Plague is a severe and potentially deadly bacterial infection.

Plague is caused by the organism Yersinia pestis. Rodents, such as rats, spread the disease to humans.

People can get the plague when they are bitten by a flea that carries the plague bacteria from an infected rodent. In rare cases, you may get the disease when handling an infected animal.

Certain forms of the plague can be spread from human to human. When someone with the plague 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 plague is an infection of the lymph nodes.
• Pneumonic plague is an infection of the lungs.
• Septicemic plague is an infection of the blood.

The time between being infected and developing symptoms 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.

Bubonic plague symptoms appear suddenly, usually after 2-5 days of exposure to the bacteria. Symptoms include:

• High fever
• Smooth, painful lymph gland swelling called a buboe
  • Commony found in the groin, but may occur in the armpits or neck
  • Pain may occur in the area before the swelling
• Chills
• General ill feeling (malaise)
• Muscle pain
• Severe headache
• Seizures

Pneumonic plague symptoms appear suddenly, typically 2-3 days after exposure. They include:

• Severe cough
• Frothy, bloody sputum
• Difficulty breathing

Septicemic plague may cause death even before the symptoms occur. Symptoms can include:

• Abdominal pain
• Blood clotting problems
• Diarrhea
• Fever
• Low blood pressure
• Nausea
• Organ failure
• Vomiting

Tests that may be done include:

• Blood culture
• Culture of sputum
• Lymph node culture

Persons with the plague need immediate treatment. If treatment is not received within 24 hours of when the first symptoms occured, death may be unavoidable.

Antibiotics are used to treat plague. Oxygen, intravenous fluids, and respiratory support are usually also prescribed.

Patients with pneumonic plague are strictly isolated from other patients. People who have had contact with anyone infected by pneumonic plague are observed closely and are given antibiotics as a preventive measure.

Without treatment, about 50% of those with bubonic plague die. Almost all persons with pneumonic plague die if not treated. Treatment reduces the death rate to 5%.

Call your health care provider if symptoms develop after exposure to fleas or rodents, especially if you live in or have visited an area where plague occurs.

Rat control and surveillance of the disease in the wild rodent population are the main measures used to control the risk of epidemics. A vaccination is available for high-risk workers, but its effectiveness is not clearly established.

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Josko D. Yersinia pestis: still a plague in the 21st century. Clin Lab Sci. 2004 Winter;17(1):25-9.