CDC wants doctors on alert for avian flu

As part of the Centers for Disease Control and Prevention's plan to clip the wings of the avian influenza virus now emerging in Asia, the agency wants doctors here to take a travel history for any patient presenting with flu-like illness and test respiratory specimens of those who have been to countries with reports of the disease.

Only one state reported widespread activity for ordinary influenza at the end of January. Avian influenza, however, has killed at least 12 people in Vietnam and Thailand, according to the World Health Organization. No U.S. cases had been detected at press time, but the CDC considers the situation serious enough to warrant action.

"We want to be very vigilant," said CDC Director Julie Gerberding, MD, MPH. "Eleven out of the last 12 emerging infectious diseases that we're aware of in the world that have had human health consequences have probably arisen from animal sources."

The agency is reviewing its domestic infection control guidance and stockpiling anti-influenza drugs -- a process started when the U.S. flu season peaked in early December. It is also working with domestic laboratories to develop tests to detect avian influenza strains and has sent six scientists to Vietnam in an attempt to keep the virus at bay.

Although public health officials say emergence here is unlikely, there are characteristics of this outbreak that make it scarier than the one that occurred in Hong Kong in 1997. This latest strain is different enough that the CDC, in collaboration with the WHO, has to start fresh to develop a seed virus for vaccine production and research. This seed virus, essentially the avian flu with its deadly sting removed, is especially vital because influenza vaccines are grown in chicken eggs but the virus at full strength is lethal to chickens, thus making it difficult to culture.

This strain is also resistant to older influenza drugs, although it has been responding to oseltamivir. Public health officials suggested that in some high-risk situations the drug might be used as a prophylactic.