Man-biting species of Chrysops Meigen, Culicoides Latreille and Simulium Latreille in Ethiopia, with discussion of their vector potentialities

Abstract
Human filariasis and its vectors are little known in Ethiopia. Wuchereria bancrofti is confined to the western lowlands and cannot be the aetiological agent of elephantiasis in the highlands. Onchocerca volvulus is widespread in the south-western highlands. Loa loa and Dipetalonema persians are reported here for the first time and appear to be uncommon. Studies were conducted in 1973, mostly near Jimma in Kaffa Province, on potential vectors of all but the first of these parasites. Among Simuliidae, the only blackflies of apparent medical importance were S. woodi ethiopiense and a possibly new member of the S. damnosum complex. The former is less seasonal and much less numerous than the latter, but may be more widespread and important along smaller and higher streams. Onchocerca larvae were recovered from “damnosum”, but not from the small number (46) of ethiopiense examined. In August, at the height of the rainy season, the biting-rate of ethiopiense at 1,710 m altitude on the Gilgil Ghibe river reached 9·5/man-hour at 10–1100 hours and about 12/man-hour at 14–1600 hours. At the same time and place, the attack of “damnosum” reached a midday climax of about 1,800/man-hour; this peak could be delayed or suppressed by rain. Another possibly anthropophilic blackfly, S. dentulosum, tended to become most common in December after the rainy season had passed, but proved incompetent to bite man successfully. The only feasible loiasis vector found in Ethiopia was Chrysops streptobalius; however, this tabanid was not closely associated with man. Up to 34/man-day were caught in watermeadows by the Gojeb river (altitude 1, 160m) in October. Man-biting species of Ceratopogonidae in various parts of Ethiopia were Culicoides fulvithorax, C. grahamii, C. kingi and C. milnei. The first two of these were anthropophilic in lowlands, but apparently not so in highlands. C. milnei was extremely abundant biting man and domestic animals both indoors and outdoors at Jimma and was widespread elsewhere in the highlands. Its biting cycle was irregular, usually displaying a succession of ill-defined nocturnal peaks; sometimes it attacked in daylight. Up to 35,000 C. milnei per trap-night were caught in light traps. Most of the females entering light traps in a stable were already engorged with blood. It seemed very likely that C. milnei would prove to be of veterinary importance. No firm indication was obtained as to what may transmit D. perstans in Ethiopia.