Experts Debate Pandemic Potential of Swine Flu

April 24, 2009— -- A top federal health official said the government's concern over the swine flu outbreaks in the United States and Mexico has grown since Thursday -- and a handful of influenza experts worry the deadly, never-before-seen hybrid strain may spur a pandemic.

Dr. Richard Besser, acting director of the U.S. Centers for Disease Control and Prevention, said that health officials confirmed yet another U.S. case of swine flu in California today, bringing the total number of Americans infected with the disease to eight.

Though it is still too early to say for certain whether a swine flu pandemic is possible or likely, the cases, all of which have occurred in California and Texas, have aroused concerns among the public, Besser acknowledged.

"We are worried as well," he said. "Our concern has grown since yesterday in light of what we've come to know since then."

Thus far, the first seven Americans found to have contracted the new variant have recovered, which Thursday led health officials to urge calm while the investigation into the virus continued.

Dr. Anne Schuchat, director of the CDC's National Center for Immunization and Respiratory Diseases, had said during a Thursday afternoon press conference that the strain did not "[look] like a very severe influenza. ... We don't think this is time for major concern around the country."

The sentiments were echoed by Canada's Dr. Michael Gardam, director of infectious disease prevention and control at Ontario's public health agency, in a Thursday night interview with the Canadian Broadcasting Corporation. Moreover, the World Health Organization has not yet made a change to the pandemic threat level -- the established worldwide barometer for pandemic threat.

Still, Mexican officials reported that what is believed to be the same mutant strain of swine flu already has killed at least 16 people in Mexico, and possibly as many as 61.

Swine Flu Outbreaks a 'Serious Situation'

John Barry, author of "The Great Influenza," said he believes there is a chance that the infections signal the beginning of the next pandemic -- a global disease outbreak that occurs when a new virus emerges for which there is little or no immunity in the human population, begins to cause serious illness and then spreads easily person-to-person worldwide.

"Obviously, this is an extremely serious situation," he said, adding that the real determinant as to how dangerous this virus will become lies in how easily it is spread from person to person.

"If the virus is halfway efficient at that transmission, we have the next pandemic," he said. "No way it can be contained in a place like Mexico City, and it's already in California, and probably some places -- if not every place -- in between."

Barry is not the only one to harbor such concerns.

"If 16 to 60 out of about 800 cases in Mexico have died, then this is indeed a serious public health threat deserving of the full attention of the U.S. public health infrastructure," said Robert Garry, a microbiologist at Tulane University.

And Dr. Martin Blaser, chairman of the Department of Medicine at New York University Langone Medical Center, agreed the situation is serious.

"This is worrisome, because it is a swine, avian, human recombinant; it involves people who do not have any obvious exposure to swine," he said.

He further noted that the patterns of spread so far point toward the possibility that the virus may have been spread through human-to-human contact.

"It could just represent the results of improved surveillance by the CDC -- they have stepped up flu surveillance -- or it could be a low level transmission of a newly emerging strain," he said. "Or [it] could possibly be the start of a new epidemic."

Not Time for Panic, Some Argue

Despite the prevailing concern over the swine flu cases, other infectious disease experts believe that it is not quite time to consider this virus a major public health threat.

First of all, it would not be the first time the country has encountered a pandemic. In the 20th century alone there were three pandemics of influenza.

The worst was the 1918 influenza pandemic, which caused at least 675,000 U.S. deaths and up to 50 million deaths worldwide. The 1957 influenza pandemic caused at least 70,000 U.S. deaths and 1 million to 2 million deaths worldwide, while the 1968 influenza pandemic caused about 34,000 U.S. deaths and 700,000 deaths worldwide -- only about as many deaths as a normal flu season.

Some Protections Already in Place to Curb Swine Flu

Flu experts also point out that several conditions must all be satisfied at once for a full-blown pandemic to occur.

"[There] is a very low probability [that this is will be a] high-consequence scenario," said Dr. Peter Katona, associate professor of clinical medicine at The David Geffen School of Medicine at UCLA. "The potential is there to do great harm, but many factors -- season of the year, level of hygiene, robustness of the virus -- have to come together for the 'perfect storm' to happen."

Moreover, some experts pointed out that the increased diagnosis of these cases of swine influenza in humans was an accidental result of increased CDC flu surveillance. Therefore, there was no cause for concern about the new influenza strain before the CDC accidentally identified it.

"It is of note that the two cases in California were 'accidental' findings, as both infected children were treated in facilities that carried out clinical studies," said Nicole Baumgarth, chair of the graduate group in Immunology at the University of California at Davis. "Identification of the virus was done therefore by 'looking harder' rather than because of clear suspicion of influenza. ... Increased surveillance will result in increased diagnosis."

Another advantage that health officials enjoy is the fact that while the virus appears to be resistant to at least two weapons in the antiviral arsenal -- amantadine and rimantadine -- it is still susceptible to the popular flu drugs oseltamivir (Tamiflu) and zanamivir (Relenza). Besser said that scientists are also already starting work on a preliminary vaccine for the illness.

And he said the country is prepared to deal with the threat of a pandemic-level virus should the situation escalate.

"The level of planning that has taken place in this country is unprecedented," he said, adding that preparations in recent years would allow U.S. health officials to respond to a pandemic threat far more effectively than in the past.

Disease Agencies Mobilize Against Swine Flu

Mexico, meanwhile, is taking no chances. A government order Friday closed Mexico City private and public schools, from pre-school through university level. The Associated Press also reported that Friday afternoon, the country's government closed museums, libraries and state-run theaters in Mexico City in an effort to curb the outbreak.

Besser said that U.S. health officials are currently working with their Mexican counterparts to learn more about the strain, but he said there was much more to be done.

"While we are now working with health officials in Mexico, we are very early on in those efforts," he said. "We need more complete lab analyses and better understanding with regard to the number of people experiencing influenza-like illness in Mexico."

He added that the CDC has already sent a team to California to learn more and will likely send a team to Texas as well. Thus far, the CDC has issued no travel restrictions to any of the locales.

Protecting Yourself From Infection

If there is one point on which all infectious disease experts agree, it is that this flu strain should be monitored closely. More importantly, the public should also take on increased hygienic measures to avoid contracting the virus.

The CDC currently recommends that you cover your nose and mouth with a tissue when you cough or sneeze, wash your hands often with soap and water, avoid touching your eyes, nose or mouth, and try to avoid close contact with sick people.

The CDC also suggests that if one does contract an illness, they should stay home from work or school and limit contact with others to avoid spreading the infection.

If you develop an illness with fever and respiratory symptoms and you live in or near a region in which the virus has been identified, the CDC recommends that you immediately seek attention from your health care provider to determine whether further influenza testing is needed.

"Good nutrition that promotes host defense and control of any underlying diseases that may make someone high risk ... is also important," said Dr. Len Horovitz, pulmonary specialist at the Lenox Hill Hospital in New York City.

Those who wish to learn more about the government's actions in response to the swine flu cases can access the CDC's swine flu page online at http://cdc.gov/flu/swine. Alternatively, the CDC has also set up a toll-free information hotline: 1-800-CDC-INFO.

Joanna Schaffhausen contributed to this report./