Both are located in the northern part of the state.
#8216;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.#8217;
Navajo County Public Health officials confirmed on Friday that fleas in the region tested positive for the disease following similar reports from Coconino County Public Health Services District in Arizona.
It is caused by a bacterium known as Yersinia pestis, which uses the flea as a host and is usually transmitted to humans via rats.
The Bubonic plague killed millions during the Middle Ages