Tularemia,Francisella tularensis, is known as Pahvant Valley plague, but is better known as Rabbit Fever and is not to be confused with what is generally known as The Plague (the Black Death, killer of 1/3 of Europe), Yersinia pestis, as seems to be implied by the doctor's reference to it in this episode. Its symtoms include fever, lethargy, anorexia, septicimic signs and inflammed lymph nodes that sometimes suppurate - which does look like the bubonic plague. The respiratory signs the doctor mentioned, however, are not associated with Tularemia or Bubonic Plague. Plague used to be said to have the bubonic strain and a respiratory strain (which was a more certain death than the bubonic) but that has since been disproved by analysis of Yersinia pestis. It is now thought to be likely that other illnesses contributed to the dramatic loss of life. Interestingly, in September of 2005 Tularemia was detected on the Mall in Washington, D.C after an anti-war demonstration. No infections were reported, however.