The Kansas Department of Health and Environment has confirmed at least two cases of swine flu in the state, while the New York City Department of Public Health reported at least eight out of an estimated 100 students at a Queens prepatory school who displayed flu-like symptoms likely have the infection.
Meanwhile, Imperial County health officials reported that San Diego has yet another case of the swine flu strain that has killed up to 68 people in Mexico.
The escalation in the swine flu situation on Saturday underscored concerns by international, federal and local health agencies over the threat of the new virus, even as government health officials said much remains unknown.
But if one thing is clear about the spread of this virus, it is that containment is no longer an option.
"It's clear that this is widespread," said Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases, at a press conference Saturday afternoon.
"We do not think that we can contain the spread of this virus," Schuchat added. "Having found virus where we have found it, we are very likely to find it in other places. ... We are not at a point where we can keep this virus in just one place."
The cases further demonstrate that health officials do not know where else the virus might turn up. Details of swine flu's spread in Mexico also remain murky. A team sent by the Centers for Disease Control and Prevention is now on the ground there seeking clues on the origin and spread of the disease.
What also remains unclear is why the virus seems to have led to more severe illness in Mexico than in the U.S. -- at least for now.
"What we still don't know is how widespread it is," said Dr. William Schaffner, chairman of preventive medicine at Vanderbilt University Medical Center in Nashville, Tenn. "The question is: How long have things been going on in Mexico, and how attentive have they been in terms of what's going on in their country?"
Meanwhile, emergency departments in affected areas are preparing for what they said could be a rise in cases.
"It is quite conceivable that it could escalate fairly rapidly," said Dr. Richard Bradley, chief of the Division of EMS and Disaster Medicine at the University of Texas Health Sciences Center at Houston. "If we are seeing a flu epidemic in Mexico, we should expect an uptick fairly quickly in Texas, where I am, and in California."
Still, Bradley said that the situation thus far has been relatively fortunate.
"Right now, we are in the increased awareness phase -- we don't yet know how this is going to develop," he said. "Fortunately, right now the cases in California and in Texas seem to be milder than the cases we've seen in Mexico. We hope that this trend continues in the U.S."
Emergency departments in other areas of the country also are stepping up efforts to control the virus should it surface.
Dr. Lewis Goldfrank, professor and chairman of the Department of Emergency Medicine at Bellevue Hospital in New York City said that though no cases have been detected in his emergency department yet, any patient who comes in with a cough and a fever or a rash and a fever is isolated for a nasal swab to detect influenza -- a test that takes about an hour.