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Pseudorabies

By: Wildlife Futures Team Date: Apr 21, 2021

Other names: Aujeszky’s Disease, Mad Itch

Cause

Pseudorabies is caused by suid herpesvirus 1, a herpesvirus of swine. Though its name may be misleading, pseudorabies is not actually related to the rabies virus. The disease was first described in Europe in 1902, though a similar illness was reported as early as 1813 in the United States in cattle, dogs, and cats. The virus was isolated in 1910 and its association with the clinical signs was established in 19311.  

Significance

Pseudorabies is a major concern in the swine industry. Infected feral swine can potentially spread the virus to domestic swine resulting in significant economic losses2.  

Species Affected

Domestic and wild swine are the primary hosts of pseudorabies, but the disease can be transmitted to many other species. The virus is known to infect deer, foxes, raccoons, skunks, opossums, bears, rodents, wolves, coyotes, and mink3. Pseudorabies has also been reported in a Florida panther4.  

Cattle, goats, dogs, and cats are susceptible to the disease following contact with infected swine, but horses appear to be immune. Human infections are rare3. The first known human case was documented in 2017 in a person working with domestic swine that were infected; clinical signs included a high-grade fever, headache, tonic-clonic seizures, and eventually a coma5. 

Distribution

Pseudorabies occurs worldwide. The United States and many other countries have implemented eradication programs6. As of 2004, all states in the US are considered free of pseudorabies in domestic pig populations. However, feral swine present the constant threat of reintroducing pseudorabies to domestic swine in the United States7.  

Transmission

In domestic swine the virus is primarily transmitted via inhalation of or direct contact with infected nasal or oral fluids8. In feral swine, pseudorabies is transmitted mainly during mating. The virus can also be acquired by feeding on infected carcasses1. Pseudorabies virus can survive outside of the host and be transported to new habitats or farms on boots, clothing, trucks, and other equipment2. 

Clinical Signs

Adult swine may exhibit respiratory distress. Pregnant females may abort or have still born young. Infected adults will survive and become lifelong carriers of the virus with minimal or no clinical signs. Pseudorabies causes neurologic disease and high death rates in newborn piglets8. Pseudorabies can cause sudden death and is highly fatal in species other than swine. Some animals experience “mad itch”, which causes them to scratch and bite themselves. Clinical signs in non-swine species may also include respiratory problems, fever, and additional neurological signs1.  

Diagnosis

Pseudorabies is diagnosed by isolating the virus from brain, spleen, or lung tissue, or from nasal or genital swabs8. 

Treatment

There is no treatment for pseudorabies in swine, so efforts are focused on prevention2.  

Management

In 1989 the United States Department of Agriculture began a voluntary pseudorabies eradication program. This program establishes state regulations, surveys and monitors domestic swine herds for the disease, and mandates decontamination of the herds if pseudorabies is found. Management efforts must focus on eradication of feral swine and prevention of contact with other susceptible species in order to prevent the disease from negatively impacting wildlife, as well as domestic swine2.  

References

  1. Samuel, W.M., Pybus, M.J. and Kocan, A.A., 2001. Parasitic Diseases of Wild Mammals (No. Ed. 2). Iowa State University Press.
  2. USDA, APHIS, Technical Bulletin No. 1923. 2008. Pseudorabies (Aujeszky’s Disease) and its eradication: a review of the U.S. experience.
  3. Sehl, J. and Teifke, J.P., 2020. Comparative pathology of pseudorabies in different naturally and experimentally infected species—A review. Pathogens, 9(8), 632-633.
  4. Glass, C.M., McLean, R.G., Katz, J.B., Maehr, D.S., Cropp, C.B., Kirk, L.J., McKeirnan, A.J., and Evermann, J.F., 1994. Isolation of pseudorabies (Aujeszky’s disease) virus from a Florida panther. Journal of Wildlife Diseases, 30: 180–184.
  5. HongNa, Y., Hui, H., Hao, W., Yi, C., Han, L., and ShiFang, D., 2017. A Case of Human Viral Encephalitis Caused by Pseudorabies Virus Infection in China. Frontiers in Neurology , 10, p. 534. 
  6. Wozniakowski, G. and Samorek-Salamonowicz, E., 2015. Animal herpesviruses and their zoonotic potential for cross-species infection. Annals of Agricultural and Environmental Medicine, 22(2).
  7. Pedersen, K., Bevins, S.N., Baroch, J.A., Cumbee Jr, J.C., Chandler, S.C., Woodruff, B.S., Bigelow, T.T. and DeLiberto, T.J., 2013. Pseudorabies in feral swine in the United States, 2009–2012. Journal of wildlife diseases, 49(3), 709-713.
  8. Pejsak, Z.K. and Truszczynski, M.J., 2006. Aujeszky’s disease (pseudorabies). Diseases of Swine, Ninth Edition. Oxford, UK: Blackwell Science, pp.419-433.

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