Plague currently active in multiple Colorado counties

Plague currently active in multiple Colorado counties

This article was contributed by the State Public Health Veterinarian’s Office.


So far in 2021, Yersinia pestis (the causative agent of plague) has been identified in the counties of Adams, Boulder, Huerfano, El Paso, La Plata, and San Miguel. The bacterium has been confirmed in fleas from prairie dog die-off areas, tree squirrels, domestic cats, and a mountain lion. There has also been a human plague death in La Plata County.

Clinical presentations of the four infected cats:

● Cat One: Fever (104°F), initial presentation with a superficial axillary wound (unknown if truly a wound or a ruptured lymph node) and no lymphadenopathy; subsequently developed signs of sepsis with leukocytosis, thrombocytopenia, and abnormal coagulation panel

● Cat Two: Fever (104°F) and submandibular lymphadenopathy

● Cat Three: High fever (105.9°F) and painful submandibular lymph nodes that were large enough to palpate and aspirate

● Cat Four: Temperature not recorded. Oral abscess (tongue) after being missing for two days, otherwise normal

Cats and occasionally dogs are susceptible to plague and can develop severe symptoms during their illness. People can be infected by close contact with a cat or dog exhibiting respiratory symptoms of plague infection, being exposed to exudates of infected animals, or by being bitten by infected fleas. Veterinarians should ensure appropriate biosafety precautions are followed when handling and treating animals suspected of having plague. Any suspected case of plague is required to be reported immediately.

Clients should be encouraged to keep their animals on flea prevention, prohibit free roaming, and discourage rodent hunting. Any client that is aware of any unexplained rodent die-off should report that information to their local public health agency.

Veterinarians can find a Quick Guide to Management of Suspected Veterinary Cases of Plague at as well as a more extensive document that goes into greater detail. Early antibiotic administration has been very successful at treating pets.

All suspected plague cases should be reported immediately to CDPHE at 303-692-2700 during normal business hours or 303-370-9395 during holidays, weekends, or after hours.