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 is discussed for tabanid transmission of viruses, bacteria, Protozoa and helminths. The results of laboratory and field tests indicate that tabanids are essential to the biological transmission of the Protozoa Haemoproteus metchnikovi and Trypanosoma theileri and of the helminths Loa loa, Dirofilaria roemeri and Elaeophora schneideri, and that tabanids are mechanical vectors of the viruses of equine infections anaemia, vesicular stomatitis, hog cholera and rinderpest, the bacteria Anaplasma marginale, Bacillus anthracis, Clostridium chauvoei, Pasteurella multocida, P. tularensis (Francisella tularensis), Brucella spp., Listeria monocytogenes and Erysipelothrix rhusiopathae, the Protozoa Besnoitia besnoiti, T. evansi, T. equiperdum, T. congolense, T. brucei brucei and T. rhodesiense. The extent of the importance of tabanids in the natural mechanical transmission of most of these agents is not known. Indirect modes of transmission, involving secondary blood-feeding insects at the sites of tabanid bites or contamination by means of agents adhering to external tabanid structures are briefly discussed.