According to the World Health Organization (who), bird flu has spread from human to human for the first time. Although the virus died out before a pandemic began—killing six of the seven people who contracted it—this is a foreboding demonstration of why bird flu is so dangerous.

Avian flu, also known as bird flu, is an influenza virus typically hosted only by birds, although other animals such as pigs have carried similar infections as well. In the 1918 Spanish flu pandemic, an avian flu killed more than 40 million human beings. This latest strain is called h5n1.

According to who, three things are necessary for a human pandemic to occur: 1) A new influenza type emerges. h5n1 easily meets this criterion. 2) It infects humans, causing serious illness. Since it kills most humans who contract it, h5n1 easily meets this criterion as well. 3) It spreads easily and sustainably among humans. This is where h5n1 has fallen short—until now.

Lee Jong-Wook, leader of who, left no wiggle room on this issue: “It is only a matter of time before an avian-flu virus—most likely h5n1—acquires the ability to be transmitted from human to human, sparking the outbreak of human pandemic influenza. We don’t know when this will happen. But we do know that it will happen” (Nov. 7, 2005).

Now, we have seen a real life demonstration of that third step. A woman in Indonesia contracted the disease, then spread it to her 10-year-old son and five other blood relatives. All but one who contracted the disease died. Because this particular strain has died out, there will not be a pandemic this time. But there is absolutely no reason to believe the virus cannot mutate again, potentially spreading to millions.

United Nations bird flu chief David Nabarro said this is a “vivid reminder of the need to keep a very close watch on what the virus is doing” (Washington Times,June 24). A pandemic of bird flu would be an unprecedented disaster. Economically, the World Bank warned that a bird flu pandemic could cause global gross domestic product to drop by 2 percent—or about $800 billion a year. It is difficult to estimate a reasonable death count, but who forecasts have consistently remained at 2 million to 7.4 million deaths worldwide. While calling that estimate “reasoned,” a who spokesman also warned that “you could pick almost any number.” The UN coordinator for avian and human influenza picked from 5 to 150 million people dead.

For more information on the danger posed by bird flu, read our article from the January 2006 issue, “Is Bird Flu Really A Threat?”