Two exceptions to the rule – bubonic plague not from rat fleas, but from a pet dog; and possible human to human transmission – the first in USA in 90 years.
As a former laboratory manager I was mindful of the “rare ones” i.e. identifying diseases that are exotic or rarely seen – or more importantly, missing the diagnosis. More so if the disease is communicable.
In a recent CDC MMWR, Runfola, House, Miller, et al. published such an event occurring in Colorado.
The index patient was admitted to hospital ill with fever and cough, worsening to pneumonia. A lab culture automatedly misidentified the pathogen as Pseudomonas luteola but as the patient’s condition worsened, the culture was sent to the state lab and correctly identified as Yersinia pestis, the cause of bubonic plague.
Investigation revealed the dog had recently died, and three persons who had contact with the dog were found to be ill, two with pneumonia. One of the three had contact with the index patient and human to human transmission could not be ruled out. Two of the cases were veterinary employees who euthanized the ill dog.
In total, 114 people were investigated as they had contact with the dog or the index patient. No other cases were detected and the four patients recovered with appropriate therapy.
Untreated Bubonic plague (the “Black Death”) can be fatal in 93% of cases and although the initial laboratory misidentification resulted in occult exposure to numerous healthcare workers, an astute physician and rapid investigation resulted in zero fatalities in this outbreak.
The lesson: double-check organism identification if patient has plague-like symptoms (this is third time Y. pestis has been mistaken for P. luteola).
PS. I returned home this week from Sierra Leone and will write an “update” post asap.