For the first time in 90 years, U.S. health officials have diagnosed an airborne person-to-person transmission of the pneumonic plague, but this case began with a pit bull. A total of four people in Colorado were infected, but all recovered once they received the right antibiotics.
In late June, the two-year-old pit bull of a Colorado man fell sick and was taken to a vet. Four days after the trip to the veterinary clinic, the owner developed a cough and fever. He was misdiagnosed by an automated machine at a nearby hospital and developed a lung infection after he was given the wrong antibiotics. A physician noticed the strange reaction to the antibiotics and sent a blood sample to the Colorado Department of Public Health, which identified the bacteria Yersinia pestis.
Once Colorado health officials learned of the situation and began investigating, they discovered that the man’s pit bull had been sick. They tested the dog’s tissue samples at the vet’s office and the samples came back positive for the plague.
"We know that he got it from the dog," said Tri-County's Janine Runfola. "He was coughing up blood. That is likely when some of the cases got infected, including the index patient."
Runfola also said that the man lived in a rural area and the pit bull likely picked up the plague from prairie dogs. According to Dr. John Douglas Jr. of the Tri-County Health Department, the plague is endemic in rodent populations in the western states.
Two employees from the vet clinic and one of the man’s friends, who had handled the pit bull and also had “extended close contact” with the man, all fell sick as well, but only the friend became sick enough to warrant a hospital stay. Health officials believe that she contracted airborne pneumonic plague from the man and not the dog.
Pneumonic plague has not been eradicated in the United States, but outbreaks are typically very small. The U.S. averages eight cases of the plague a year, according to NPR.
With four simultaneous cases, "this event represents the largest outbreak, and the first instance of possible human-to-human transmission, since an outbreak in Los Angeles in 1924," wrote Runfola and colleagues in the Morbidity and Mortality Weekly Report.
While all four infected people survived, the pit bull was euthanized after its illness only worsened at the veterinary clinic.
Douglas recommended that people in the western states take extra caution if they lived near rodent populations or let their dogs spend time outside in rural areas.
“Pets should get flea treatments and be kept away from wild animals,” said Douglas. “Don't let your dog run around where the prairie dogs are. Wear insect repellant and socks.”
Image source: microbewiki.kenyon.edu