AETIOLOGY:

PRV belongs to the genus Varicellovirus in the subfamily Alphaherpesvirinae of the family Herpesviridae.

CLINICAL SIGNS:

Pseudorabies is a disease of swine that can also affect cattle, dogs, cats, sheep, and goats. Pseudorabies virus (PRV) is a contagious herpesvirus that causes reproductive problems, (abortion, stillbirths), respiratory problems and occasional deaths in breeding and finishing hogs. Infected newborn pigs may exhibit central nervous system clinical signs.

TRANSMISSION:

PRV is primarily spread through direct animal-to-animal (nose-to-nose) contact between an infected, shedding pig and a noninfected pig. It may also be spread by sexual contact. If present on inanimate objects, such as boots, clothing, feed, trucks, and equipment, the virus can also spread from herd to herd and farm to farm.

LESIONS:

Clinical signs in pigs depend on the age of the affected animal. In piglets central nervous systems signs, incoordination, sneezing, coughing, and high mortality. In adult pigs coughing, fever, pneumonia, central nervous systems signs, and reproductive signs such as failure to breed, abortions, mummified piglets, stillbirths, and small litters. Adult pigs often have low mortality and the virus can remain hidden in the pig in a carrier state for long periods of time.

DIAGNOSIS:

Suspected based on reproductive failure in sows, along with high mortality and CNS signs in piglets. It have to be confirmed by serology, PCR or virus isolation.

Many serologic tests are now available, including serum neutralization, ELISA, and latex agglutination. A differential ELISA has been used to differentiate antibodies produced as a result of vaccination from those produced as a result of natural infection. The vaccines used in swine are based on the deletion of certain genes (gI, gIII, or gX) from the vaccine virus. Swine vaccinated with a gene-deleted vaccine do not mount an antibody response to the protein coded for by the deleted gene. In contrast, infection with field virus results in antibodies against these proteins.

TREATMENT, PREVENTION AND CONTROL:

There is no specific treatment for acute infection with pseudorabies virus. Regular vaccination results in excellent control of the disease. Mass vaccination of all pigs on the farm with a modified-live virus vaccine is recommended to reduce viral shedding and improve survival. It is recommended that breeding herds be vaccinated quarterly and that finisher pigs be vaccinated after levels of maternal antibody decrease. Numerous programs have been developed for eradication of pseudorabies virus.