Don't panic because there's a pandemic!

The World Health Organisation (WHO) has officially raised the level of the swine flu alert to 6 - the highest level - and declared the outbreak a pandemic following an emergency meeting.

This means the swine flu virus is spreading in at least two regions of the world with rising cases being seen in the UK, Australia, Japan and Chile but Dr. Margaret Chan, the Director General of WHO says this does not mean the virus was causing more severe illness or more deaths.

The WHO says in its latest update, #47, that as of the 11th of June 2009 the influenza A H1N1 (swine flu) outbreak has now affected 74 countries with 28,774 officially reported cases including 144 deaths.

This is the first time in forty years that the WHO has declared a global flu pandemic and the soaring number of swine flu cases occurring in the Southern Hemisphere winter, particularly in Australia and in Chile, triggered the emergency meeting of the WHO and has influenced that decision - the last pandemic in 1968, the Hong Kong flu, killed about one million people.

In the last week the number of swine flu cases in Australia has tripled to over 1,300.

Hong Kong has become the latest victim with 12 students at one school contracting the virus and as a precaution health authorities have ordered 500,000 students to stay at home.

Dr. Chan says countries where outbreaks appear to have peaked should prepare for a second wave of infection but a sudden and dramatic jump in the number of severe and fatal infections is not expected.

The WHO says phase 6 does not mean anything concerning severity but indicates the extent of the geographic spread and the virus is not targeting older people, but instead it is the young under the age of 25 that are predominantly falling ill with the disease.

Experts say older people particularly those over 60 appear to be immune which suggests that they have experienced a related virus back in the 50s or earlier.

A vaccine is expected to be available within a few months towards the end of the Australian winter - Federal Health Minister Nicola Roxon says Australia's pandemic emergency committee will meet today to consider the country's handling of the global swine flu outbreak since its classification as a pandemic but it is unlikely much will change in the short term and it is likely that quarantine measures will be abandoned as the disease spreads.

Scientists say however that the new H1N1 virus responsible for the first pandemic of the 21st century, appears to have been circulating undetected among pigs for years and although health officials have been on the alert for any new influenza viruses in humans, animal health regulators have not been checking pigs.

Researchers examining the genetic sequence of the new H1N1 swine flu virus say it is a mixture of other viruses that had been circulating in pigs, one of which was itself a mixture including swine, human and avian-like genetic sequences.

Researchers Andrew Rambaut of the University of Edinburgh, Oliver Pybus of Oxford University, and Yi Guan of the University of Hong Kong, say the virus originated from several viruses circulating in swine, and they believe the initial transmission to humans occurred several months before the outbreak was recognised.

The researchers say the movement of live pigs between Eurasia and North America appears to have facilitated the mixing of diverse swine influenza viruses, leading to the new H1N1 strain and that the closest related swine viruses existed up to 17 years ago and may have been circulating in pigs for several years before it's emergence in humans.

The U.S. Agriculture Department now says it will initiate a pilot surveillance project to look for new strains of flu virus in pigs.

Dr. Chan says it is important to get the right balance between complacency and vigilance and that pandemic strategies would vary between countries depending on their specific situation - the WHO does not recommend closure of borders or any restrictions on the movement of people, goods or services.

Some experts have warned that the consequences of the virus could be more serious in the developing world and poorer nations, especially those in the southern hemisphere now heading into their winter season, face the greatest risk from the flu pandemic - there is concern that the virus might mutate in the southern hemisphere over its winter and become more virulent.

Swine flu symptoms are usually similar to seasonal flu and the best protection is to exercise good personal hygiene, such as the washing hands thoroughly, covering the nose when sneezing and the immediate disposal of used handkerchiefs. People who are infected should stay home and avoid mixing with others.