Until the sixties BHVI was known in Europe to cause coital exanthema in bov
ines as coital exanthema virus. In the USA, however; reports have already s
hown the serological identity between the viruses causing infectious bovine
rhinotracheitis (IBR), conjunctivitis and the genital tract viruses.
The high losses in the USA lead to a fast development of parenterally appli
cable attenuated vaccines. The occurrence of IBR and increasing numbers of
genital infections mainly in artificial breeding centres in Gel-many lead t
o the development of a locally administered attenuated vaccine originating
from a genital strain. Next the phenomenon of latency was detected in the U
SA and Australia. Vaccinations cannot prevent it.
The development of marker vaccines makes it possible to differentiate betwe
en vaccinated and previously field vir-us infected animals. But these vacci
nes are also unable to prevent later infections followed by a latent state.
If the marker vaccines ar-e live, it is possible that following an immunos
uppression both viruses, field and vaccine are excreted.