Fleas are testing positive for the plague in parts of Arizona

— -- Officials in two Arizona counties are warning the public after fleas in the region tested positive for the plague, the infamous infectious disease that killed millions during the Middle Ages.

Navajo County Public Health officials confirmed on Friday that fleas in the area have tested positive for the rare disease. The public health warning follows a similar notice from Coconino County Public Health Services District in Arizona warning of the presence of plague in fleas found there too.

Both counties are situated in the northern part of Arizona.

"Navajo County Health Department is urging the public to take precautions to reduce their risk of exposure to this serious disease, which can be present in fleas, rodents, rabbits and predators that feed upon these animals," the public health warning states. "The disease can be transmitted to humans and other animals by the bite of an infected flea or by direct contact with an infected animal."

Officials also urged persons living, working, camping or visiting in these areas to take precautions to reduce their risk of exposure, including avoiding sick or dead animals, keeping pets from roaming loose, and avoiding rodent burrows and fleas.

While the warning may ring alarm bells for people who only know of the plague from history books, the findings are not without precedent.

The Centers for Disease Control and Prevention (CDC) notes that studies suggest that outbreaks of the plague occasionally occur in southwestern U.S. states like Arizona during cooler summers that follow wet winters.

Symptoms of plague include sudden onset of fever, headache, chills, and weakness and one or more swollen, tender and painful lymph nodes, according to the CDC. If untreated, the bacteria can spread to other parts of the body.