Transmission Of BVD
BVDV rapidly loses infectivity outside the host, and is very susceptible to detergents, light, temperature changes and other environmental conditions. It is mainly transmitted by close contact with persistently infected or acutely infected cattle via the oral or nasal routes. Acutely infected animals only shed the virus for a short time (about 2 weeks1), whereas PI animals shed constantly in all bodily secretions for life. Acutely infected bulls shed virus in their semen for at least 2 weeks; PI bulls shed virus constantly in their semen, thus, semen is another potential source of infection in natural mating.