Bird Flu: Threat or Menace?

Why avian sniffles need not ruffle our feathers... too much


An avian flu pandemic could kill 2 million Americans and 150 million people worldwide.

Claims like that certainly do get your attention. At any rate, they have certainly gotten people's attention in Washington, D.C., where our solons are posturing and bloviating about what the Feds should to do to protect us. Earlier this month, the Senate passed legislation authorizing $3.9 billion to purchase antiviral drugs; President Bush met with and basically hectored all five remaining U.S. vaccine manufacturers; Bush also suggested that he would use the military to enforce quarantines in the event of an outbreak; and Sen. Chuck Schumer (D-N.Y.) is once again trying to suspend a pharmaceutical company's patent, allegedly to protect the public's health.

The advent of this new bird influenza virus, the H5N1 strain, is what's provoking these alarums. But the 1918 Spanish influenza pandemic haunts these discussions. The 1918 outbreak killed between 20 million and 50 million people worldwide including some 500,000 to 675,000 Americans. Since 1918 there have been other flu pandemics. The Asian flu killed 70,000 Americans in 1957-58 and the Hong Kong flu killed 34,000 in 1968. Today, around 36,000 Americans die of influenza and its complications annually. So far, while the H5N1 strain of avian flu has killed tens of millions of birds, it has infected only 116 people, killing 60 of them. Nearly all of the infected people got the disease from intimate exposure to poultry.

The fear among virologists and epidemiologists is that the H5N1 strain will mutate into a form that can be transmitted from person to person. Throughout history the more virulent forms of influenza derived from birds. Flu viruses constantly mutate and change, which is why a new shot of vaccine is needed each year to immunize people against that year's dominant strains. The genes that code for the surface molecules that help flu viruses enter and infect host cells mutate in ways that keep the flu virus ahead of human immune systems. The two chief surface molecules involved with infections are hemagglutinin and neuraminidase, the "H" and the "N" that define different flu strains.

Fifteen different types of hemagglutinin genes and 9 different neuraminidase genes are found in the flu viruses that infect animals. The 1918 pandemic strain was an H1N1 virus; the 1957 pandemic was caused by a H2N2 virus; and the 1968 pandemic virus was a H3N2 version. Since H2N2 viruses no longer circulate among humans, the annual flu vaccine is made by combining the new versions of H1N1 and H3N2 viruses that nature produces each year. Basically, whenever a new hemagglutinin gene managed to make the transition from animals to people, a pandemic occurred. The concern is that while people have developed some immunity to H1, H2, and H3 flu viruses, we are wide open to the H5 strain.

Earlier this month, researchers announced that they had resurrected the flu virus that caused the 1918 pandemic. They hope that their research will shed light on how a bird virus becomes a human virus.

The genome of the 1918 virus is now publicly available, a fact that dismayed technologists Ray Kurzweil and Bill Joy, who argue that we should "treat the genetic sequences of pathological biological viruses with no less care than designs for nuclear weapons." However, the new National Science Advisory Board for Biosecurity reviewed the research and unanimously agreed that alerting other scientists to the findings outweighed the risk that the research might be misused. Besides, Julie Gerberding, head of the Centers for Disease Control in Atlanta, GA noted that the 1918 virus could be less dangerous today since most people have some immunity to H1 flu viruses and because effective anti-virals are now available.

Reacting to the wildly escalating estimates of pandemic flu deaths, the World Health Organization suggested on October 1 that the most likely scenario would result in a death toll of between 2 million and 7.4 million people. That's not nothing, but keep in mind that 2 million people around the world died in the 1957 pandemic.

Are the crash programs, the billions spent on stockpiling medicines, the plans for military quarantines really necessary? The swine flu crisis in 1976 is instructive. In February 1976, a serviceman at Fort Dix in New Jersey fell ill and died of a H1N1 flu virus that seemed related to the 1918 Spanish flu virus. In March, President Gerald Ford announced a crash program to vaccinate every single American against the swine flu. By November some 40 million Americans had been vaccinated before the campaign was called off because several people had died after being vaccinated. The swine flu never appeared. As far as we know, only the soldier at Fort Dix died of it.

The Federal government's recent record at handling emergencies suggests that we should not be very confident that it can protect us against a pandemic flu. Encouragingly, however, the National Science Advisory Board for Biosecurity got it right. At the moment we may still be vulnerable to nature and would-be bioterrorists. But our future security lies with the open and rapid diffusion of scientific knowledge that will enable us to build defenses faster than nature or would-be bioterrorists can devise ways to harm us.