THE World Health Organisation (WHO) is poised to declare a global swine flu pandemic despite suggestions by scientists that the H1N1 virus responsible may be no more dangerous than the average annual flu season.

Health officials yesterday confirmed two more cases of swine flu in Britain, bringing the total to 15. A six-year-old Oxfordshire girl who had holidayed in Mexico became the youngest victim, while the second victim was the husband of a woman who contracted the virus after the couple returned from Mexico.

Meanwhile in Scotland, a man who flew from Texas to Prestwick via Birmingham last Thursday was named as a probable victim. All UK victims have so far shown mild flu-like symptoms and are recovering well.

The first case of pigs being infected with the new virus emerged last night when officials in the Canadian province of Alberta said some animals were thought to have been infected by a farm worker who had recently visited Mexico and became ill on his return.

The is this week expected to escalate the outbreak to a full pandemic — level six on its six-point scale — because of the continuing spread of swine flu among people who haven’t been to Mexico. There is concern that the virus may become resistant to drugs.

Dr Michael Ryan, WHO director of global alert and response, yesterday said there was no evidence yet of a sustained spread of the virus outside North America. He added, however, that a pandemic remained imminent. So far, 17 countries have reported 653 cases of H1N1 and 17 Mexicans have died.

Outside Mexico the virus does not appear to be severe, despite a warning last week from Dr Margaret Chan, director-general of the WHO, that a swine flu pandemic would pose a “threat against humanity”.

Alan Hay, director of the WHO’s World Influenza Centre in Mill Hill, north London, said there are signs the virus is not as virulent as first feared. Experts believe it may be comparable to seasonal flu, which kills up to 12,000 a year in Britain, and 550,000 worldwide.

Hay said: “This might not be any more virulent than normal seasonal flu infections. We feel reassured that if this develops into a pandemic it might not be a particularly severe one.”

Scientists are encouraged by initial analyses of the DNA sequence of the virus, which has found it lacks the traits that led to the death of nearly 50m people in the 1918 Spanish flu outbreak.

A senior consultant who has been treating swine flu victims said: “The way they are talking you would think our culture is collapsing. This time last week we were all incredibly worried because the reports from Mexico were that hospitals were full and people were dying all over the place.

“Actually it doesn’t seem to be that severe. The symptoms are unpleasant — fevers, shivering, aches — but no worse than normal seasonal flu. Our patient made a full recovery.”

The WHO will upgrade its alert level to phase six if the virus is passed successively between three unrelated people on two continents. This has occurred in Mexico and the US, and there have been two cases of transmission between two unrelated people in the UK. One involved Barry Greatorex, 43, who contracted H1N1 after a 30-minute meeting with a colleague in Leicestershire. As a result, the WHO says it may declare a pandemic in days.

Dr Nikki Shindo, a WHO medical health officer, said the biggest concern was that the virus could mutate and become resistant to Tamiflu, the anti-viral drug. Britain has stockpiled 23m courses of Tamiflu and last week ordered 15m more, but the Centers for Disease Control in Atlanta, Georgia, says 98% of existing H1 flu strains were resistant to Tamiflu in the last flu season. Scientists are struggling to understand why this is.

Shindo said: “The worst-case scenario is the virus will mutate and become Tamiflu-resistant. The best-case scenario is that it causes only mild illness and continues to respond to Tamiflu.”

In Mexico, the government has revised the suspected swine flu death toll from 176 to 101, suggesting the outbreak is not as bad as was feared. The WHO has only confirmed 16 deaths in Mexico to date, plus a Mexican child in Texas.

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