Swine influenza


Swine influenza is category 1 (for H1N1 strain) restricted matter or prohibited matter (for all other strains) under the Biosecurity Act 2014.

Under Queensland legislation, if you suspect the presence of this disease in pigs, you must report it to Biosecurity Queensland on 13 25 23 or contact the Emergency Disease Watch Hotline on 1800 675 888.

Swine influenza is a highly contagious acute respiratory disease of pigs.

Influenza viruses describe a large group of viruses that are classified as type A, B or C. Within this large group, different influenza viruses infect different species of animals, and humans. Influenza viruses are usually 'specialised' to infect only one species of animal, although occasional cross-infection to other species can occur. The swine influenza viruses belong to type A.


Swine influenza occurs in most areas of the world where pigs are kept.

Life cycle

Infection can also occur with no clinical syndrome evident. Mortality is generally low (1-3%) and, in the absence of complications, most affected pigs will recover in 5-7 days.

In Australia, these signs would be obvious, as the Australian pig herd has little immunity against swine influenza and would be susceptible to the disease.

Affected animals

  • pigs
  • humans


In the Australian herd, the disease would typically be expected to manifest as a sudden onset in pigs of any age:

  • pigs going off feed
  • sudden onset high fever
  • weight loss or anorexia
  • discharge from eyes and nose, sneezing
  • breathing difficulties and a barking cough
  • huddling and inactivity.


In general with swine influenza, a large number of pigs are likely to be affected (up to 100%) but only a small number are likely to die (1-3%).

How it is spread

This is a herd disease, with a large number of pigs in a herd affected.

The virus is primarily transmitted among pigs in close contact through nasal discharge and aerosols from sneezing and coughing. The main method of spread is through the movement of infected pigs.

The virus may also be spread from contaminated objects moving between infected and uninfected pigs. Influenza A viruses can infect a wide variety of animal species, including humans.

While it is recognised that swine influenza viruses do not usually infect humans, rare human infections have occurred. Similarly, it is well recognised that influenza viruses may be spread from humans to pigs.

People working in piggeries and those having frequent contact with pigs should consider personal influenza vaccination, while remaining attentive to appropriate personal hygiene and biosecurity practices.

Risk period

Outbreaks in pigs can occur year round, with an increased incidence in the colder months in temperate zones.

Monitoring and action

Anyone who is in contact with pigs and experiences flu-like symptoms should contact their local doctor or Queensland Health population health unit, or call 13 HEALTH (13 43 25 84).


Protecting your farm

To help prevent diseases on your farm:

  • enforce good on-farm biosecurity procedures
  • update property biosecurity plans by checking the Biosecurity Queensland and Australian Pork Limited websites to get further information about suitable farm biosecurity procedures
  • be vigilant with disinfection and cleaning when people enter and leave the farm.

Government response to swine influenza in Australia

The detection of swine influenza in Australia is regarded as a significant risk to pig health and productivity, and a potential risk to human health. In the event of an outbreak, every effort will be made to contain the spread of swine influenza until the outbreak dies out or has been eradicated, if feasible. National arrangements are already in place to support such a response.


Biosecurity Queensland will work with affected owners to manage the disease in affected piggeries according to an agreed national response policy.

Strict biosecurity controls will be applied to contain the disease and prevent its spread to other pigs, to other farms with pigs, and to humans working with infected pigs.

If a swine influenza incident is considered not able to be contained or eradicated within an acceptable time period (e.g. pandemic H1N1), government will support industry to protect animal health and welfare, worker health and safety, and market access.

Farmers with pigs will be reminded to remain vigilant with regard to their biosecurity and notification obligations.

In other countries, pigs are routinely vaccinated against swine influenza, but the vaccine is not registered for use in Australia.

Further information