Tuesday, February 24, 2009

Causes of Elephantitis



True elephantiasis is the result of a parasitic infection caused by three specific kinds of round worms. Three kinds of round worms cause elephantiasis filariasis: Wuchereria bancrofti, Brugia malayi, and Brugia timori. Of these three, W. bancrofti makes up about 90% of the cases.The long, threadlike worms block the body's lymphatic system—a network of channels, lymph nodes, and organs that helps maintain proper fluid levels in the body by draining lymph from tissues into the bloodstream. This blockage causes fluids to collect in the tissues, which can lead to great swelling, called "lymphedema." Limbs can swell so enormously that they resemble an elephant's foreleg in size, texture, and color. This is the severely disfiguring and disabling condition of elephantiasis.
There are a few different causes of elephantiasis, but the agents responsible for most of the elephantiasis in the world are filarial worms: white, slender round worms found in most tropical and subtropical places. They are transmitted by particular kinds (species) of mosquitoes, that is, bloodsucking insects. Culex, Aedes, and Anopheles mosquitoes are the carriers of W. bancrofti. Anopheles and Mansonia mosquitoes are the carriers of B. malayi. In addition, Anopheles mosquitoes are the carriers of B. timori.Infection with these worms is called "lymphatic filariasis" and over a long period of time can cause elephantiasis.
Lymphatic filariasis is a disease of underdeveloped regions found in South America, Central Africa, Asia, the Pacific Islands, and the Caribbean. It is a disease that has been present for centuries, as ancient Persian and Indian writings clearly described elephant-like swellings of the arms, legs, and genitals. It is estimated that 120 million people in the world have lymphatic filariasis. The disease appears to be spreading, in spite of decades of research in this area.The adult worms can live from about three to eight years. Some have been known to live to 20 years, and in one case 40 years. The adult worms begin reproducing numerous live embryos, called microfilariae. The microfilariae travel to the bloodstream, where they can be ingested by a mosquito when it takes a blood meal from the infected person. If they are not ingested by a mosquito, the microfilariae die within about 12 months. If they are ingested by a mosquito, they continue to mature. They are totally dependent on their specific species of mosquito to develop further. The cycle continues when the mosquito takes another blood meal.





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