic areas, thus achieving the criteria of stopping MDA; however, a small number of villages failed post-MDA evaluation after five rounds of treatment and will require further rounds. A biannual round is being implemented in 29 villages.

In Yemen, all areas have been covered with five MDA rounds and have fulfilled the criteria for stopping MDA, except in Socotra where treatment may still be required.

The South East Asia region, carries the largest burden of the disease, with 9 out of 11 countries endemic. MDA has been initiated in endemic countries: India, the Maldives and Sri Lanka have achieved full geographical coverage. Sri Lanka has already completed 5 to 6 rounds and may not require any further rounds. More than 107 million people in the region have been treated with DEC and albendazole and 375 million people, almost all in India, treated with DEC alone. In 2007, India adopted the two-drug DEC-plus albendazole regimen as its national strategy.

In the Western Pacific region, China became the first country declared to have eliminated LF as a public health problem in August 2007. The Republic of Korea followed in March 2008. Cambodia, the Lao People's Democratic Republic, Malaysia, the Philippines, and Viet Nam are implementing MDA.

Of 17 endemic countries, 12 have conducted MDA, reaching 20% of the total at-risk population. The major challenge is Papua New Guinea, which represents 70% of the total population at risk in the Pacific. A plan for active post MDA surveillance has been developed in response to the risk of a resurgence of LF.

More than 120 million people around the world suffer from elephantiasis, which causes severe disfigurement and enlargement of the arms, legs and genitalia. Around 43 million people have these outward visible signs, while more than 76 million suffer from irreversible internal damage.

LF is caused by microscopic thread-like parasitic worms invading the body's lymphatic system, which is the network of vessels carrying infection-fighting cells.
See video: "transmission cycle"[wmv format]

The worm is spread by mosquitoes, which pass it on when they take blood from humans. These worms lodge in the lymphatic system, producing millions of minute larvae that spread throughout the bloodstream, triggering an imbalance of the lymphatic system, which controls the fluid balance between tissues and blood in the body.

To prevent transmission and infection, yearly administration of the drug is required over a period of 4 to 6 years to interrupt the parasite's life-cycle. Maintaining an adequate supply of drugs, both purchased DEC and donated ivermectin and albendazole, is critical to the success of MDA. Post-MDA surveillance is also crucial to prevent resurgence of the disease.

As maintaining adequate supplies of these drugs is critical to the success of country programmes, drug forecasting with pharmaceutical partners to meet country needs is absolutely necessary.

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*Benin, Burkina Faso, Cameroon, Comoros, Ghana, Kenya, Madagascar, Mali, Niger, Nigeria, United Republic of Tanzania (2 programmes: mainland and Zanzibar), Senegal, Sierra Leone, Togo and Uganda.

**Source: Weekly epidemiological record,
N° 37, 83, 333-348, www.who.int/wer/en

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