In the perennial conflict between germs and humans, the influenza virus has a distinguished roster of battlefield victories. But now, far from America's shores, a new round of hostilities is brewing. For the first time, scientists and public health officials are preparing to fight back.
Across East Asia, an influenza virus known by the scientific designation H5N1 has killed at least 55 people and tens of millions of birds. As potential aggressors go, this one's about as insidious as they get -- fast-moving, deadly and extremely unpredictable. Before it can mount an all-out offensive, this "bird flu" virus must change its genetic makeup so that it can jump easily from human to human. Once it has done so, the resulting germ could spread quickly, inflicting heavy casualties among a global population with no natural immunity against it.
That final shift might never happen -- or it could happen next week. But scientists think that roughly three times each century nature creates an influenza virus capable of global devastation, and a "pandemic" flu sweeps the world. The prospects increase when a virus long out of circulation extends its geographic range, its hold on different animal species and its contact with humans. By those measures, H5N1 is a virus on the march.
So can it be stopped? With a few more years to prepare, American public health experts say they may be able to prevail over an outbreak of pandemic flu. But its timing absolutely defies prediction. If the attack comes this year or next, experts acknowledge they can at best slow its march, and the death toll will be grievous.
Among officials and experts tracking the building force of the H5N1 virus, the anxiety is palpable. Dr. Anthony Fauci, who directs the National Institutes of Health office that oversees preparations for pandemic flu, says the sense of urgency is intense. "I feel it every day, and my staff feels it every day."
Fauci calls pandemic flu "the mother of all emerging infections" and warns that the world is behind in building its defenses.
There is, however, a scramble to get ready. The United Nation's World Health Organization has stepped up its monitoring of H5N1 throughout East Asia. It has brokered cooperation among countries to help stem the spread of the virus -- usually by killing flocks of infected birds. And it has exhorted countries to arm themselves with vaccine and antiviral medication.
In Washington, D.C., and across the United States, officials are racing to prepare for and counter the virus before it becomes efficient at jumping from human to human and is transported to America by a passenger aboard a plane.
They know how quickly the scenario could unfold. When a novel respiratory syndrome called SARS emerged in rural China in 2003, it spread to five countries in 24 hours; within several months, it had reached 30 countries on six continents. The East Asian countries most affected by bird flu so far -- Cambodia, Vietnam and Thailand -- are ill-equipped to track the spread of bird flu in animals and humans. Containing it, say experts, is beyond their powers.
In the last several years, U.S. federal spending on influenza research has increased more than fivefold, to $400 million annually in 2005. Vaccines against two different strains of influenza -- one of them the H5N1 strain -- were rushed through development using new genetic engineering techniques, and have gone into large-scale production at the same time that clinical tests have gotten underway.
The unprecedented compression of the schedule for H5N1 vaccine is risky, Fauci says. But it is "an indication of the urgency" with which officials feel they need to have a vaccine in hand.
President Bush ordered 5.3 million doses of flu-fighting antiviral medications into the strategic stockpile, and in April signed an executive order authorizing the isolation and quarantine of foreigners suspected of arriving at the U.S. border sick with flu. The U.S. Centers for Disease Control and Prevention is expanding the number and capacity of quarantine stations at major U.S. ports. And chastened by flu vaccine shortages last year caused by a production glitch, CDC officials are drawing up plans for distributing limited vaccine and antiviral medication in the event of a pandemic.
"The stakes -- in dollars, resources and human lives -- are enormous," said Rep. Thomas M. Davis III (R-Va.), who on June 30, presided over the fifth hearing this year that Congress has called on the subject.
Officials also face the uncertainty of not being able to predict how virulent a pandemic flu virus would be. Bird flu victims in Asia have been stricken with typical influenza symptoms at first, but their respiratory distress quickly worsens as their immune systems try to fight the virus. Of those confirmed infected with the bird flu, almost half have died.