Unless hundreds or thoudsands come down with this in 24 to 48 hours, then its safe to assume this is one of those yearly isolated incidents and not a terrorist attack that got one person.
From another thread:
In the United States, about one case of anthrax has been confirmed each year over the last 10 years, according to a report by Dr. Arthur M. Friedlander, chief of the Bacteriology Division in the U.S. Army Medical Corps.
I don't think you need a hundred cases to confirm terrorism
Also the incubation period covers a range of 12 hours-six weeks. I think 4-6 days was the norm.