Nasal virus spreads to young piglets (<3 w.o.) via aerosol to cause a bronchopneumonia and then viraemia. In piglets the neurones are infected to cause a encephalitis with convulsions from which they usually recover. Sows sometimes abort.

Dogs, cats, cattle, sheep at shearing, can become infected by aerosol virus from pigs which enters skin lesions to cause intense pruritis at the site of entry then axoplasm spread to the brain with death from pseudorabies.

Pruritis but not encephalitis has been recorded in lab workers.

Spread and control

Latent virus may be reactivated by the stress of bringing in and mixing new stock.