Yersinia – The Plague in Cats
Yersinia in Cats
Yersinia, also commonly referred to as “the Plague”, has a long history associated with death. In the late 1340s, over 20 million people died in Europe during a two-year epidemic from a disease called Black Death or Black Plague. Later, it was found that the agent responsible for these deaths was a bacteria called Yersinia pestis. Since then each century has seen various outbreaks of the plague. Although many people think that the plague is a distant disease that does not occur in today’s modern world, the Yersinia bacteria and associated plague is still causing illness throughout the world.
Yersinia is a bacteria that is spread primarily by fleas and most commonly infects rodents such as ground squirrels and prairie dogs. Cats can also be infected by the plague bacteria by being bitten by an infected flea, eating infected rodents or inhaling the bacteria. A few people each year are also diagnosed with the plague after being bitten by an infected flea or inhaling the bacteria. Infection in dogs is extremely rare due to their inherent resistance to the Yersinia pestis bacteria. In the United States, cats and people infected with Yersinia have been reported in New Mexico, Arizona, California and Colorado. Infection typically occurs in spring, summer and early autumn.
Most cats affected with the plague are outdoor, male cats that tend to hunt rodents; however, any breed, age or sex can be infected.
Various forms of the plague can develop. The most common form is bubonic plague, which results in swelling of the lymph nodes in the neck; pneumonic plague results primarily in a lung infection; and septicemic plague results in a blood infection.
What to Watch For
- Lack of appetite
- Swollen neck
- Draining abscesses
- Difficulty breathing
Diagnosis of Yersinia in Cats
Within 2 to 6 days after being bitten by an infected flea or 1 to 3 days after ingestion of an infected rodent, signs of the plague can develop in cats. Diagnosing the plague takes specialized tests, particularly culturing of various fluids.
Your veterinarian will perform a complete physical examination and may find swollen lymph nodes, enlarged tonsils, fever, dehydration, abscesses or difficulty breathing. Based on the physical exam findings, diagnostic tests are necessary for a definitive diagnosis of Yersinia.
- A complete blood count will generally reveal an increased white blood cell count. This is consistent with infection but not specific for Yersinia.
- Biochemical profile may show signs of kidney malfunction, electrolyte imbalance, liver malfunction and dehydration. These findings are not specific for Yersinia infection.
- For cats with difficulty breathing, chest radiographs (x-rays) are recommended. Lung consolidation or collapse may be seen.
- Cytologic examination (microscopic) of lymph node aspirates, fluid found draining from open wounds or from airway secretions can help give an accurate diagnosis of Yersinia. The Yersinia bacteria has a characteristic shape.
- Specific blood tests to detect antibodies for Yersinia do not help determine if the cat is infected with the plague. Positive antibody tests indicate that the cat has been exposed to Yersinia at some point, but it does not confirm an active Yersinia infection.
- Definitive diagnosis of the plague requires culture of airway secretions, draining fluid or lymph node aspirates.
Treatment of Yersinia in Cats
The cornerstone of treatment for the plague is antibiotics. Typically, injectable streptomycin, gentamicin or enrofloxacin are used initially until the fever and lack of appetite resolves.
Once the cat is eating, oral antibiotics such as tetracycline or doxycycline can be prescribed. Cats diagnosed with the plague require at least a 3-week course of antibiotics.
Weak, dehydrated and febrile cats required hospitalization with intravenous fluids.
Cats with swelling of the lymph nodes of the neck will need those areas drained and flushed.
Overall, cats with bubonic plague treated with antibiotics have a good chance of survival. The majority of cats with pneumonic or Septicemic plague, as well as untreated bubonic plague, typically do not survive.
Home Care and Prevention
There is no home care for the plague. Extreme caution must be used when handling and treating these cats. Exposure to draining fluid, bites or scratches from the cat or bites from cat fleas can result in transmission of the bacteria to humans.
Keeping your cat indoors will greatly reduce the risk of infection with Yersinia pestis.
Flea control and rodent control is an important part of reducing the chance of exposure to Yersinia.
If your cat is currently being treated for the plague, he is not considered contagious after three days of antibiotics.