Infectious Diseases: Filariasis—Bancroftian filariasis, Malayan filariasis, Loiasis (loa loa), Onchocerciasis (river blindness)

Abstract

Agents and Vectors: The filarial parasites are tissue-dwelling nematodes (roundworms) whose microfilaria (MF) larvae are transmitted by several species of mosquitoes or flies as follows (Bell, 1995; Chin, 2000; King, & Freedman, 2000; Nutman, & Weller, 1998): • Bancroftian filariasis is caused by the nematode Wuchereria bancrofti, transmitted by Anopheline mosquitoes, and occurs in much of the tropical and subtropical world (except western South America and Northern Australia) between the Tropics of Cancer and Capricorn, and primarily in cosmopolitan areas in India, China, and Indonesia. • Malayan filariasis is caused by the nematode Brugia malayi, transmitted by Mansonia or Anopheline mosquitoes, and occurs primarily in Malaysia, Indonesia, and some nearby Pacific Islands, as well as scattered areas of India, Bangladesh, Vietnam, and China. Brugia timori infections are similar, are confined to Timor and nearby (Indonesian) islands, and transmitted by Anopheles barbinostris, which also carries malaria. • Loiasis (loa loa) is caused by the nematode Loa loa (African eye worm), is transmitted by Chrysops (red or deer) flies, and occurs in West and Central Africa. • Onchocerciasis (river blindness) is caused by the nematode Onchocerca volvulus, and is transmitted by Simulium blackflies. Onchocerciasis occurs primarily in Africa, South and Central America, and the Middle East. The vectors breed only in swiftly moving water, hence endemic areas are confined to such locales.