The infectious disease that killed millions during the Middle Ages has been found again in Arizona.

Fleas in Navajo County have tested positive for the plague, KTVK reported. One week ago, fleas on prairie dogs in Coconino County tested positive for the disease.

Properties are set to be treated and officials will monitor the region to see if they need to take additional steps.

According to the Centers for Disease Control and Prevention, the plague is caused by Yersinia pestis. Normally people get the illness from being bitten by a rodent carrying the bacteria or by handling an infected animal. Antibiotics can treat the illness, but without prompt treatment it can cause serious illness or death.

There are three types of plague that doctors can watch for: bubonic plague, septicemic plague and pneumonic plague. In all types, patients can have fever, headache, chills and weakness.

For more on the specific symptoms, depending on the type of plague, click here.

File photo

Credit: Handout

icon to expand image

Credit: Handout