Swine flu threat to United States is real and growing; NYT says it will take time for laboratories to determine if it's outbreak or edge of pandemic

In an ominous story just published late this evening, The New York Times describes the swine flu outbreak in Mexico and now with 20 confirmed cases in the United States as now possibly approaching the edge of a pandemic.

But we won't know for some time the size of threat due to the lack of facilities in North America to determine everything from the potency of the virus to how easily it is transmitted and who has an official case of the illness.

Reporting from Los Angeles, The Times of London sounded this ominous note about some Americans on the border being told to get painter's masks from hardware stores:

North of the border, in the US, doctors were advising people worried about the illness to buy painters’ masks from DIY stores as a precautionary measure. Authorities across the globe were torn between the imperative of slowing the spread of a potential flu pandemic and the need to avoid bringing every big city to a grinding halt.

Last night the US authorities were still allowing people to cross the border from Mexico, where it is thought that the swine flu emerged. But customs officials at the San Ysidro and Otay Mesa crossings were given protective clothing.

The New York Times reports on this fast evolving story:

Responding to what some health officials feared could be the leading edge of a global pandemic emerging from Mexico, American health officials declared a public health emergency on Sunday as 20 cases of swine flu were confirmed in this country, including eight in New York City.

Other nations imposed travel bans or made plans to quarantine air travelers as confirmed cases also appeared in Mexico and Canada and suspect cases emerged elsewhere.

Top global flu experts struggled to predict how dangerous the new A (H1N1) swine flu strain would be as it became clear that they had too little information about Mexico’s outbreak — in particular how many cases had occurred in what is thought to be a month before the outbreak was detected, and whether the virus was mutating to be more lethal, or less.

“We’re in a period in which the picture is evolving,” said Dr. Keiji Fukuda, deputy director general of the World Health Organization. “We need to know the extent to which it causes mild and serious infections.”

Without that knowledge — which is unlikely to emerge soon because only two laboratories, in Atlanta and Winnipeg, Canada, can confirm a case — his agency’s panel of experts was unwilling to raise the global pandemic alert level, even though it officially saw the outbreak as a public health emergency and opened its emergency response center.