Swine Flu: What You Need to Know

April 26, 2009— -- As U.S. officials warn of the spread in swine flu cases across the country, there are a number of steps Americans can take to protect themselves and their children from this unique virus.

The rapidly spreading swine flu is a new virus that includes combination of swine, bird and human strains. It has taken the lives of 81 people in Mexico, and sickened more than a thousand south of the border.

In the United States, 20 cases have been confirmed thus far -- seven in California, two in Kansas, eight in New York City, one in Ohio and two in Texas.

Simple preventive measures, such as washing hands frequently and avoiding people who are coughing or sneezing, can go a long way toward keeping Americans safe from the virus, which health officials expect is likely to afflict more people.

"There is a role for everyone to play when an outbreak is going on to try and reduce the impact," said Dr. Richard Besser, acting director of the Centers for Disease Control and Prevention (CDC). "At an individual level, it's important people understand how they can prevent respiratory infection. Frequent handwashing [is an] effective way to reduce transmission of diseases."

The World Health Organization declared the unusual virus a "public health emergency of international concern," but fell short of calling it a pandemic.

A flu virus can reach pandemic status if three conditions are met, according to the World Health Organization.

First, it must be an infection that has newly emerged. Secondly, it has to be able to cause serious illness in humans. And thirdly, it must be able to spread easily from person to person. Infections in this category can often spread beyond their continents of origin -- and potentially around the world.

When a flu virus mutates in such a way that it forms a novel version, it means people typically have little to no protection, because their immune systems have no experience fighting that form of the virus. Flu viruses can spread quickly and potentially cause more severe illness when the population lacks immunity.

Scientists around the globe are working hard to determine the threat level of the current swine virus. Right now, the virus is said to have "pandemic potential" because it is a new virus that can spread from person-to-person.

But if it turns out the virus does not spread easily among people, the threat level will go down. Similarly, if it turns out the virus can spread easily among people, the threat becomes more serious and the virus is more likely to trigger a pandemic.

"The distinction about a pandemic is that you need a distinct virus that human population hasn't seen before. Once it starts to spread, it moves rapidly from country to country and from continent to continent and we don't have that yet," said Dr. William Schaffner, chairman of Preventive Medicine at Vanderbilt University Medical Center in Nashville, Tenn.

He added that it is still too early to use the "P" word just yet.

"I'm still observing this as a variant of seasonal influenza. I don't know if we've seen that kind of [global] spread yet so I'm a little bit cautious. However it's in everyone's mind," he said.

But all pandemics are not equally deadly. Some kill millions more people than normal flu outbreaks, while others are roughly on par with seasonal flu in terms of deaths.

It is not possible to predict a pandemic in advance, so health officials keep a close watch on viruses that have "pandemic potential" -- new viruses that have shown at least some ability to transmit to humans.

The current H5N1 bird flu circulating in Asia is an example of a virus that has pandemic potential, but has not yet caused a pandemic.

Pandemics can vary quite a bit in severity. The 1918 pandemic killed many more Americans than an ordinary flu, while the 1968 version killed about 34,000 people -- about the same number killed each year by seasonal flu, according to CDC statistics.