Infection with the filarial worm, Wuchereria bancrofti. The adult worms migrate to the lymphatic system producing recurrent lymphangitis with obstruction and fibrosis. Edema progresses to elephantiasis. Transmitted by mosquitoes, which harbor the larval forms. Usual course - chronic; relapsing; 8-12 month incubation. Endemic areas - Africa; Pacific islands; Southeast Asia; West Indies; Central America; eastern coastal plains of South America.