Lead: A case of the flu is considered by most people a minor irritant, the subject of humor, the excuse to take off a day or two from work, one of those occasional hardships of life that must be endured. In the winter of 1918, however, the flu was no joke.

Tag: A Moment in Time with Dan Roberts.

Content: Influenza is a virus, a clever survivor, ever vigilant for opportunities to mutate and spread. Many experts believe that the flu virus lives harmlessly in birds. On occasion flu viruses from birds infect pigs, whose immune system then attacks the virus, causing it to mutate. The new virus created in this process is then passed to humans and, depending on the conditions, an outbreak may not be far behind.

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