What to know about the pneumonic plague after Arizona patient’s death

A person has died of the pneumonic plague at the Flagstaff Medical Center in Arizona, according to Northern Arizona Healthcare, the organization that runs the hospital.

The patient arrived at the emergency department and died the same day, a spokesperson for the organization said in an e-mailed statement. Coconino County, which includes Flagstaff, said it received test results confirming the patient’s condition a little over a week ago. The patient was a county resident, it said.

Here’s what to know about the pneumonic plague, a rare illness related to the bubonic plague.

The plague is an infectious disease caused by the bacteria Yersinia pestis. There are three common forms of plague: bubonic, pneumonic, and septicemic.

The bubonic plague, the most well known, killed tens of millions of people in Asia and Europe in the 14th century in a pandemic known as the Black Death. In the public imagination it is often thought of as a medieval disease, but it still exists — in a far more manageable context thanks to modern antibiotics.

Bubonic plague involves an infection of the lymph nodes, while pneumonic plague affects the lungs and septicemic plague the blood. The types can coexist if the bacteria spreads within the body after an initial infection.

Pneumonic plague is the only form that can be spread from person to person, rather than animal to person, through airborne droplets, according to the Centers for Disease Control and Prevention. But this has not been documented in the United States since 1924. Slightly more common is airborne infection from sick animals.

The pneumonic form is also the deadliest: It is always fatal when left untreated, according to the World Health Organization. The bubonic plague, the most common type, has a fatality rate of 30-60%.

All forms of the plague are rare. In the U.S. this century there have been an average of seven cases reported each year, according to the CDC, and fewer than that number of deaths.

Most human cases are acquired in rural parts of the western U.S. — specifically northern New Mexico, northern Arizona, southern Colorado, California, southern Oregon, and far western Nevada — where it became entrenched in rodent species. The disease can be transmitted to humans from animals via flea bites or through direct human contact with an infected animal, which can include pet dogs and cats.

Globally, plague is found in animals on every continent except Oceania, while human cases since the 1990s have mostly occurred in Africa, according to the WHO. The three most endemic countries are the Democratic Republic of Congo, Madagascar, and Peru, it says.

The bubonic plague is known for its dramatic boils, called “buboes,” caused by lymph nodes swollen with multiplying bacteria.

But these are not necessarily present for the pneumonic plague. Patients develop fever, headache, weakness, and a rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery mucus, according to the CDC.

Septicemic plague symptoms can include chills, abdominal pain, shock, bleeding into the skin and other organs, and skin and tissue turning black and dying.

There is no vaccine for the plague available in the United States, the CDC says.

It is easily treated with antibiotics, the WHO says, though it is vital to seek treatment as early as possible. The incubation period for the pneumonic plague can be as short as one day, and two to eight days for the bubonic type.

“Pneumonic plague can be fatal within 18 to 24 hours of disease onset if left untreated,” the WHO warns.

Health experts also recommend preventive measures such as wearing insect repellent and using flea control products on pets, rodent-proofing houses, and wearing gloves if it is necessary to handle a sick animal.

Adela Suliman contributed to this report.