On Friday, health officials announced that a resident of northern Arizona has died from pneumonic plague, according to the Associated Press.

Federal health authorities noted that plague rarely affects humans, with the U.S. averaging about seven cases per year, mostly occurring in the western states. Local officials stated that the death in Coconino County — which includes the city of Flagstaff — is the first recorded fatality from pneumonic plague in the area since 2007.

Further details, including the identity of the victim, have not been disclosed.

Plague is a bacterial infection that killed tens of millions in Europe during the 14th century. Today, it can be effectively treated with antibiotics. The most common form is bubonic plague, which spreads naturally among rodents such as prairie dogs and rats. There are two other forms: septicemic plague, which spreads throughout the body, and pneumonic plague, which affects the lungs.

Pneumonic plague is the deadliest and most easily transmissible form. The bacterium is typically spread through the bites of infected fleas, which can transmit it between rodents, pets, and humans. It can also be contracted through contact with infected bodily fluids. Health experts advise extreme caution when handling dead or sick animals.

According to the Centers for Disease Control and Prevention (CDC), most plague cases in the U.S. occur in rural parts of northern New Mexico, northern Arizona, southern Colorado, California, southern Oregon, and the far western region of Nevada.