Systematic Veterinary Virology

TRANSMISSION

• The BEF virus spreads in nature only by an insect bite. The disease will not spread from cow to cow by close contact, droplet infection, bodily excretions including semen, or by the transfer or injection of exudates. Strong winds can transport vectors long distances, over land and water.
• Epizootics of BEF are associated with recent rainfall. Mosquitoes are the major vectors in spreading BEF. The BEF virus has been isolated from Culicine and Anopheline mosquitoes and biting midges.
• However, establishment of the disease depends on suitable environmental conditions for the vector to increase and spread. There is also no carrier stage as BEFV is only present in the blood for short periods during the acute stage of the diseases.