With open air travel a common occurrence,
global health bodies warn that swine flu
can cross borders easily.
Image: iStockphoto
'Swine' influenza is a contagious respiratory disease caused by influenza type A, which infects pigs or swines. Until now, similar strains have not infected humans, but this strain is spread between people by coughing and sneezing.
The latest strain is described as a reassortment of several strains of influenza A virus that are, separately, endemic in humans and swine (pigs). There is no evidence it causes disease in pigs or people who eat pork.
Its origins are unknown. One theory is Asian and European strains travelled to Mexico in migratory birds or in people.
The classical swine flu virus was first isolated from a pig in 1930.
Influenza viruses bind through the surfaces of epithelial cells, typically in the nose, throat and lungs of mammals and intestines of birds.
Can it be stopped?
According to experts, it is unlikely in a world of frequent flyers.
The World Health Organisation says restricting flights or closing off borders will achieve little.
WHO deputy chief Keiji Fukuda says the virus cannot be contained and countries should focus on mitigating its effects. United Nations scientists are currently moving to inspect sites in Mexico, including industrial pig farms, to find the source of the latest viral outbreak.
The US, Canada, Britain and Israel have confirmed cases, with Spain reporting one death.
The Australian Government has stockpiled 8.7 million doses of the Tamiflu and Relenza drugs, which appear to be effective in treating the virus.
The Federal Government also has strengthened border surveillance measures at airports. Staff with the Australian Quarantine and Inspection Service will assess people with flu-like symptoms and decide whether further medical attention is required.
Flight crews will make onboard announcements as people arrive in the country.
WA’s chief health officer Tarun Weeramanthri said emergency departments and GPs are being kept up to date about the swine flu virus.
The Health Department cleared three out of 10 people suspected of having the virus when they stepped off a plane on Tuesday this week. The rest have been sent home with masks.
Dr Weeramanthri says experts have had six years since the SARS outbreak to tighten up health responses to potential pandemics.
The Chinese SARS outbreak spread to 37 countries - from November 2002 up to July the following year. Out of more than 8000 cases, 774 people died, according to WHO.
Dr Weeramanthri said WA was still in the alert phase for swine flu.
The Australian Commonwealth swine influenza hotline is 1802007.
A history of influenza pandemics
1918: The Spanish flu pandemic was caused by a H1N1 flu strain. Tens of millions died.
1957: Asian flu killed two million people. Caused by a human form of the virus, H2N2, combined with a mutated strain found in wild ducks.
1968: An outbreak first detected in Hong Kong, and caused by a strain known as H3N2, killed up to one million people globally.
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