In an incident that could have implications for therapy and support dogs in healthcare, 116 employees and students in a veterinary teaching hospital were exposed to pneumonic plague by a dog with unrecognized infection, investigators report.1
The scourge of the Middle Ages, Yersinia pestis is now completely treatable by antibiotics, but the prognosis diminishes if drug therapy is not given promptly. In a previously reported case,2 a lab worker working with an attenuated specimen of the pathogen developed flu-like symptoms and eventually died of septic shock. The lab worker may have been lax in wearing gloves and other infection control measures when handling the specimen, the CDC reported.
Thus, it is understandable that workers at the Colorado State University Veterinary Teaching Hospital in Fort Collins, CO, were highly concerned to find out they had been exposed to Y. pestis — in many cases days after the fact.
Moreover, the dog had pneumonic plague, the most transmissible form of the infection, which is listed by the CDC as a possible bioterror agent because of the possibility of spread through the air via droplets.3
Clinicians missed the initial diagnosis of the infected dog, which then exposed dozens of hospital staff in transport throughout the facility, says lead author of the report Paula Schaffer, DVM, a pathologist and professor at the vet hospital in Fort Collins.
A scramble began when the dog’s plague infection was belatedly recognized, with many staff members contacted for post-exposure prophylaxis.
“Misdiagnosis in the canine patient exposed a lot of people to a serious disease — this was the biggest concern,” Schaffer says. “Plague is treatable with antibiotics in animals and people when the diagnosis is made early. However, once the disease progresses, it can be very hard to treat successfully. This was very concerning for our staff. Fortunately, we had no reports of illness related to exposure.”
Schaffer and colleagues reported1 that “While PCR results [for the dog] were pending, paper sheets were circulated to personnel to record contact with the dog. After the positive PCR result, emails were sent to these persons, followed by emails to all personnel.”
They added that “The delay between suspicion and diagnosis of Y. pestis resulted in word of mouth traveling faster than official communication, which caused anxiety among personnel. Many expressed frustration that suspicion and diagnosis of plague did not occur earlier. Two hospitalwide meetings were held for questions, discussion, and feedback.”
The communication process for zoonotic exposures at the hospital was set up to handle small-scale events, and was found lacking in this case, investigators said. The facility is now frequently updating email and phone lists and using a computerized log to document contacts that may be zoonotic exposures.
Employee fears were well-founded based on this information by the World Health Organization (WHO), which still sees bubonic and pneumonic plague appearing in some human populations.
“Pneumonic plague, or lung-based plague, is the most virulent form of plague,” the WHO reports.3 “Incubation can be as short as 24 hours. Any person with pneumonic plague may transmit the disease via droplets to other humans. Untreated pneumonic plague, if not diagnosed and treated early, can be fatal.”
Those exposed in Colorado included 64 hospital employees, 35 veterinary students, and 17 other employees and students in laboratory roles, Schaffer says.
Treatment recommendations included antimicrobial prophylaxis for those with highest concern for exposure (59% of total cases). Overall, one-third of the 116 people were also under fever and symptom watch.
Prior to admission, the dog had been seen near a dead prairie dog — an animal reservoir of the pathogen via fleas — but did not have classic signs of the plague, such as enlarged lymph nodes.
- Schaffer PA, Brault SA, Hershkowitz C, et al. Pneumonic Plague in a Dog and Widespread Potential Human Exposure in a Veterinary Hospital, United States. Emerg Infect Dis 2019;25(4):800-803.
- CDC. Fatal Laboratory-Acquired Infection with an Attenuated Yersinia pestis Strain — Chicago, Illinois, 2009. MMWR 2011;60(7):201-205.
- WHO. Plague fact sheet. Available at: https://bit.ly/2YvVI6V.