3) Onchocerciasis

Historical view The parasite, Onchocerca volvulus, was first detected in a Ghanaian by a German missionary in 1890 and was nominated Filaria volvulus by Leuckart (1893). No pathogenicity of the parasite was found yet. In 1915, however, R. Robles reported the new distribution of this filarial parasite in Guatemala, Central America, after enormous parasitological, clinical and epidemiological studies of coastal erysipela (Erisipela de la costa). He clarified that O. volvulus caused ocular lesion and the denodulization improved the symptoms remarkably. This is the reason that the Government of Guatemala launched denodulization campaign in the endemic areas since 1935. Based on the specimens obtained by Robles and other information on vector blackfly species, Brumpt (1919) proposed O. caecutiens n.sp., while this new species was neglected by various parasitologists. Identification of vector insect blackfly by Blacklock in 1926 clarified transmission mechanism and encouraged vector control trials in Africa (Garnham and McMahon, 1947) in particular the Onchocerciasis Control Program (OCP) in late 1960s. A filaricide drug Diethylcarbamazine (DEC) showed curative effect, while it caused severe accessory reactions in the infected people as seen in Mazzotti reaction. Thus the mass treatment has been considered difficult before the appearance and registration of Ivermectin (Mectizan). Mass treatment by lvermectin based on the community based system recently accelerated African Program for Onchocerciasis Control (APOC) in Africa and Onchocerciasis Eradication Program of America (OEPA) in Central and South Americas in 1990s.