filariasis /fil′ərī″əsis/ [L, filum, thread; Gk, osis, condition] , a disease caused by the presence of filariae or microfilariae in body tissues. Filarial worms are round, long, and threadlike and are common in most tropic and subtropic regions. They tend to infest the lymph nodes, lymphatics, subcutaneous tissues, and skin after entering the body as microscopic larvae through the bite of a mosquito, blackfly, or midge. The infection is characterized by occlusion of the lymphatic vessels, with swelling and pain of the limb distal to the blockage. After many years the limb may become greatly swollen and the skin coarse and tough. Treatment is by oral administration of diethylcarbamazine, ivermectin, albendazole, or mebendazole. Apheresis, antihistamines, and corticosteroid therapy may be performed before the administration of antihelmenthic agents to reduce the risk of reaction associated with heavy worm burden. The most effective means of preventing infestation is flying insect control. See also elephantiasis, Loaloa, Mansonella, onchocerciasis, Wuchereria.
