ANIMAL-DISEASE AGENTS TRANSMITTED BY HORSE FLIES AND DEER FLIES (DIPTERA-TABANIDAE)

Published reports of tabanid transmission of pathogenic agents of animals (including man) are reviewed. Experimental evidence for tabanid transmission of the following disease agents is discussed: viruses (equine infectious anemia, vesicular stomatitis, hog cholera, rinderpest, equine encephalitides, tick-borne encephalitis); bacteria (Anaplasma marginale, Coxiella burnetii, Bacillus anthracis, Clostridium chauvoei, Pasteurella multocida, Francisella tularensis, Brucella spp., Listeria monocytogenes, Erysipelothrix rhusiopathiae, Leptospira spp.); protozoa [Besnoitia besnoiti, Haemoproteus metchnikovi, Theileria tarandi rangiferis, Trypanosoma theileri, T. evansi, T. equiperdum, T. vivax, T. congolense, T. simiae, T. brucei brucei, T. b. gambiense (rhodesiense)]; and helminths (Loa loa, Dirofilaria repens, D. roemeri, Elaeophora schneideri, Onchocerca gibsoni). Results of laboratory and field studies indicate that tabanids are essential for the biological transmission of H. metchnikovi, T. theileri, L. loa, D. roemeri and E. schneideri and that tabanids are mechanical vectors of the viruses of equine infectious anemia, vesicular stomatitis, hog cholera and rinderpest; the bacteria A. marginale, B. anthracis, C. chauvoei, P. multocida, F. tularensis, Brucella spp., L. monocytogenes, E. rhusiopathiae; and the protozoa B. besnoiti, T. evansi, T. equiperdum, T. congolense, T. brucei brucei, T. b. gambiense (rhodesiense). The extent to which tabanids are important in the natural mechanical transmission of most of these agents is not known. Indirect modes of transmission involving secondary blood-feeding insects (at tabanid bite sites) and contaminative transmission of agents adherent to external tabanid structures are briefly discussed.