Bovine leukemia virus (BLV) was transmitted by horse flies, Tabanus fuscicostatus, from a cow with a lymphocyte count of 31,500/mm3 to goats and dairy calves. As few as 10 and 20 flies transmitted BLV to goats and calves respectively, but the minimal number of flies required to transmit the infection was not established. Groups of 150 and 100 T fuscicostatus transmitted BLV to beef calves from a cow with a lymphocyte count of 14,600/mm3. These results support a role for horse flies in the horizontal transmission of BLV.

Trypanosomiasis positive cases were reported in Sahom Farm Retreatin Gopeng, Perak; with multispecies livestock animals. Nzi and Vavoua traps were applied to survey the population of biting flies; stable flies (Muscidae: Stomoxyinae) and horse flies (Tabanidae)as the vector for surra. Results indicated the presence of Trypanosomiasis infection diagnosed by buffy coat examination, thinblood stained smears and serological test (Surra Sero K-Set test) and identification of its insect vectors. The presence of bothbiting flies provides the missing link between the occurrence of the disease and host or environmental factors precipitatingthe disease. Besides trypanosomiasis in cattle, other parasitic infections were also recorded with heavy infections for liver fluke (Fasciola gigantica ova) and coccidia oocysts. Therefore, some control measures are recommended to eradicate the vectors and to treat infected animals in order to prevent the dissemination ofthe trypanosmiasis.

Bovine anaplasmosis is the disease caused by the bacterium Anaplasma marginale. It can cause production loss and death in cattle and bison. This was a reportable disease in Canada until April 2014. Before then, infected herds were quarantined and culled, removing infected animals. In North America, A. marginale is biologically vectored by hard ticks (Acari: Ixodidae), Dermacentor variabilis and D. andersoni. Biting flies, particularly horse flies (Diptera: Tabanidae), can also act as mechanical vectors. An outbreak of bovine anaplasmosis, consisting of 14 herds, was detected in southern Manitoba in 2008. This outbreak lasted multiple rounds of testing and culling before eradication in 2011, suggesting local maintenance of the pathogen was occurring. We applied novel approaches to examine the vector ecology of this disease in this region. We did not detect A. marginale by screening of 2056 D. variabilis (2011 and 2012) and 520 horse flies (2011) using polymerase chain reaction (PCR).