infectious diseases
Plague and Other Yersinia Infections
Transmission
Plague occurs primarily in wild rodents (eg, rats, mice, squirrels, prairie dogs) and is transmitted from rodent to human by the bite of an infected rat flea vector. Plague may also be spread through contact with fluid or tissue from an infected animal. Human-to-human transmission occurs by inhaling droplets from patients with pulmonary infection (primary pneumonic plague), which is highly contagious. In endemic areas in the US, several cases may have been caused by household pets, especially cats (infected by eating infected rodents). Transmission from cats can be by bite of an infected flea or, if the cat has pneumonic plague, by inhalation of infected respiratory droplets. Pneumonic plague can also be transmitted via exposure in a laboratory or intentional aerosol spread as an act of Biological Agents as Weapons . 