LYMPHATIC FILARIASIS

This web site was created for help in spreading the knowledge about lymphatic filariasis specially the most prevalent form of the disease: bancroftian filariasis (see below). Questions and suggestions are welcome at amaurycoutinho@uol.com.br care of Gerusa Dreyer.

Lymphatic filariasis is a disease caused by parasitic worms that are spread from person to person by mosquitoes. When mosquitoes feed on people who have microfilaria in their blood, they take up the microfilaria in the blood meal. The microfilaria develop inside the mosquito. Few days after when a mosquito takes a new human blood meal, the worms are deposited on the surface of the human skin; they enter the skin, find their way to the lymphatic vessels, and, during a period of 6 to 12 months, develop into adult worms. The adult worms mate and the females release millions of tiny worms, called microfilaria (or baby worms). Microfilariae live in the blood, and can be seen only with a microscope. The mosquitoes are required to spread the worms from one person to another.

Two different types of worms can cause lymphatic filariasis in humans. About 90% of infections are caused by the worm Wuchereria bancrofti. This type of filariasis, known as bancroftian filariasis, occurs in Africa , Asia , the Pacific Islands , and the Americas . Brugia malayi, which occurs in Asia and some Pacific islands, accounts for about 10% of human filariasis.

- Eliminating lymphatic filariasis (LF)
In 1998, the World Health Organization announced a program to eliminate lymphatic filariasis infection throughout the world. Drugs are now available that, when taken in a single dose kill microfilaria and keep the blood free of them for up to a year. This prevents mosquitoes from spreading lymphatic filariasis from one person to another. The drugs that kill the microfilaria do not kill all the adult worms, which live for 5 to 10 years and may continue to produce microfilaria. Therefore, annual treatment to kill microfilaria must be continued for several years.

- Medication for people with microfilaria in their blood
In many areas where lymphatic filariasis occurs, blood examination for microfilaria is available. People who have microfilaria in their blood should be treated with drugs to kill the worms. In some areas, these drugs may only be available during the once-a-year treatment for all members of the community. If this is the case in your area, advise anyone who is known to be microfilaria-positive about the importance of taking the antifilarial drugs during the next drug distribution.

In places without mass treatment, people need to be aware where they can have their blood tested for microfilaria. If microfilariae are found in the blood, infected people need treatment with antifilarial drugs. Usually antifilarial drugs should be available at the clinic where blood is tested for microfilaria.

- The disease and its management
Bancroftian filariasis may cause a variety of medical problems. In men the most common problem is the excess fluid inside the scrotal sac or hydrocele. People may also have swelling in the legs, arms, breasts, scrotum, and penis. This swelling is called lymphedema. You may have heard the term elephantiasis, which refers to the most advanced stages of lymphedema. Many people with lymphatic filariasis have no obvious signs of disease, although their lymphatic vessels are already damaged, and they are at risk of developing disease.

The major goal of lymphedema management in filariasis-endemic areas is to prevent acute attacks caused by bacterial infections. For people with no signs of lymphedema, but whose lymphatic vessels are already damaged by filarial worms, preventing the initial acute attack will avoid the appearance of lymphoedema. For patients with lymphoedema, preventing recurrent acute attacks will halt the progressive course of lymphedema and elephantiasis. To learn more click here. A 21 minutes video about lymphedema and how to avoid acute episodes are available in this web site. Some frequent questions and answers about filariasis can be found in the virtual folder.