Animals carrying the virus are introduced into susceptible herds. Contaminated facilities are used to hold susceptible animals. Contaminated vehicles are used to move susceptible animals. Raw or improperly cooked garbage containing infected meat or animal products is fed to susceptible animals. Susceptible animals are exposed to materials such as hay, feed, hides or biologics contaminated with the virus.
Susceptible animals drink contaminated water.
A susceptible cow is inseminated with semen from an infected bull. The last outbreak in Washington was in 1914. In Japan, officials said 10 cows showed symptoms of the disease March 12. All 10 animals were destroyed. There, the disease is in dairy cows.