But what if a different, deadlier type of flu started to quickly spread? One bug now has some researchers worried, and they are using computer technology to figure out how best to fight a potential outbreak.

In 1997, a type of flu found in poultry infected 18 people in Hong Kong and 6 of them died. As this bird flu spread to other fowl and moved into other areas of Southeast Asia, more human cases appeared. To date, 112 people have caught bird flu and more than half of them have died. This number may seem small compared to the thousands who die annually from flu-related complications, but for some health officials the bird flu deaths may be an early warning for a deadly worldwide outbreak.

Fortunately, the bird flu doesn’t currently spread easily from person to person, but a change in the virus could soon make this possible. If this happens, an outbreak could quickly spread across the globe to become a pandemic. Because most people haven’t been exposed to bird flu and have no natural protection against it, millions could get sick and even die. The two most recent pandemics caused by a combination of bird and human flu viruses, in 1957 and 1968, killed more than 100,000 Americans. The 1918 flu pandemic caused more than half a million deaths in the U.S. and up to 50 million worldwide.

Researchers can’t predict when or even if the bird flu in Southeast Asia could turn into a pandemic. But to be better prepared in case an outbreak begins, scientists are working to understand the virus, its impact and what can be done to prevent its spread.

“The pressing questions are if and how we can contain an outbreak of [bird] flu at the source before it becomes a pandemic,” said Dr. Ira Longini, Jr. of Emory University, a member of a research group supported by NIH’s National Institute of General Medical Sciences (NIGMS) that’s using computers to investigate what we can do to stop an outbreak at the source.

Longini and his colleagues created computer models, virtual laboratories where they could study different situations based on actual data. These models, built on census statistics collected by the Thai government and information about the infectiousness of previous flu viruses, let the researchers model mock bird flu outbreaks in Southeast Asian communities.

With each scenario the researchers developed, they watched what happened as the virus spread across the virtual map. Did vaccinating people, even if the vaccine didn’t work very well against the new virus, slow the flu’s spread? Did antiviral drugs, which can lessen flu symptoms and prevent new infections, help contain the infection? Was quarantining people effective?

The researchers found that a combination of measures, like giving antiviral medications plus quarantining everyone near an infected person, could stop the virus in its tracks if started early enough. Additional strategies, including vaccination, were needed when the virus was more contagious.

The scientists will adjust the computer models in response to new information about the bird flu and human cases. “As these modeling approaches develop, they will offer policymakers and researchers powerful tools to use in strategic planning,” said NIGMS director Dr. Jeremy M. Berg.

These computer models are just one way that NIH-supported scientists are working toward understanding and preparing for a bird flu pandemic. Researchers funded by NIH’s National Institute of Allergy and Infectious Diseases (NIAID) have tested and shown that one of the antiviral drugs currently used to treat the symptoms of seasonal flu also could work for bird flu. Other NIAID researchers are testing a bird flu vaccine and expect results by the end of the year.

Each year in the United States, more than 100,000 people are hospitalized and about 36,000 people die from the flu and its complications, the Centers for Disease Control and Prevention estimates. Understanding how flu spreads and how the tools we have affect its spread are crucial to fighting future outbreaks.