Discussion of the Paper on Simulium Damnosum

Abstract

In the first decade of this century, Simulium damnosum was discovered; in the third, it was recognized as a vector of human onchocerciasis. In the fourth decade, this disease, and in many areas river blindness, was accepted as an inevitable hazard, receiving much less attention than the killing diseases, while a few enthusiasts gathered knowledge on the vector. The fifth decade was one of promise, with the advent of DDT and some spectacular successes against Simulium larvae. Between 1951 and 1960, new areas were put under control including the Abuja region of Nigeria by R.N. Crosskey (1958). The seventh decade was one of increasing knowledge and of appraisal of results. S. damnosum, once regarded as a rather uniform species, was seen to be a complex of cytological categories and morphological variants. Physiological differences between some of these variants were revealed by B.O.L. Duke’s discovery of their association with geographical forms of Onchocerca volvulus.