Lymphatic Filariasis Disease - Carter Center

Wuchereria bancrofti vespid, Immune response, Serum immune complexes diagnosis, Diethylcarbamazine (DEC), Wolbachia in filarial parasites, Interdigital skin lesions, Urban Filariasis, Doxycycline, mass drug administration program, Filarial Lymphedema Care, Detection of filarial parasites, Albendazole, research abstracts

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Lymphatic Filariasis Disease - Carter Center

Postby patoco » Fri Jul 07, 2006 8:08 am

Lymphatic Filariasis Disease - Carter Center - Lymphatic Filariasis Program

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Lymphatic Filariasis Disease - Carter Center Lymphatic Filariasis Program

According to the World Health Organization, lymphatic filariasis is a leading cause of permanent and long-term disability. In its severest form, lymphatic filariasis leads to elephantiasis-a crippling condition in which limbs or other parts of the body are grotesquely swollen or enlarged. In communities endemic with lymphatic filariasis, as many as 10 percent of women can be affected with swollen limbs and 50 percent of men can suffer from mutilating genital disease. These conditions have a devastating effect on the quality of life of those affected, impacting them not only physically, but also emotionally and economically.

Lymphatic Filariasis Elimination Program

In a collaborative effort, The Carter Center and its partners are investigating whether transmission of lymphatic filariasis, a devastating disease that can cause elephantiasis, can be interrupted on a large scale in Africa.

There are approximately 1.1 billion people at risk for contracting lymphatic filariasis and 120 million people infected worldwide. Nigeria is the third-most endemic country in the world, with an estimated 22 million cases. According to the World Health Organization, India, Indonesia, Nigeria, and Bangladesh account for 70 percent of all infections worldwide. Estimates of annual economic loss in India due to lymphatic filariasis approach $1 billion USD; the economic impact in Nigeria is unknown, but is expected to be significant.

Transmission of Lymphatic Filariasis

Lymphatic filariasis is a parasitic worm transmitted by the bites of mosquitoes in tropical and subtropical regions of the world. Several species of mosquitoes can transmit the disease, but in rural Africa the Anopheles mosquito is the primary carrier for both lymphatic filariasis and malaria.

When a mosquito bites a person who has lymphatic filariasis, microscopic worms called microfilariae (baby worms) circulating in the person's blood enter and infect the mosquito. While inside the mosquito, the microfilariae develop over a period of a week into an infectious stage, called larvae.

The infected mosquito deposits microscopic larvae on the skin while biting a person and the larvae enter the bite wound migrating to the human lymph system, where they mature. The transmission of lymphatic filariasis is inefficient, a reason for the disease's potential for eradication.

In the lymphatic system, adult worms mate and form nests, which cause blockages resulting in swelling and fever. Female worms produce millions of microfilariae that swarm in the blood at night when mosquitoes bite, continuing the cycle. Adult worms live for about five to seven years.

While infections are contracted throughout life, most individuals can remain asymptomatic for years, with symptoms emerging during adolescence and adulthood.

Strategies for Eliminating Lymphatic Filariasis

Lymphatic filariasis is one of six diseases the Carter Center's International Task Force for Disease Eradication determined could be eradicated using current tools and technologies. Read the ITFDE summary (PDF). In 1997, through the recommendation of the task force, the World Health Organization advocated for the global elimination of lymphatic filariasis as a public health problem.

The strategy for elimination is based on the use of mass community treatment to kill the microfilariae to stop transmission of the parasite by mosquitoes. The Carter Center uses a combination treatment comprised of two drugs: ivermectin (Mectizan®, donated by Merck & Co., Inc.) and albendazole (donated by GlaxoSmithKline). Combination treatment better reduces the number of microfilariae in blood.

Diethylcarbamazine, often referred to as DEC, is the third drug used in the fight against lymphatic filariasis although its use is not recommended for mass chemotherapy in Africa.

Studies have demonstrated that transmission of the infection can be broken when a single dose of combined oral medicines is consistently maintained annually for approximately seven years. In other words, with consistent treatment, the reduction of microfilariae means the disease is not being transmitted, the adult worms will die out, the cycle will be broken, and mass treatments can be halted.

Another important strategy that can be combined with mass treatment is the use of insecticide-treated mosquito nets, being advocated widely through Africa for control of malaria. Reducing mosquito bites adds another layer of prevention to stop lymphatic filariasis transmission. The Carter Center, with Nigeria Ministry of Health, is pioneering the use of insecticide-treated mosquito bed nets to help reduce transmission of both diseases.

The Carter Center and Lymphatic Filariasis in Nigeria

Nigeria is the most endemic nation for lymphatic filariasis in Africa and is the third-most endemic country in the world after India and Indonesia. Such compelling statistics and an invitation from the Nigeria Ministry of Health brought The Carter Center and other partners together in an effort to eliminate the disease from Nigeria by 2015.

Currently, the Center is working with two states in Nigeria, Plateau and Nasarawa, to demonstrate that the disease can be completely eliminated by distributing the safe combination of Mectizan and albendazole. The drug combination is distributed at the village level, and the dose is determined by height-a sufficient estimate of weight in most developing countries.

In 2004 and 2005 more than 3 million people were treated annually. In a few pilot areas endemic for both lymphatic filariasis and malaria, approximately 57,000 insecticide-treated bed nets, donated by the National Malaria Program, have been distributed. Assessments underway to determine the impact of these interventions have already shown a reduction of greater than 80 percent in lymphatic filariasis in both people and mosquitoes. The significant reduction illustrates the important contribution bed nets can make in the fight against lymphatic filariasis.

Disease Integration

The Carter Center's Lymphatic Filariasis Elimination Program is based on the same community education and drug distribution system as the Center's River Blindness Program. In fact, the drug Mectizan, which is used in combination with albendazole to prevent transmission of lymphatic filariasis, is the same drug used worldwide to prevent transmission of river blindness. After years of success distributing Mectizan for river blindness in Nigeria (treatments began in 1993), the Center began a pilot project to determine the feasibility of adding albendazole to the treatment regimen in communities where both river blindness and lymphatic filariasis are endemic. Additionally, the Center and Nigeria Ministry of Health added a Schistosomiasis Control Program in villages where schistosomiasis occurs alongside river blindness and lymphatic filariasis. The Schistosomiasis Control Program distributes the safe and effective oral tablet praziquantel.

The success of the integrated programs has so far been predicated on the idea that safe and effective miracle medicines, with health education, can be distributed at scale using community workers and volunteers, to change lives. The programs have overwhelmingly demonstrated that one community-based health education and drug distribution system can support the control and elimination of multiple diseases. The Carter Center's work in integration is widely recognized as a truly pioneering effort.

Lymphatic Filariasis Partnerships and Support

Elimination of lymphatic filariasis is only possible through collaboration with multiple organizations and agencies. The Carter Center partners with Nigeria's Federal Ministry of Health and the ministries of health in Plateau and Nasarawa States, as well as the Emory University Lymphatic Filariasis Support Center, the Centers for Disease Control and Prevention, the Bill & Melinda Gates Foundation, Merck, and GlaxoSmithKline. Most of all, through committed community action, Nigerians themselves are freeing their families and friends from the misery of lymphatic filariasis.

Updated May 2006

Although programs fighting lymphatic filariasis exist worldwide, the 1998 partnership between the Nigeria Ministry of Health and The Carter Center was the first time the disease had been targeted in Nigeria, the third-most endemic country in the world. Furthermore, the Center's model of distributing drugs for several diseases through one community distribution system is setting the standard for integrated public health systems in all developing countries.
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