Global alarm at swine flu outbreak

"It has pandemic potential," Margaret Chan, the director general of the World Health Organization, told reporters during a telephone briefing. "In the assessment of WHO this is a serious situation that must be watched very carefully."

Chan held the briefing after cutting short a trip to the United States so she could rush back to the WHO's headquarters in Geneva to convene an emergency meeting of specialists to decide what steps should be taken to contain the virus. It is the first time the committee has been called upon since it was created two years ago to handle disease outbreaks.

The new swine flu strain has killed as many as 81 and sickened possibly 1,300 more in Mexico. It first spread outside Mexico to Texas and California, where there have been at least eight reported nonfatal cases. Yesterday, two new cases were reported in Kansas, and there was a suspected outbreak in New York City, where the health commissioner, Thomas Frieden, said tests showed that eight high school students had an influenza virus that was "probable" swine flu.

Samples were sent to the US Centers for Disease Control and Prevention for further testing to see whether they are the same rare strain.

The New York students reported only mild symptoms and are recovering well.

There were no reported cases in Massachusetts as of last night, and state officials specifically disputed an NBC news report suggesting there were. Indeed, flu cases of all kinds had begun to ebb here with the end of the traditional flu season. A statewide network of about 30 medical practices that act as bellwethers for flu activity has reported a drop-off in cases in recent weeks, said Dr. Alfred DeMaria, the state's top disease tracker.

"But prudence would dictate to watch this extremely closely, because it's a newish influenza strain," DeMaria said.

The Boston Public Health Commission also has a system that yields a daily report on traffic in hospital emergency rooms, and that network has detected no uptick in cases, said Dr. Anita Barry of the city agency.

Early this week, Boston doctors will receive an alert from the city health department telling them to get nose and throat samples from patients stricken with influenza symptoms who say they have recently traveled to the parts of California and Texas where swine flu has been reported, Barry said.

"I'm concerned enough that we're going to follow this very, very closely," Barry said. "And as part of our routine surveillance, we're going to pay particular attention to anything that suggests we're seeing increased influenza activity."

The state has no immediate plans, DeMaria said, to activate measures designed to free up hospital beds for flu patients, such as canceling elective surgeries. That would happen, he said, only if there is evidence that the virus has spread to New England.

"Your response has to be measured to the threat," DeMaria said. "You don't endanger other people's health by doing these things prematurely."

In Mexico, the government has taken steps to try to control the outbreak, which has struck hardest in the sprawling capital, Mexico City. Thousands of public events have been canceled, and school suspended for millions of students. But despite the government efforts, alarm has continued to grow, and yesterday another 24 suspected cases of the flu were reported in the city, according to the Associated Press.

Meanwhile, at the WHO, officials could recommend the declaration of an international public health emergency, which could have major implications on travel and trade. It could also raise its "pandemic alert level," currently at level three. That level means there is a very limited spread of virus from person to person.

"The situation is evolving quickly," Chan said. "We do not yet have a complete picture of the epidemiology or the risk, including possible spread beyond the currently affected areas."

The new strain contains gene sequences from North American and Eurasian swine flu viruses, North American bird flu, and North American human flu, said the CDC.

One additional source of alarm is that most of Mexico's dead thus far have been young, healthy adults, and none were over 60 or under 3 years old, the World Health Organization said.

That alarms health officials because seasonal influenzas cause most of their deaths among infants and bedridden elderly people, but pandemic influenzas like the 1918 Spanish flu and the 1957 and 1968 pandemics often strike young, healthy people the hardest.

Material from Globe wire services was used in this report.