Pneumonic Plague in an Era of COVID-19

During an outbreak, normal aspects of health and public health can fall to the wayside. Now consider a pandemic. Perhaps one of the biggest concerns we, as infection preventionists and epidemiologists, had during the first 6 months of the COVID-19 pandemic, was “what about everything else? How will avoid losing sight of all the other infectious disease issues we face?”

From healthcare-associated infections to the day-to-day infectious disease threats we face, prevention and response becomes increasingly challenging during a global pandemic. That seems obvious though, right? There’s been growing discussion and presentation of the impact the COVID-19 pandemic had to public health response for non-COVID issues, such as vaccine-preventable diseases.

It will likely take years for us to understand the impact COVID-19 had on public health prevention and response, but as these examples trickle in, it will be critical to take the lessons learned. One such example is pneumonic plague. Consider how we might handle a non-COVID respiratory disease during the pandemic?

That’s exactly what happened to the Wyoming Department of Health (WDH) in September of 2021. While plague isn’t totally unknown in the United States—it’s endemic in the Four Corners [this is a region of the Southwestern United States consisting of the southwestern corner of Colorado, southeastern corner of Utah, northeastern corner of Arizona, and northwestern corner of New Mexico]—at this point in the pandemic, it felt like if something wasn’t COVID-19 we didn’t stress.

This particular review from the Centers for Disease Control and Prevention (CDC) Morbidity and Mortality Weekly Report (MMWR) reviewed the patient’s onset, negative SARS-CoV-2 antigen test, lack of travel, and interacting with two pet cats who were sick. Hospitalized for worsening symptoms and lung imaging that pointed to community-acquired pneumonia, the patient also had a respiratory panel that was negative for common viral pathogens.

“Within 48 hours of admission, the patient required mechanical ventilation and developed sepsis. The patient was treated for pneumonia and sepsis with azithromycin, piperacillin-tazobactam, and vancomycin. Seventy-two hours after the patient was admitted to the hospital, blood and sputum cultures did not indicate a causative pathogen. Because of the patient’s history of exposure to cats that were ill, an infectious diseases specialist recommended repeating a sputum culture with Gram stain and empiric treatment with ciprofloxacin. Gram-negative bacilli were detected, and the Wyoming Public Health Laboratory subsequently confirmed Yersinia pestisas the pathogen.”

The WDH worked to identify close contacts, review local animal control and state reports, but also assess the individual’s place of residence from an environmental perspective. Ultimately, it was found that twenty-two close contacts were identified, all received post-exposure prophylaxis (PEP) within 1 week of the patient’s symptom onset. Moreover, despite the death of one of the cats with an onset of respiratory symptoms, serologic testing was negative for Y pestis.

Overall, this case and report are an important reminder of how we approach respiratory illness during a pandemic of respiratory illness. For the past 2.5 years, the sentiment has been very COVID-focused, which can easily dissuade further pursuit of non-COVID issues after it’s been ruled out.

As the authors noted, “Overlooked diagnoses of rare pathogens can lead to significant consequences. This investigation highlights challenges associated with diagnosis and treatment of an illness from a rare pathogen whose symptoms mimic those of a pandemic illness, in this case, COVID-19. Timelier diagnosis might have resulted in initiation of effective antibiotic treatment closer to disease onset and decreased illness severity and hospitalization.”