Pandemic influenza

Last updated: 07 February 2008

What is avian influenza (bird flu)?

Avian influenza is an infectious disease of birds, caused by a number of different strains of avian influenza virus. Usually the virus circulates in wild bird populations causing no disease or only mild disease. Infection of domestic poultry, such as chickens, can cause severe disease in these birds. There are a number of different strains of avian influenza, only a few of which can cause disease in humans.

A new type of avian influenza, called influenza A H5N1, was first recognised in 1997 in Hong Kong. This strain reappeared in late 2003 and has rapidly spread to many Asian, Middle-Eastern, European and African countries, causing severe infection in wild birds and domestic poultry locks. There is no evidence that H5N1 influenza is currently infecting birds or humans in Australia.

What is pandemic influenza?

A large-scale, worldwide human influenza epidemic is called a pandemic. Pandemics occur when a new virus emerges to which people have little or no immunity. Previous influenza pandemics occurred in 1918-19, 1957-58 and 1968-69. In the 1918-19 pandemic, between 20 and 40 million people died. Many scientists are concerned that the recent H5N1 outbreak in birds could mutate to produce a new strain of influenza virus that spreads easily between people, resulting in a pandemic.

What are the symptoms?

A pandemic strain of influenza does not currently exist anywhere in the world. The symptoms of the next pandemic are difficult to predict, as different strains of influenza can lead to different symptoms in people. However, influenza strains usually cause symptoms typical of normal seasonal human influenza (fever, cough, tiredness, muscle aches, sore throat, shortness of breath, runny nose, headache). In some cases, influenza can result in a severe pneumonia and, in a small number of cases, encephalitis (inflammation of the brain) or diarrhoea. Symptoms of influenza generally appear between two to four days following exposure.

Who is at risk?

People at risk of becoming infected with a pandemic influenza strain are those that have been in close contact (usually within 1 metre) of a person infected with the new influenza strain. People who live in the same house as someone with pandemic influenza, and people that look after someone while they are ill, are most at risk of becoming infected.

How is it prevented?

As a pandemic influenza stain has not yet developed, a human vaccine for pandemic influenza is not yet available. Existing vaccines for normal human influenza will not provide protection against pandemic influenza. Scientists worldwide are currently working to develop a suitable vaccine for a pandemic influenza strain.
 
Until a vaccine becomes available, the best method of prevention is to ensure that everyone washes their hands regularly and thoroughly, makes sure that they don't cough or sneeze into other people's faces, and that they cough or sneeze into tissues. After coughing or sneezing, people should dispose of their tissues immediately, and wash their hands with soap and water. People who may have pandemic influenza should stay at home until they are completely better.

People with pandemic influenza should wear a mask to help to prevent spreading the infection to other people in the house. People looking after other people who are sick should wear full personal protective equipment, including goggles, gloves, masks and protective clothing, and, if necessary, should take anti-influenza medication.

How is it diagnosed?

Pandemic influenza virus infection can be diagnosed using specimens of blood, or from swabs of the nose and throat. Testing is done at a specialised laboratory.

How is it treated?

Specific anti-influenza drugs are likely to be effective against pandemic influenza in humans. If you become unwell and suspect that you may have pandemic influenza, you should go to your nearest hospital emergency department or influenza clinic for assessment and treatment.

What is the public health response?

Outbreaks of different strains of pandemic influenza have occurred previously in Australia. However, there have been no recent reports of pandemic influenza anywhere in the world. Human infection with pandemic influenza must be notified to the local public health unit. Should suspected human cases occur in NSW, the local public health unit would work with the patient, the treating doctors, and the laboratory to confirm the diagnosis. Suspected cases would be isolated from others to prevent further infections. Close contacts of these cases who may have been exposed to the virus will be given information about the risk of infection. Should these people also develop symptoms, they would also be isolated and tested for pandemic influenza.

Travel advice

Australians should not travel to areas affected by pandemic influenza.

For more information

Australian Government Department of Health and Ageing information hotline 1800 004 599

Other information

• Pandemic Preparedness  /PublicHealth/Pandemic/index.asp
• Australian Government Department of Health and Ageing - Pandemic Influenza  http://www.health.gov.au/internet/main/publishing.nsf/Content/ohp-pandemic-ahmppi.htm