Pseudorabies

What is pseudorabies?

Pseudorabies, also known as Aujeszky's disease, is a viral disease causing neurological and respiratory disease in swine, which are the natural hosts of the virus.

It sporadically infects other species (cattle, sheep, goats, dogs, cats, mink, foxes, raccoons and rats), causing a fatal neurological disease with rabies-like signs and severe itching. Another name for the disease in cattle is "mad itch".

Is pseudorabies a risk to human health?

No. There is no human health risk associated with pseudorabies.

What are the clinical signs of pseudorabies?

Swine show different signs of the virus depending on age, with the youngest animals being the most severely affected:

• Neonates/suckling pigs: In very young pigs, the only sign may be an inability to move or stand up; they may sit like dogs due to posterior paralysis. Slightly older piglets may have a fever, loss of appetite, vomiting and nervous system signs such as incoordination, drowsiness, muscle twitching, convulsions and paralysis. Mortality in suckling pigs is close to 100 per cent.
• Weaner pigs: The mortality rate is lower (five to 10 per cent). The clinical signs may resemble those in utero, neonates, and suckling pigs but respiratory signs including coughing, sneezing and laboured breathing, are more prominent.
• Grower and finisher pigs: Respiratory disease is the most common sign. Mortality rates are low (one to two per cent).
• Adult pigs: Infection in adult pigs is often mild or unapparent. Gilts and sows may have reproductive problems, such as early embryonic mortality, abortion, mummified fetuses, stillbirths or they could give birth to weak and trembling pigs who quickly die.

Infections in species other than pigs are almost always fatal. Symptoms may include intense itching, scratching and self mutilation, an inability to rise, incoordination, paralysis and rapid death.

Where is pseudorabies found?

Pseudorabies has been reported in most countries, with the exception of Canada, Greenland, Australia and any African country.

The U.S. has been actively working towards eradication of the disease since 1989, and by 2004, domestic swine in all states were considered free of the virus. However, the pseudorabies virus is known to be present in feral swine and these animals pose an on-going risk to the domestic population.

How is pseudorabies transmitted and spread?

Pseudorabies is highly contagious in pigs and the disease will spread rapidly throughout an entire herd. The virus is spread mainly via the respiratory route and nose-to-nose contact. Piglets can become infected in utero and through milk from an infected sow.

Pseudorabies is a herpes virus; once an animal is infected, it remains infected for life and it may not demonstrate any signs of disease even though it is shedding the virus.

Transmission can also occur by contaminated drinking water, coming in contact with contaminated clothing, footwear, or equipment, especially in cool, damp weather which helps virus survival. There is evidence of airborne transmission.

How is pseudorabies diagnosed?

Laboratory testing is done on tissue and blood samples to detect the virus and its antibodies.

How is pseudorabies treated?

There is no specific treatment for the disease. Vaccination can prevent illness and alleviate clinical signs in acute cases, and it is used extensively in some countries to control the disease. In the U.S., vaccination is part of the pseudorabies eradication program.

What is done to protect Canadian livestock from pseudorabies?

The Canadian Food Inspection Agency (CFIA) imposes strict regulations on the import of animals and animal products from countries where pseudorabies is known to occur. These regulations are enforced through port-of-entry inspections done either by the Canada Border Services Agency or the CFIA.

Pseudorabies is a "reportable disease" under the Health of Animals Act. This means that all suspected cases must be reported to the CFIA for immediate investigation by inspectors.

How would the CFIA respond to an outbreak of pseudorabies in Canada?

Canada's emergency response strategy to an outbreak of pseudorabies would be to:

• eradicate the disease; and
• re-establish Canada's disease-free status as quickly as possible.

In an effort to eradicate pseudorabies, the CFIA would use its "stamping out" policy, which includes:

• the humane destruction of all infected and exposed animals;
• surveillance and tracing of potentially infected or exposed animals;
• strict quarantine and animal movement controls to prevent spread;
• strict decontamination of infected premises; and
• zoning to define infected and disease-free areas.

Owners whose animals are ordered destroyed may be eligible for compensation.

For more information

Contact your CFIA Area office:

Atlantic Area: 506-851-7651

Quebec Area: 514-283-8888

Ontario Area: 519-837-9400

Western Area: 403-292-4301

You can find your local CFIA District office on the CFIA Web site or by consulting the blue pages of your local phone directory.