Intake and Migration of the Microfilariae of Onchocerca volvulus (Leuckart) in Simulium damnosum Theobald

Abstract

1. The intake of microfilariae of Onchocerca volvulus in two series of females of Simulium damnosum fed on an infected human volunteer in West Africa and dissected after staining in London was from 0–171 microfilariae per female in one series and from 0–152 microfilariae per female in the other series. The distribution of microfilariae per female became more normal when plotted on a geometric scale.2. The migration of the microfilariae was followed in the two series of flies by comparing the geometric (Williams) mean numbers of microfilariae in the stomach, abdomen, thorax and head, from 2 minutes to 48 houis after engorgement on blood. Microfilariae left the blood meal rapidly after engorgement, 40–50% leaving the stomach within the first 60 minutes.