The 90% mortality rate for anthrax only seems to apply to the inhaled versions. The cutaneous versions don't seem to be nearly as deadly. The fact that anthrax isn't contagious makes it far less dangerous than a disease like smallpox.

The last known case of smallpox anywhere on Earth was in 1976. How many doctors would even recognize it if they saw it? The one potentially good thing is that since the spread of AIDS, medical personnel use "universal precautions" and treat everyone as if they're infected. As a result, the spread might be slowed through aggressive quarantines if it was recognized in time.

If the article I provided is accurate, countries like Iraq and North Korea are believed to have active smallpox programs. To be honest, that worries me a lot more than anthrax. If Iraq has it, odds are so do the terrorists.