Plague

Plague is a bacterial illness caused by Yersinia pestis. This bacteria is naturally present in some wild rodents and other animals in the western United States. Humans can become infected through rodent flea bites, handling tissues or body fluids from infected animals, or respiratory droplet spread from animals or people with pneumonic plague.

Types of Plague

Plague can be spread in several ways. The illness that results is based on how the bacteria enter the body.

Bubonic plague — When Y. pestis bacteria enter the body through the bite of an infected flea or through a cut or break in the skin, the bacteria multiply near where they entered the body, and the resulting disease is called bubonic plague. “Buboes” are swollen painful lymph nodes. Bubonic plague is the most common form of the disease. If untreated, it may progress to septicemic plague.
Septicemic plague — When Y. pestis bacteria accumulate in the bloodstream, septic shock occurs and the resulting disease is called septicemic plague.
Pneumonic plague — When Y. pestis bacteria are inhaled, they infect the lungs and the resulting disease is called pneumonic plague. Pneumonic plague can also occur when bacteria spreads to the lungs of a patient with untreated bubonic or septicemic plague. Pneumonic plague is of particular concern because it can be spread from person to person.

Symptoms of Plague

Bubonic plague can cause fever, headache, nausea and one or more swollen, painful lymph nodes.
Septicemic plague can cause fever, extreme weakness, abdominal pain, and multi-organ system failure.
Pneumonic plague can cause fever, headache, weakness and a bloody or watery cough due to infection of the lungs (pneumonia). The pneumonia rapidly becomes worse and — without early treatment — it can be fatal.

If you have symptoms after exposure to wild rodents, fleas, or sick animals, consult a healthcare provider as soon as possible and alert them to your exposure. If you believe you have been intentionally exposed to pneumonic plague, you should contact law enforcement officials immediately.

There is no vaccine against pneumonic plague. Antibiotics are used to prevent illness in people who have been exposed to plague. Early treatment with appropriate antibiotics is essential because untreated plague — especially the pneumonic form — is almost always fatal. You should use antibiotics to prevent or treat plague only under the direction of your healthcare provider or local health department.

How to Protect Yourself and Others

Prevent rodent infestation by removing sources of food, trimming vegetation around your home, storing firewood at least 12 inches off the ground and away from your home, and sealing up all gaps and holes into your home or outbuildings.
Avoid contact sick or dead wildlife when possible. If you need to dispose of a dead animal, wear a well-fitting face mask and disposable gloves. Use an inside-out plastic bag to pick up the carcass. Double-bag the carcass and throw it away in a sealing trash can. Wash hands with soap and water immediately.
Use repellent if you think you could be exposed to fleas during activities such as camping, hiking, or working outdoors. Products containing DEET can be applied to the skin as well as clothing and products containing permethrin can be applied to clothing (always follow instructions on the label). Take care when applying repellent on children. Use EPA's Find the Repellent that is Right for You search tool.
Prevent plague in your pets (see Pets and Plague section) by applying flea control products and preventing pets from roaming freely.
Don't allow dogs or cats that roam free to sleep on your bed.

Pets and Plague

Cats are highly susceptible to plague and are a common source of infection in humans, especially owners and veterinarians. Dogs infected with plague are less likely to get sick. Cats (and sometimes dogs or other animals) with pneumonic plague can pose a significant risk to owners, veterinarians, and others who handle or come into close contact with these animals due to possible aerosolization of bacteria. Transmission to humans can also occur directly by bites, scratches, and contact with infectious fluids or indirectly from exposure to infected fleas on pets.
If you live in areas where plague occurs, speak with your veterinarian about regular, effective flea control medicine for pet dogs and cats and don't allow these animals to roam freely. Animals that roam freely are more likely to come in contact with plague infected animals or fleas and could bring them into homes. If your pet becomes sick, seek care from a veterinarian as soon as possible.
Do not allow pet dogs and cats to kill or scavenge dead animals.

Plague in Washington State

Serologic sampling of 8,921 wild carnivores collected between 1975 and 2014 in Washington showed 2.5% seropositivity. Only one animal has tested positive since 2003. The majority of animals tested in recent years were from the Yakama Nation Wildlife Department. Other surveillance partners include the Department of Fish and Wildlife's licensed nuisance trappers, the Makah Tribe Forestry-Wildlife Division, and Joint Base Lewis-McChord Yakima Training Center. Human infections are rare; the last reported case in a Washington resident was an animal trapper in Yakima exposed while skinning a bobcat in 1984.