Samples from suspected flu cases are being sent to the Centers for Disease Control and Prevention in Atlanta for analysis. Scott Bryan, a media relations worker for the Centers for Disease Control in Atlanta, said Friday there have been no confirmed cases of swine flu in Alabama.
State Health Officer Don Williamson said a student at Heritage Elementary School in Madison near Huntsville had been diagnosed with a probable case of the illness. Two 6-year-old kindergarten students at Heritage were diagnosed with probable cases on Wednesday.
Williamson said there is no evidence that the illness has spread to other schools in the Huntsville area.
A Montgomery woman in her 20s has also been diagnosed with a probable case.
Williamson said none of the cases appear to be any more severe than regular flu cases seen every year. The four people are recovering at home.
Williamson said at a news conference Friday that so far the health department had analyzed 200 samples in the last 48 hours, including 130 on Friday. He said the state hopes to be able to do its own tests to confirm cases of swine flu by early next week.
All high school athletic events in Alabama have been postponed through the weekend, several schools in Madison County have been closed and a range of other events, gatherings and trips have been scrubbed.
They include a party first lady Patsy Riley was to host Sunday for foster children at Wynfield Plantation in Montgomery. The event, called the "Big Birthday Party," will be rescheduled. Buses carrying members of two high school bands were turned around while on the way to a band competition at Sea World near Orlando.
Many other events across the state are going on as scheduled this weekend.
The federal government issued new guidance for schools with confirmed cases, saying they should close for at least 14 days because children can be contagious for seven to 10 days from when they get sick.
The Education Department said that 433 schools had closed nationwide, affecting 245,000 children in 17 states.
Major U.S. airlines, meanwhile, announced plans to curtail flights into flu-ravaged Mexico.
The swine flu outbreak that has alarmed the world for a week now appears less ominous, with the virus showing little staying power in the hardest-hit cities and scientists suggesting it lacks the genetic fortitude of past killer bugs.
President Barack Obama said efforts were focused on identifying people who have the flu, getting medical help to the right places and providing clear advice to state and local officials and the public.
The president also said the U.S. government is working to produce a vaccine down the road, developing clear guidelines for school closings and trying to ensure businesses cooperate with workers who run out of sick leave.
He pointed out that regular seasonal flus kill about 36,000 people in the United States in an average year and send 200,000 to the hospital.
In New York City, which has the most confirmed swine flu cases in the U.S. with 49, swine flu has not spread far beyond cases linked to one Catholic school. In Mexico, the epicenter of the outbreak, very few relatives of flu victims seem to have caught it.
A flu expert said he sees no reason to believe the virus is particularly lethal. And a federal scientist said the germ's genetic makeup lacks some traits seen in the deadly 1918 flu pandemic strain and the more recent killer bird flu.
Still, it was too soon to be certain what the swine flu virus will do. Experts say the only wise course is to prepare for the worst. But in a world that's been rattled by the specter of a global pandemic, glimmers of hope were more than welcome Friday.
New York officials said after a week of monitoring the disease that the city's outbreak gives little sign of spreading beyond a few pockets or getting more dangerous.
All but two of the city's confirmed cases so far involve people associated with the high school where the local outbreak began and where several students had recently returned from Mexico.
More than 1,000 students, parents and faculty there reported flu symptoms over just a few days last month. But since then, only a handful of new infections have been reported — only eight students since last Sunday.
Almost everyone who became ill before then are either recovering or already well. The school, which was closed this past week, is scheduled to reopen Monday. No new confirmed cases were identified in the city on Friday, and Mayor Michael Bloomberg said the outbreak in New York had so far proved to be "a relatively minor annoyance."
In Mexico, where swine flu has killed at least 15 people and the confirmed case count has surpassed 300, the health secretary said few of the relatives of 86 suspected swine flu patients had caught the virus. Only four of the 219 relatives surveyed turned up as probable cases.
The U.S. case count rose to 155 on Friday, based on federal and state counts, although state laboratory operators believe the number is higher because they are not testing all suspected cases.
Worldwide, the total confirmed cases neared 600, although that number is also believed to be much larger. Besides the U.S. and Mexico, the virus has been detected in Canada, New Zealand, China, Israel and eight European nations.
Health authorities in South Korea said today they have confirmed the country's first case of swine flu in a woman who recently returned from Mexico.
Scientists looking closely at the H1N1 virus itself have found some encouraging news, said Nancy Cox, flu chief at the federal Centers for Disease Control and Prevention. Its genetic makeup doesn't show specific traits that showed up in the 1918 pandemic virus, which killed about 40 million to 50 million people worldwide.
"However, we know that there is a great deal that we do not understand about the virulence of the 1918 virus or other influenza viruses" that caused serious illnesses, Cox said. "So we are continuing to learn."
She told The Associated Press that the swine flu virus also lacked genetic traits associated with the virulence of the bird flu virus, which grabbed headlines a few years ago and has killed 250 people, mostly in Asia.
Researchers will get a better idea of how dangerous this virus is over the next week to 10 days, said Peter Palese, a leading flu researcher with Mount Sinai Medical School in New York.
So far in the United States, he said, the virus appears to look and behave like the garden-variety flus that strike every winter. "There is no real reason to believe this is a more serious strain," he said.
Palese said many adults probably have immune systems primed to handle the virus because it is so similar to another common flu strain.
As for why the illness has predominantly affected children and teenagers in New York, Palese said older people probably have more antibodies from exposure to similar types of flu that help them fight off infection.
"The virus is so close," he said.
In the United States, most of the people with swine flu have been treated at home. Only nine people are known to have ended up in the hospital, though officials suspect there are more.