The virus, a herpes virus, is easily spread between farms and also has the ability to produce latent infections.
Evidence indicates that the pig is the only primary host of pseudorabies.
In fact, pseudorabies causes an acutely fatal infection in most non-porcine species. An infectious dose of virus is required before infection takes place. This dose varies with species and age. Basically, transmission of infection is by ingestion or inhalation of the virus particles. Once infected, swine may develop clinical infection and shed virus.