[3][4] In 1902, a Hungarian veterinarian, Aladár Aujeszky, demonstrated a new infectious agent in a dog, ox, and cat, and showed it caused the same disease in swine and rabbits.

In the following decades the infection was found in several European countries, especially in cattle, where local intense pruritus (itching) is a characteristic symptom.

This disease manifestation has always been asymptomatic in affected pigs, and presence of the infection on a farm was detected only because of cases in cattle showing pruritus on the hindquarters.

The correlation between high virulence of virus strains and syncytium formation in tissue cultures was confirmed by examinations of isolates from other countries.

New outbreaks after the eradication of the indigenous infection by the end of 1985 were all caused by foreign highly virulent, syncytial strains introduced by airborne transmission from Germany.

Populations of wild boar, or feral hogs (Sus scrofa), in the US commonly contract and spread the virus throughout their range.

Otherwise healthy male adults (boars) are typically latent carriers, that is, they harbor and transmit the virus without displaying signs or experiencing disability.

Outbreaks in farm fur species in Europe (mink and foxes) have been associated with feeding contaminated pig products.

The infection is commonly considered to be transmitted among swine through nose-to-nose contact, because the virus is mostly present in nasal and oral areas.

This notion, however, is contradicted by results from epidemiological studies, according to which the decisive spread within herds occurs by air currents over many meters.

Although no specific treatment for acute infection with PRV is available, vaccination can alleviate clinical signs in pigs of certain ages.

Concurrent antibiotic therapy via feed and IM injection is recommended for controlling secondary bacterial pathogens.

For this purpose the attenuated (less virulent) Bartha PRV strain is commonly used[15] and is employed as a retrograde[16] and anterograde[17] transneuronal tracer.

In the retrograde direction, PRV-Bartha is transported to a neuronal cell body via its axon, where it is replicated and dispersed throughout the cytoplasm and the dendritic tree.

Using temporal studies and/or genetically engineered strains of PRV-Bartha, second, third, and higher order neurons may be identified in the neural network of interest.