On the Development, in Culicoides furens Poey, of Filaria (= Mansonella) ozzardi Manson, 1897

The life-cycle of Filaria ozzardi was studied in St. Vincent, B.W.I. 2. Culicoides furens Poey, a common sandfly in Calliaqua, where a 37·7% human infection was found, was used in the experimental infections. 3. Two hundred sand-flies, collected at Calliaqua, were given an infective feed of blood of F. ozzardi carriers. Of these flies, fifty-five, i.e. , 27·5%, were subsequently found to be infected with developing stages of the parasite. The ingested microfilariae migrated within 24 hours to the thorax, where the entire morphological development takes place. In flies which were kept alive for seven or eight days, advanced stages were found in the thorax and head, and their emergence from the proboscis was induced by slight pressure on the head. 4. The development in the sandfly consists of a metamorphosis from the 1st stage or “sausage” larva to a 2nd stage larva during the first 3 to 4 days, and from this stage to a 3rd stage or infective larva on the fifth or sixth day. Two ecdyses occur during these metamorphoses, which are discussed in relation to the other human filarial parasites. 5. Five per cent. of C. furens caught at Calliaqua were found to be naturally infected with developing larvae, apparently F. ozzardi . 6. The possibility that C. paraensis , another species in Calliaqua, may also act as a vector, is not excluded.