Mmm. Well I suppose you can never rule out a commited lunatic having access to the actual bacteria and choosing to spread it, although Ivins (assuming we accept he was the guilty party) deliberately targeted people- this illness wouldn't do that, it would spread very quickly, killing a good proportion of them. i'm not saying that there aren't people who might want to do that, but the intersection of people who want to do that and people with access to it is hopefully rather low- after all, the anthrax attack was an exception.