It has since been confirmed that the patient’s death was caused by pneumonic plague, which is a severe lung infection caused by the Yersinia pestis bacterium.

A recent pneumonic plague death in Northern Arizona, the first since 2007, has raised concerns about this rare but deadly disease. Caused by Yersinia pestis, it affects the lungs and spreads through respiratory droplets or from untreated bubonic/septicemic plague.

An Arizona resident has died from the plague as officials were probing whether a prairie dog die-off in the area was also tied to the lethal illness.