This week, health officials revealed that the first human case of the plague in the state in over eight years occurred in a resident of rural Oregon's Deschutes County.
Humans typically contract plague through flea bites carrying Yersinia pestis or from pets that hunt plague-infected rodents or are bitten by infected fleas.
Pets may transmit the infection to humans through bodily fluids or respiratory droplets, or by bringing fleas into the home, which then bite humans.
Cats are especially prone to plague due to difficulty in clearing the infection and their tendency to chase and catch rodents more than other pets.
Plague is less common in dogs, but in 2014, Colorado saw four human plague cases linked to close contact with an infected pit bull, including its owner and veterinary staff.
Dr. Richard Fawcett, Deschutes County health officer, noted the cat in the recent case was severely ill with a draining abscess, signaling a significant infection.
Fawcett explained the owner's infection, initially bubonic plague in a lymph node, advanced to the bloodstream by hospitalization but responded excellently to antibiotics.
Fawcett mentioned doctors observed the patient developed a cough in the hospital, potentially indicating early pneumonic plague, which spreads between humans.
Fawcett mentioned that, as a precaution, doctors administered antibiotics to close contacts of the patient to prevent the development of any potential infections into symptoms.
Fawcett stated that knowing a patient has the bacteria in their blood prompts a cautious approach, adding he'd be quite surprised to see any additional cases.
Before this week, Oregon's most recent human plague case occurred in 2015, when a teenage girl likely contracted it from a flea bite on a hunting trip, said the state health department.