Onchocerciasis. African children leading women blinded by onchocerciasis (river blindness"). This type of filariasis is caused by the infective tiny worms (microfilariae) of Onchocerca volvulus. The larvae are transmitted from person to person by biting flies which breed in and live around rivers. The larvae grow into adults which produce the tiny worms. Blindness occurs as an allergic reaction when these worms die in or near tissues of the eye. Childhoods are lost through the constant caring that blind relatives require. The worms can be effectively treated using drugs. Photographed in Sudan."