In a typical year, 36,000 Americans die from common influenza strains. U.S. life insurance companies incorporate those projected deaths into their grim calculations to remain profitable.

But if the bird flu starts spreading person to person and sparks a global pandemic, as some experts fear, deaths would soar. And if it gets as bad as the 1918 killer flu, it would cost insurance companies a staggering $133 billion in U.S. claims alone, according to estimates by the Insurance Information Institute, a trade group.