The Development of Onchocerca Volvulus in Laboratory-Reared Simulium Damnosum Theobald

Simulium damnosum, the main vector of human onchocerciasis over a large part of tropical Africa, shows no reluctance to attack and bite man in nature. In the laboratory, however, it has always proved to be an extremely refractory insect, most workers having experienced the greatest difficulty in persuading it to feed in captivity. This feature is not peculiar to Similium damnosum but is also exhibited by several other medically important species of Simulium, including the vectors of onchocerciasis in Central America.As a result of this almost insuperable difficulty the great bulk of evidence incriminating Simulium as a vector of onchocerciasis has had to be based on the use of wild flies, the general method being to expose a suitable human subject to the bites of wild flies in the open and collecting the engorged flies in tubes.