Pig flu may strike 40% of Britons

As the deadly infection carried on its relentless global rampage, with cases confirmed in seven countries and suspected cases in a further five, the death toll in Mexico soared to 152, with another 2,000 victims sick.

Professor Neil Ferguson, a member of the World Health Organisation task force, said 40 per cent of people in the UK could be infected within the next six months if the country was hit by a pandemic.

The news came as a woman was admitted to hospital with flu-like symptoms. She had recently returned home to Isleworth, Middlesex, from a trip to Mexico.

The World Health Organisation has raised its alert to stage four – a “significant increase in risk of a pandemic” – but is likely to raise this to its top level of six within a few weeks.

Prof Ferguson, of Imperial College London, said: “We don’t really know what size epidemic we will get over the next couple of months.

“It is almost certain that, even if it does fade away in the next few weeks – which it might – we will get a seasonal epidemic in the autumn.

“We might expect up to 30 to 40 per cent of the population to become ill in the next six months if this truly turns into a pandemic.

“We could get substantial numbers infected in the next few weeks but, if I was to be a betting man, I would say it would be slightly longer because we are moving into summer.”

Prof Ferguson said the 152 deaths in Mexico probably made up a relatively small proportion of the total number infected, which might run into tens or hundreds of thousands.

His warning came as the World Health Influenza Centre warned that since people die in the UK from influenza every year “it is inevitable someone in the UK will die from swine flu”.

The UK Government’s chief medical adviser, Professor Sir Liam Donaldson, has said there are only enough anti-viral drugs to treat half the population.

He admitted: “We are very concerned. It does seem as if this disease is a new strain of flu, one that is spreading quite rapidly.”

As dozens of people were tested, health officials said many of the suspected cases were likely to be negative. Dr Maureen Baker, honorary secretary of the Royal College of GPs, urged family doctors to reassure patients that they could expect to recover from flu within a week, even if it was swine flu.

Prime Minister Gordon Brown said Britain was “among the best- prepared countries in the world”.

He added that the Government was taking “all the urgent action that is necessary” to help prevent the spread of the virus.

The Government’s Cobra emergencies committee, involving Mr Brown and Health Secretary Alan Johnson, met to discuss the issue as Britons were warned to avoid all but essential travel to Mexico.

The European Commission warned that outbreaks were likely to get worse in Europe over the next few days but advised the public not to panic.

EU Health Commissioner Androulla Vasiliou said there were still only four confirmed cases in the EU – two in Spain and two in the UK.

However, there are suspected cases in Germany, Italy, Sweden, Greece and the Czech Republic.

The virus, which is caused when the H1N1 strain associated with pigs crosses over to the human population, has also been confirmed in the United States, Canada, Spain, New Zealand and Israel.

In the US, the number of cases rose to 64, including 28 at a single New York school.

Other US cases have been reported in Ohio, Kansas, Texas and California.

Eleven cases were confirmed in New Zealand, 13 in Canada, two in Spain and two in Israel.

None of the cases outside Mexico has been fatal.

Meanwhile, shares in holiday companies saw a second day of losses as fears over the spread of the virus kept world markets under pressure.