Biological and chemical weapons not only attack the body, they also attack the mind. The media recognizes this and jumps all over any chemical and biological weapon story. This, naturally, makes a lot of people nervous. An unpleasant side effect of this is outbreaks of hysteria that can appear to be chemical or biological attacks. Since Anthrax was found mailed to several journalists and politicians, there have been many false alarms where large numbers of people reported symptoms indicating some kind of attack. This happened in a Los Angeles subway in September, a New York City high school in October and in many other places where Anthrax was suspected (but was not found.)