Swine flu - influenza A (H1N1)
What is swine flu?
Swine influenza, known as swine flu or influenza A (H1N1), is a respiratory disease of pigs caused by type A influenza viruses, most commonly the H1N1 subtype. Regular outbreaks of swine flu occur in pigs year round, and cases have been transmitted to humans. Previously, human-to-human transmission of swine influenza has been limited.
| How do new swine flu viruses arise? |
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| Pigs can be hosts for several different flu viruses – swine influenza, avian (bird) influenza and human influenza. Sometimes more than one type of influenza virus can be present in a pig at the same time and this can allow genetic material from different virus types to mix, creating a new flu virus. Pigs have been known to be a potential source of new human flu viruses for a long time. The April 2009 outbreak of swine flu was caused by a new virus which has a mix of genes from human, avian and swine influenza viruses. These emerging new types of influenza virus make it difficult to create useful vaccines against them. |
What is special about the recent swine flu outbreak?
The April 2009 outbreak of swine influenza was of the H1N1 subtype and was shown to be transmitted between humans. The subtype of an influenza A virus (e.g. H1N1) is determined by the form of the haemagglutinin protein (e.g. H1) and the form of the neuraminidase protein (e.g. N1, N5) the virus carries.
Authorities (rightly) feared that this H1N1 subtype had features that may allow it to be easily passed from human to human and to cause a pandemic. Because the virus is so new, people do not generally have any immunity to it. Normally, flu viruses share some common features with the flu viruses of previous years – and so people may have a degree of resistance to them. But this new virus is different from those going before it, and so health authorities fear that people do not have any resistance to it – which gives it the potential to cause widespread infection.
The outbreak caused many deaths in Mexico, then spread to other countries. In June 2009 the World Health Organization declared that the world was at the start of the 2009 influenza pandemic.
By early November 2009 there had been over 37,000 confirmed cases of swine flu in Australia. More than 4700 people had been hospitalised and there had been 189 deaths. Normally flu infections are rare in the warmer months, but because swine flu continued to occur in the Northern Hemisphere summer, experts are concerned that infections will continue over the Australian summer, or could return in a more virulent form.
| What is a pandemic? |
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| A pandemic is an epidemic of disease that affects a wide geographic area. A famous pandemic was the Spanish flu pandemic of 1918. This was also caused by an influenza virus subtype H1N1, which spread to many parts of the world infecting an estimated half the world’s population at the time, and killing millions of people. |
What are the symptoms of swine flu?
The symptoms of swine flu are very similar to those of the human flu that we are familiar with each winter. These swine flu symptoms include: fever; cough; body aches and pains; fatigue; chills; headache; runny nose; sore throat; and respiratory distress (trouble breathing). Some people have reported diarrhoea and vomiting in association with swine flu.
| Commonwealth Health Hotline for Swine influenza |
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| If you are suffering flu-like symptoms, or if you are concerned about swine influenza, ring the Commonwealth’s national health hotline for information. Telephone: 1802007 |
What should I do if I think I have swine flu or have been in contact with someone who has swine flu?
Generally, pandemic H1N1 influenza is mild. Most people will be able to care for themselves at home and will not need to see a doctor. However, the Australian Government's Health Emergency Hotline recommends that if you have flu-like symptoms and they are becoming worse, you should seek advice by phoning your healthcare provider, hospital or the pandemic H1N1 Hotline on 180 2007.Treatment is available but it needs to be given early in the disease. It is especially important to get medical advice at the first signs of severe illness in children, and in people who have chronic medical conditions.
| State and Territory Department of Health websites |
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| WA: call 1800 186 815 or visit http://www.health.wa.gov.au/swine_flu/home |
| SA: call 1800 022 222 or visit www.flu.sa.gov.au |
| VIC: call 1300 882 008 or visit http://humanswineflu.health.vic.gov.au |
| TAS: call 1800 358 362 (1800 FLU DOC) or visit www.pandemic.tas.gov.au |
| ACT: call 02 6205 2300 or visit Government of ACT Department of Health |
| NSW: visit www.emergency.health.nsw.gov.au/swineflu/vaccination/index.asp or call 180 2007 for your local Public Health Unit contact |
| QLD: 13HEALTH (13 43 25 84) or visit www.health.qld.gov.au/swineflu/html/vacc.asp |
| NT: call 08 8922 8044 or visit www.swinefluvax.nt.gov.au |
Are there any treatments for swine flu?
There are antiviral medicines which are used to treat influenza. Two of these are available in Australia as Relenza (zanamivir) and Tamiflu (oseltamivir). They are available only on prescription from a doctor. Health authorities have recommended these 2 antivirals for use in swine influenza outbreaks. It is possible, however, as an outbreak or pandemic progresses that the virus may mutate and become resistant to these antiviral drugs.
Using antiviral medications, soon after a person is infected with flu viruses (ideally within 2 days), can inhibit the flu viruses from multiplying in a person’s body and so make the illness less severe and make the person less likely to develop serious complications.
Is there a swine flu vaccine?
Yes, pandemic flu vaccination is available as Panvax H1N1 vaccine. From September 2009, pandemic flu vaccine has been offered free to all Australians 10 years or older. In December 2009 Panvax was registered for children 6 months and older and Panvax Junior was registered for children 6 months to less than 3 years of age. The vaccine is also free for these younger age groups.
This H1N1 vaccine does not contain live virus and so cannot give you influenza. People generally start producing antibodies that provide protection against pandemic flu, 2 weeks after being vaccinated. the protection is expected to last at least a year.
What is Australia doing in response to the threatened pandemic?
The Australian Government declared swine influenza a quarantinable disease. This gives it the power to take action and prevent the spread of the disease. Early measures in Australia focussed on strengthening its border surveillance and limiting any spread of the virus within Australia. The Government is now encouraging the community to be vaccinated to protect themselves and to stop the flu spreading.
Last Reviewed: 04 December 2009
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