The development of Onchocerca ochengi in surrogate temperate Simuliidae, with a note on the infective larva
McCall, P.J.; Trees, A.J.
Tropical Medicine and Parasitology Official Organ of Deutsche Tropenmedizinische Gesellschaft and of Deutsche Gesellschaft für Technische Zusammenarbeit 40(3): 295-298
1989
ISSN/ISBN: 0177-2392 PMID: 2617036 Document Number: 341631
Laboratory-reared nulliparous female flies of 6 temperate species of Simuliidae were examined for their susceptibility to infection with O. ochengi by intrathoracic injection of cryopreserved skin microfilariae obtained from cattle in Mali. Three species (S. equinum, S. ornatum and S. erythrocephalum) supported development to the infective stage, one species (S. variegatum) allowed partial development and the remaining 2 species (S. reptans and S. aureum) were insusceptible to infection. The most suitable surrogate vectors were S. equinum and S. ornatum which had survival rates of 44% and 49%, proportions of microfilariae developing to 3rd stage larvae of 6.4% and 3%, and infection rates with infective larvae of 13.5% and 14% respectively. O. volvulus infective larvae, produced by intrathoracic microfilarial injection in S. ornatum, were 586-760 micro m (mean 687 micro m) long and were significantly shorter than the O. ochengi infective larvae (645-880 micro m, mean 756 micro m). No constant differences in the posterior or anterior morphology, or in the acid phosphatase staining patterns between O. ochengi and O. volvulus, were seen. These results raise the possibility that the presence of O. ochengi in a population of infective larvae from vector flies in endemic onchocerciasis zones might be identifiable on the basis of their length alone.