Orbivirus infections in cattle

Transplacental orbivirus infection in cattle usually produces only inappare nt infection; most infected dams give birth to healthy uninfected offspring . However, sporadic disease outbreaks have been reported. In cattle, blueto ngue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) produce sim ilar clinical signs. Mortality is generally low in both diseases. Both BTV and EHDV are transmitted by small biting flies of the genus Culicoides. Alt hough there is no particular species as a reservoir of EHDV, cattle infecte d with BN are considered to be reservoir hosts from which the virus may be transmitted to sheep and susceptible wildlife ruminants. Recovered animals are immune to reinfection with the homologous serotype.