Some very rough estimates

...in 1997, [Avian flu] claimed its first human fatality, a 3-year-old Hong Kong boy. Since then, the toll has grown slowly but steadily. In the past 14 months, the virus has sickened 69 people and killed 46, mostly in Vietnam and Thailand, according to the World Health Organization.

But it's not a death count that has scientists spooked. About 70 percent of people infected with avian flu die from it. The mortality rate for the Spanish flu, by comparison, was less than 3 percent. The fear is that if natural genetic mutations make the virus more capable of being transmitted from person to person, it could ravage the globe.

Here is the article.