It also remains viable for some time in dry sputum, flea feces, and buried bodies but dies after several hours of exposure to sunlight. For bubonic plague the incubation period is 2 to 10 days. Symptoms include malaise, high fever, and tender lymph nodes. The plague may progress spontaneously with spread to the central nervous system, lungs, and elsewhere. For pneumonic plague the incubation period is 2-3 days.
Death results from respiratory failure, circulatory collapse, and internal bleeding.