What is plague (Yersinia pestis)?

board of animal health

Reportable Disease of the Month

Plague (Yersinia pestis)

What is it?

Plague is serious disease which can infect people and pets. It is caused by the bacteria Yersinia pestis and is most often carried by fleas and rodents. The last plague epidemic to strike the U.S. occurred in Los Angeles in 1925. However, cases continue to be identified in the southwestern United States and in multiple countries around the world. Plague is not endemic in Minnesota and there have not been any reported cases of plague in humans or animals exposed in Minnesota. Nevertheless, it is important to be alert for cases in animals that have recently been in an endemic area. Hundreds of species are susceptible to Yersinia pestis including dogs and cats, which are of great concern because of their frequent interactions with people.

How is it transmitted?

Fleas carry the bacteria and bite either a rodent or another animal, such as dogs and cats, to transmit the disease. Dogs and cats can also become infected by biting, or being bitten by, an infected rodent or rabbit. If an infected rodent dies of the disease, any fleas it carries will seek a new host and can continue to spread the disease. Infected dogs and cats can spread the disease to people through body fluids, bites or scratches or by bringing infected fleas into the house.

Veterinarians are at risk of contracting the disease when examining suspect animals and should use appropriate personal protective equipment (gloves and mask) to reduce the chances of transmission.

What are the clinical signs?

Cats are at a greater risk of becoming ill than dogs, however, their clinical signs are similar. Cats and dogs will exhibit fever, lethargy, enlarged lymph nodes, vomiting, diarrhea, dehydration and respiratory distress. Some animals like cattle, horses, sheep and pigs are unlikely to develop clinical signs if infected. Veterinarians should note the signs of plague mirror the signs of tularemia, which is endemic to Minnesota.

How is it diagnosed?

Veterinarians can collect nasal and oral swabs from infected animals, or fleas if they can be captured. However, in order to confirm the disease, swabs should be collected before giving the animal an antibiotic. Culture of blood and fluid samples can also be used to test for the disease. An approved laboratory will run isolation tests to confirm the bacteria as Yersinia pestis.

What is the treatment?

Antibiotics can effectively treat plague infections. It’s important to bring your animal to your veterinarian as soon as possible if you suspect this disease because early intervention increases the chances of successful treatment.

Is there a risk to people?

People can become infected through flea bites, direct contact with infected pets, and eating meat from an infected animal. It’s important for pet owners to routinely monitor pets for illness and use flea and tick prevention measures to reduce risk. Because symptoms in people can be similar to other illnesses, you should see your doctor immediately if you have concerns.

How can it be prevented?

Plague risk can be reduced by controlling the infection in carriers and flea environments. Measures include rodent control, flea and tick prevention for pets, thoroughly cooking meat, avoiding contact with wild animals, and using personal protective equipment if handling high-risk animals. Reduce the risk of transmission to cats by keeping them indoors. There is no vaccine available for animals.

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