Plague

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Antibodies

Flea

Flea bite - close-up

Plague is a severe, and potentially deadly, infection. It is caused by the organism Yersinia pestis. Wild rodents, like rats, spread the disease to humans.

Bubonic plague; Pneumonic plague; Septicemic plague

Plague is spread among rodents by a flea bite. Humans may get the plague when they touch or eat the infected animal, or when they come in contact with it's feces. 

Certain forms of the plague can be spread from human to human. When a plague victim with pneumonia coughs, microscopic droplets carrying the infection move through the air. Anyone who breathes in these particles can catch the disease. An epidemic may be started this way. (In the Middle Ages, massive plague epidemics killed millions of people.)

Plague is rare in the United States, but has been known to occur in parts of California, Utah, Arizona, Nevada, and New Mexico.

There three most common forms of plague are:

• Bubonic -- an infection of the lymph nodes.
• Pneumonic -- an infection of the lungs.
• Septicemic -- an infection of the blood.

The incubation period is typically 2 to 10 days, but may be as short as a few hours for pneumonic plague.

Risk factors for plague include a recent flea bite and exposure to rodents, especially rabbits, squirrels, or prairie dogs, or scratches or bites from infected domestic cats.

Review Date: 06/17/2005
Reviewed By: Rocio Hurtado, M.D., Division of Infectious Disease, Massachusetts General Hospital, Boston, MA. Review provided by VeriMed Healthcare Network.