The US government is preparing to test an experimental bird flu vaccine and is increasing disease surveillance in hopes of reducing the toll from any eventual American outbreak.
Antiviral drugs are being stockpiled, and two million doses of vaccine are being stored in bulk form for possible emergency use and to test whether they maintain their potency.
United Nations officials warned yesterday that the Asian bird flu outbreak poses the "gravest possible danger" of becoming a global pandemic.
Dr. Julie Gerberding, director of the US Centers for Disease Control and Prevention, said this week that "it is a worrisome situation," though she also said the United States "is not immediately on the brink of an avian flu epidemic".
The flu has affected poultry in eight Asian countries, with 45 human deaths among people who caught the illness - a strain of flu known as H5N1.
So far, humans appear to have caught this flu from chickens and other poultry, and the virus is not known to have spread from person to person.
What health authorities most fear is that the virus will mutate into a form that can pass easily from one human to another, making a global threat more likely.
The deadly flu of 1918, which killed from 20 million to 50 million people worldwide, didn't appear suddenly but mutated gradually into the deadlier form, Dr Gerberding explained.
AP