It has been determined that a minor outbreak of plague in Colorado last summer can be traced back to the initial patient’s dog. Generally the plague does not cause much more than a mild illness to dogs. The dog in this case unfortunately did not survive, but there were no human lives lost.
The unidentified man was initially diagnosed with pneumonia in June 2014, but after his condition worsened – severe fever, cough and bloody sputum – doctors realized his symptoms had been caused by the bacteria Yersinia Pestis, which causes pneumonic plague.
After the correct diagnosis was made, the man spent 23 days recovering in the hospital. Meanwhile, Colorado’s Tri-County Health Department discovered that his two-year-old pit bull had recently been put to sleep. The dog also had a severe fever and bloody cough.
“Frankly, one of the biggest surprises of this outbreak is the source,” said John Douglas of Tri-County Health Department told the Associated Press. “Primarily … dogs don’t get sick at all or they get a minor illness” when they have the plague.
Two veterinary workers who had been in close contact with the dog, as well as an associate of the first patient, all contracted the plague and were given medication. Researchers notified 114 people who had all come into contact with the four sick humans, and told them to keep track of any symptoms they might develop.
This form of plague is endemic to the western US. Humans have been known to contract the disease from fleas on prairie dogs, but this is the first documented case of dog-to-human transmission.
The 2014 outbreak was “the largest outbreak and first instance of possible human-to-human transmission since an outbreak in Los Angeles in 1924.” Pneumonic plague is uncommon in the US, and only about eight cases of plague are reported in the US each year. The concern for a massive outbreak is not high, but dog owners should always monitor their dogs for symptoms of serious illnesses.