Plague Fact Sheet

Plague is a severe disease caused by a bacterium called Yersinia pestis

Yersinia pestis is found in rodents (such as rats and prairie dogs) and is passed to humans or other animals by fleas. Plague is rare in the United States and is limited to the western and southwestern parts of the country.

People visiting or working in areas with infected rodents are at risk of catching plague

People with jobs such as hunting and trapping have a greater chance of catching plague. Living in the western and southwestern part of the U.S. and having a house dog or cat can also put people at risk. House pets can bring in fleas, and sick cats can transmit the bacteria by biting or scratching.

Symptoms to look for include:

Fever and chills
Tiredness
Muscles aches
Nausea
Sore throat
Headache
Painful, swollen lymph glands

The symptoms usually start 1 to 7 days after exposure to the bacteria. The first symptom is usually a swollen, red, and tender lymph node (“gland”) in the body near where the infected flea bit the person. The bacteria may spread to the blood and affect many organs including the lungs. People with “plague in the lungs” may spread the disease to other people when they cough. Patients with “plague in the lungs” should be quarantined (isolated from others) until 48 hours of antibiotics have been completed and symptoms are getting better.

Plague can be treated with antibiotics

Certain antibiotics are used to treat the disease and should be started early. If untreated, about half of infected persons will die. There is a vaccine that provides some protection from infection, but it doesn’t last for very long, and is only recommended for certain travelers.

Steps to take to prevent the spread of plague:

Control rodent and flea populations.
Avoid contact with rats, prairie dogs, and other rodents.
Avoid flea bites by using insecticides and repellents.
Rat-proof buildings, store food appropriately, and dispose of garbage.
Wear gloves when hunting or handling wildlife.

Information for Persons Who May Have Been Exposed to Plague

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Maryland Department of Health & Mental Hygiene
— Epidemiology & Disease Control Program
May 2002