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LONDON - Flu experts are looking very closely at Britain and some have decided that the U.K.'s H1N1 flu-fighting tactics are seriously off the mark and may be hiding a much larger outbreak.

Since Britain has the most confirmed swine flu cases in Europe, how the outbreak develops here will have a significant influence on whether the World Health Organization decides to raise its flu alert to the highest level: a pandemic, or global epidemic.

British authorities have relied on an aggressive strategy to try to snuff out the virus before it spreads, blanketing suspect cases and anyone connected to them with the antiviral medication Tamiflu.

But experts criticize the strategy for wasting valuable medicine and say there's little point trying to contain swine flu, which is more infectious than regular flu.

"Containment using Tamiflu is a flawed concept," said Michael Osterholm, a flu expert at the University of Minnesota. "It's like trying to maintain the integrity of your submarine with screen doors."

Osterholm, who has advised U.S. authorities on preparing for a pandemic, said the swine flu virus travels too fast to stop it with Tamiflu.

"You are never going to contain a flu virus with this strategy and at the end of it all, you will have wasted time and drugs," he said, because it takes much more Tamiflu to prevent a case than it does to treat one.

Similar strategies were initially tried in the United States, Canada and Japan but authorities quickly dumped the tactic. Japanese officials had hoped to contain their outbreak, but now say they probably can't, as confirmed cases soared from four to more than 260 in just a week.

Authorities in Mexico never even tried to contain the virus, it was too widespread before they realized what it was.

Swine flu has sickened more than 11,000 people in 41 countries and killed 85, according to WHO, whose figures often trail those of individual countries. Mexico has reported 75 confirmed swine flu deaths, the United States 10, and there has been one confirmed death each in Canada and Costa Rica.

British health officials have confirmed 112 swine flu cases - the most in Europe, ahead of Spain, which raised its total to 111 on Thursday. Still, that number has raised eyebrows among experts for being suspiciously low, given swine flu's infectiousness and its rapid spread elsewhere.

Rumours have swirled among health officials for weeks that Britain's caseload is far higher than officials are admitting.

"It's odd that we haven't seen more cases in Britain after the initial burst of cases," said Andrew Pekosz, a flu expert at Johns Hopkins University in Baltimore.

Osterholm called Britain's official numbers "meaningless" and said while authorities were not hiding cases, they also weren't looking very hard for the virus.

"The numbers in Britain are really not telling the story," Osterholm said.

Swine flu was first detected in Britain last month. Experts say flu viruses only need a couple of weeks to become established in a new location.

Albert Osterhaus, a virologist at Erasmus MC University in the Netherlands, said once the virus has been circulating, it's time to abandon the containment strategy and save Tamiflu for patients.

Experts said Britain's attempt to squash swine flu might also be masking the true size of the outbreak. Antivirals like Tamiflu work by reducing the amount of virus in a person's body, so people who have swine flu and are taking Tamiflu might test negative for the virus.

"Using Tamiflu to contain a virus may nip (an outbreak) in the bud ... but you might also pick up fewer cases," said Osterhaus.

Still, Britain's Health Protection Agency defended its methods.

"We are still in the early phases of the swine flu outbreak," a spokesman said, speaking on condition of anonymity in line with official government policy. "We believe containment is still an effective strategy but we will certainly reconsider it if swine flu spreads."

Pekosz said the low numbers of confirmed cases in Britain could also be due to limited testing.

The U.S. Centers for Disease Control and Prevention is testing up to 400 specimens a day, but the British health agency has refused to say how many tests are being done daily. The U.K. is also only testing people with a history of visiting infected countries like Mexico or the United States, or people with links to already-established cases. That limited criteria means authorities could be missing lots of other cases if the virus has already spread into communities.

"There's no reason to think this virus would behave differently in Europe than in North America," Pekosz said. "The numbers in the U.S. and Mexico suggest that once you have a certain number of cases, you can seed a relatively wide outbreak."

For its part, Spain is taking much the same tactic as Britain. Health authorities have started announcing new swine flu cases only once a week and are handing out antiviral drugs to both confirmed and suspected cases.

Countries outside of North America may be reluctant to admit they have a bigger outbreak on their hands, since that could prompt WHO to declare a pandemic.

Many governments fear that announcing a pandemic would produce mass panic and confusion, with citizens clamouring for measures - including vaccines, antiviral medications, trade restrictions and travel bans - that could be costly or even ineffective.

On Monday, British Health Secretary Alan Johnson urged WHO to raise its standards for determining a pandemic.

For now, British authorities say they are still trying to contain swine flu with Tamiflu and have no plans to change who they test.

Experts remained skeptical.

"If there really are that few cases in Europe, we should all be sending teams there to find out what is going on," Osterholm said.