Plague is a bacteria that can be transmitted to people through flea bites and direct contact with infected animals. The bacteria can be carried by fleas, which can be found on rodents like prairie dogs, squirrels, rabbits and chipmunks. When fleas bite rodents infected with plague, they become infected and can then spread the disease to other rodents, domestic animals and humans.

In humans, the incubation period is usually 2-7 days.

There are three main forms of plague:

  1. The most common form is the Bubonic plague, characterized by sudden onset of fever, headache, chills, and weakness and one or more swollen, tender and painful lymph nodes (called buboes). This form usually results from the bite of an infected flea. The bacteria multiply in the lymph node closest to where the bacteria entered the human body. Bubonic plague is the most common form of the disease in humans (about 80% of cases) Typical symptoms include swollen lymph nodes, sudden onset of fever or chills, severe headache, extreme exhaustion, and a general feeling of illness. Bubonic plague can be successfully treated when diagnosed promptly. If you have had a possible exposure to infected rodents or fleas and are experiencing these symptoms, consult a physician as soon as possible.
  2. Septicemic plague occurs when the bacteria enter the bloodstream directly and spread throughout the body. These forms are highly fatal unless treated promptly; unfortunately there are often no localizing signs to suggest plague.
  3. Pneumonic plague can result in human-to-human transmission via spread through respiratory droplets. Patients develop fever, headache, weakness, and a rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery mucous.

Untreated bubonic plague has a fatality rate approaching 70%; septicemic and pneumonic plague are fatal without prompt treatment.

Plague can be treated if diagnosed in the early stages of disease. If diagnosis and appropriate treatment are delayed, life-threatening complications may follow. A doctor or hospital emergency room should be consulted as soon as symptoms appear and a history of exposure to potentially infected animals is very important in evaluating the risk from plague.