Failure of Onchocerca gutturosa to develop in Simulium soubrense and Simulium yahense from Liberia.

Laboratory reared female S. soubrense and S. yahense from Liberia were intrathoracically inoculated with bovine skin dwelling microfilariae of Onchocerca gutturosa. Of a total of 174 flies, each injected with 50 fresh microfilariae, the maximum development was to late first-stage larvae. One S. soubrense also contained two second-stage larvae and a maldeveloped third-stage larvae. No development to normal third-stage larvae was observed in any fly despite maintenance at 28 degrees C for up to 10 days following infection. This contrasts with complete development of O. volvulus in both blackfly species under similar conditions.