Better Take Your Vitamins Before You Protest, Boys and Girls

Now I'm not too much of a tin-foil hat conspiracy theorist, but take this into consideration. On September 24th during an Iraq War protest, which featured the controversial Cindy Sheehan, the environmental air monitors picked up something strange on DC's national mall. Apparently, these monitors that help to detect signs of bio/chemical terrorism picked up evidence of a small amount of the disease agent Francisella tularensis, commonly known as "rabbit fever".

Now only 5% of untreated cases are fatal, but it does make for an uncomfortable time for the 95% majority. The non-contagious disease causes sudden fever, chills, muscle aches and pneumonia-like symptoms but is easily treated with antibiotics. Now this is a rare thing to find on the national mall when the majority of the 200 or so annual cases are in rural environments. Most people get infected with direct contact with a rabbit carcass (hence the name) or with a tick or other insect. My question:

Why was this rare, rural bateria air-borne and circling our nation's capital during a war protest with enough concentration to be detected by a BioWatch system?

All I'm saying is make sure you take your vitamins before you protest, boys and girls. Or at the very least, take a face mask.