The in vitro culture of Onchocerca spp.: I. Preliminary observations on the development of the second to the third stage larvae.

Second stage larvae of Onchocerca lienalis and O. gutturosa were induced to moult successfully to the third stage in vitro. Following development in their vectors Simulium ornatum s.l. and Culicoides nubeculosus the second stage larvae were kept in a cell free culture system. At least 25% of the second stage larvae of either Onchocerca species completed the moult successfully although no feeder layers had been used. In the absence of CO2 (5% in air) the number of the second stage larvae moulting successfully to the infective stage dropped to 6 and 9% respectively.