A Northeastern University public health expert says the recent death of an Arizona resident from pneumonic plague underscores the severity of the rare disease as well as the need to seek treatment right away.
There are three types of plague, bubonic, septicemic and pneumonic. The Arizona victim had the more fatal pneumonic type, says Neil Maniar, director of Northeastern’s master of public health program.
The bubonic type, the more common type of plague named for the buboes or swollen lymph nodes experienced by sufferers, can be very severe with a case fatality ratio of 30% to 60%, according to the World Health Organization.
But the pneumonic type is nearly always fatal when left untreated, WHO says. The good news, Maniar says, “is today we have a way, with very effective antibiotics, to treat it.”
That wasn’t the case when the bubonic plague known as the Black Death killed at least one-third of the population of Europe in the 1300s.
“Part of why the 14th-century plague killed so many people was because we didn’t have a way to treat it,” Maniar says.
The current risk of contracting bubonic plague is so low that the Centers for Disease Control and Prevention reports seven cases a year, mainly in the semi-arid Western regions of the U.S., which witnessed 15 deaths from the disease from 2000-2023.
Entrenched in rural rodent populations in Arizona, New Mexico, Colorado and California, southern Oregon and northern Nevada, bubonic plague is most often transmitted by the bite of a flea infected with the Yersinia pestis bacterium.
Humans can become infected when handling an infected animal, such as when a hunter skins a rabbit without gloves, the CDC says.
The federal health agency says pneumonic plague develops when bacteria spreads to the lungs of a person with untreated bubonic plague or untreated septicemic plague, which is when symptoms include abdominal pain, shock and blackening of tissues on the fingers, toes and nose.
People and animals with pneumonic plague can also transmit the bacteria via cough droplets in the air. The CDC says person-to-person transmission was last documented in the U.S. in 2024.
Cats are particularly susceptible to plague from eating infected rodents, and there have been rare cases of felines transmitting the plague to humans, the federal health agency says.
However, when bubonic plague is contracted, treatment time is of the essence — especially for pneumonic plague, Maniar says.
Left untreated, pneumonic plague can turn fatal within 18 to 24 hours of onset, the WHO says. Symptoms of the pneumonic version of the disease include fever, headache, weakness and rapidly developing pneumonia with shortness of breath, chest pain, cough and bloody or watery mucus, the CDC says.
“Individuals who live in areas where there may be a risk for this, even though the risk is very small, should be on the lookout for signs and symptoms,” especially if they think they may have come into contact with infected animals, Maniar says.
“If you suspect you have symptoms, seek health care immediately, because there’s very effective treatment,” he says. “Any loss of time in treatment can make a big difference in severity and potential risk of death.”