See reply 26 by Don Joe.
Don, if you are not going to use mutated anthrax, your field try will have to follow quickly on your trials before the boffins at Fort Detrick and Atlanta can come up with an effective defence and the government can put it in place.
OTOH if you already have a tested mutated anthrax and just need to test distribution modalities, hold your mutated strain in reserve and don't let the Fort Detrick boffins get an advanced look at it.
Testing a disease is not as tough as testing distribution, especially if you have no compunctions against risking lives.
Read up on anthrax antitoxins on this thread: Doctor of cured anthrax patient: 'It was horrendous'.