I don't know why people are so determined to ignore this. As someone who's had pneumonia, trust me, it's not an experience you want to have. I was lucky enough to have a bacterial strain that responded to antibiotics. Please, see a doctor if you have any doubts:

The World Health Organization urged doctors Friday to treat suspected swine flu cases as quickly as possible with antiviral drugs, warning that the virus can cause potentially life-threatening viral pneumonia much more commonly than the typical flu, sometimes in relatively young, otherwise healthy people.

"It's not like seasonal influenza," said Nikki Shindo, a medical officer in the WHO's Epidemic and Pandemic Alert and Response Department. "It can cause very severe disease in previously healthy young adults."

Shindo's comments came at the conclusion of a special three-day meeting in Washington of more than 100 experts from around the world. The WHO called the meeting to review the latest research on the new H1N1 virus and to revise guidelines for treating the infection.

Unlike the seasonal flu, Shindo said, the virus appears more likely to travel deep into the lungs, where it can cause viral pneumonia. Such a condition can cause severe lung damage and a life-threatening condition known as acute respiratory distress syndrome.

"Remarkably different is this small subset of patients that presents very severe viral pneumonia," Shindo said.

Shindo noted that some hospitals in Australia and New Zealand were severely strained by seriously ill swine flu patients during their recently ended winter.

"This disease overwhelmed emergency rooms and especially intensive care units because of the very severe patients that required special care," Shindo said, urging hospitals to prepare for the possibility of a significant number of patients requiring intensive care.

"We can expect more severe disease during the upcoming influenza season," she said.

Shindo noted that, although a few cases have been reported of people who have been infected with virus that is resistant to antiviral drugs, the medications remain highly effective for most patients if administered quickly.

"Do not delay treatment," Shindo said. "Do not miss this opportunity for early treatment."

The WHO's warnings came as U.S. health officials announced that the number of states reporting widespread flu had increased from 37 to 41 and regional or local outbreaks were being reported in the remaining parts of the country.

The number of deaths from pneumonia and flu-like illnesses had surpassed what the CDC considers an epidemic level, said Anne Schuchat of the federal Centers for Disease Control and Prevention. About 6 percent of all doctor visits are for flu-like illnesses, she said.

"It's unprecedented for this time of year to see the whole country seeing such high level of activity," she said.

Remember, kids, there is a middle ground between blind panic and a trip down the River Denial!

Cases of swine flu were confirmed early today in Israel and New Zealand, the first definitive proof that the dangerous new virus has spread to Asia.

The World Health Organization, which yesterday raised its pandemic threat level from 3 to 4, two levels below a full-scale pandemic, will not meet today to consider another increase, a spokesman said at a news conference.

While the agency said people should think carefully before traveling to or from areas known to be affected by the flu virus, spokesman Gregory Hartl said it considers formal travel restrictions and border closures ineffective because people who would be screened could be infected but not yet showing symptoms.

"Border controls don't work. Screening doesn't work," Hartl said, according to Reuters news service, describing the economically-damaging travel bans as basically pointless in public health terms.

He said "we are still at phase 4" in terms of threat level because officials do not yet "have incontrovertible evidence" that the virus spreads easily from human to human. Yesterday was the first time the international body had elevated its official estimation of the threat of an influenza pandemic up from level 3, using a system that was revised in the wake of the 2003 SARS outbreak.

"A pandemic is not considered inevitable at this time," said Keiji Fukuda, the WHO's assistant director general for health security and environment. "The situation is fluid, and the situation continues to evolve."

UPDATE: NYC health authorities say at least eight cases of flu in Queens are probably swine flu (they eliminated types A and B) and two cases were confirmed today in Kansas City.

This is very, very serious, and I'm glad Mexican authorities are treating it as such. One of the key factors in a pandemic flu (a global outbreak) is a mutated strain for which no one has immunity, and of course no one has developed a vaccine yet:

April 25 (Bloomberg) -- The World Health Organization is set to declare the deadly swine flu virus outbreak in Mexico and the U.S. a global concern, potentially prompting travel restrictions, said a person familiar with the matter.

An emergency committee of the WHO in Geneva will declare the outbreak “a public health event of international concern” in a 4 p.m. teleconference today, said the person, who spoke on condition of anonymity because the meeting is confidential. In response, WHO Director-General Margaret Chan may raise the level of pandemic alert, which could lead to travel restrictions aimed at curbing the disease’s spread.

“These levels of pandemic alert are all signals for action,” said Malik Peiris, a professor of microbiology at the University of Hong Kong, who has studied influenza viruses for more than a decade. “Raising the level of alertness to influenza, especially in returning travelers, would be a relevant thing to do.”

Human-to-human spread of the previously unseen H1N1 swine influenza in Mexico and the U.S. is heightening concern that the virus may spark a pandemic. At least 68 people have died and more than 1,000 have fallen ill with flu-like symptoms in the Mexico City region in the past month, Jose Cordova, Mexico’s Health Minister, told reporters yesterday. The government has shut schools and distributed face masks.

Sari Setiogi, a WHO spokeswoman in Geneva, declined to comment on the agency’s response, saying it will depend on the outcome of today’s meeting.