Complete Bird Flu Survival Guide

The Spanish flu of 1918 was a terrible pandemic. In a few months, it killed more people than any other illness in recorded world history -- an estimated 20 million to 50 million worldwide, including roughly 550,000 in the United States.

In severe cases, victims' lungs filled with fluid and they essentially drowned in a disease process that took less than a week. It was known for being particularly dangerous to young adults, a group usually less susceptible to flu complications than younger and older people.