Honestly? This really scares me more than anything out there. You can't see it coming, you just suddenly start coughing and a few hours later you end up dead. Oh and the scarier part? It's very possible. Take for example Anthrax, someone with a grudge against a certain country modifies some Anthrax and releases it inside a public place. Everyone there would most likely die and people would not know what happened for awhile giving the perpetrator time to release more spores.
Scary indeed.