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Aujeszkys Disease (AD) - Pseudorabies (PR)

See also chapter 12.

(408) This is caused by a herpes virus and is a very important disease. The pig is the only natural host and the virus can maintain itself hidden in nervous tissue for long periods of time. It can affect other species including cattle, horses, dogs and cats but these always die. There are no confirmed reports of it affecting people. The outer covering of the virus contains proteins called glycol proteins which are numbered G1, G2 and G3. If one or more of these are removed by genetic engineering, the virus can no longer produce the disease but can still stimulate an immunity. Such viruses are called gene deleted and are used to produce live vaccines. Field virus can be spread between herds by sub-clinical carrier pigs, usually replacement breeding stock, and on the wind. Wind-borne infection can occur over distances of several kilometres over land and much further over water. It can also be spread by AI. Within herds it may be spread direct by nose to nose contact, or by aerosol droplets.

The virus has been eradicated or kept out of some countries (e.g. Chile, Australia, Denmark and Great Britain) and attempts to eradicate it are being carried out in other countries (e.g. USA, Ireland and the Low Countries), but in other countries it is endemic and widespread. Eradication polices range from slaughter depopulation and repopulation, to the use of gene deleted vaccines to identify by blood sampling those pigs that are carrying the disease. They can then be eliminated from the population over a period of one to two years. Because the disease is relatively slow spreading it can be eliminated.

Clinical signs

Acute disease
When first introduced into a herd AD infects the reproductive tract with high mortality in unborn piglets in utero and during sucking. In the growing period there may be fever, sneezing, coughing, pneumonia and high mortality with some nervous signs including incoordination and fits. Some strains of the virus cause severe respiratory disease and others severe rhinitis in growing and finishing pigs and complicate already existing respiratory problems.


This is based on the clinical picture, serological and laboratory tests.


  • There is no specific treatment for AD, but in-feed antibiotics may help to control secondary bacterial infections during the exposure to the virus.
Management control and prevention
  • In growing pigs the maintenance of a disease free breeding herd must be aimed for.
  • In aujeszky free breeding herds, prevention is dependent on stopping the virus entering the herd by screening the sources of purchased replacement stock and blood sampling them in isolation prior to entry into the herd.
  • If the breeding herd is in a country in which the infection is widespread then it may be good insurance to vaccinate the sows with gene deleted vaccine to prevent disease entering or at worst reduce the major piglet losses that can occur when the virus first enters a susceptible herd.
  • The use of a gene deleted vaccine also allows the herd to be tested serologically to check that the virus has not entered.
  • If the breeding herd is already endemically infected then the sows should be vaccinated routinely together with all growing pigs.

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