There are concerns after fleas in the US tested positive for the plague, the infamous infectious disease that killed millions of people during the Middle Ages.

On Friday Navajo County Public Health officials confirmed fleas in the region were testing positive for the disease and issued a public health warning to those in Arizona.

Officials have notified the residents whose property will be treated. The area will be closely monitored to determine if further action is required.

"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.

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The disease can be transmitted to humans by the bite of an infected flea or direct contact with an infected animal.

The plague claimed 100million lives worldwide when it struck during the 14th century.
The plague claimed 100million lives worldwide when it struck during the 14th century.

Symptoms of the plague include tender and painful lymph nodes, chills, fever, headache, weakness, and fatigue.

The news comes after three people needed hospital treatment after contracting the plague in New Mexico in June.

The US Center for Disease Control says there are an average of seven infections a year in the US.

In 2015 three people died after contracting the disease.

The plague is curable with proper antibiotic therapy if diagnosed and treated early.