Officials with the Coconino County Public Health Services District confirmed that fleas collected near the urban trails southeast of Interstate 40 and Butler Avenue and west of Herold Ranch Road in Flagstaff tested positive for plague.
The fleas were found in prairie dog burrows in the area.
The tests were conducted by the Center for Microbial Genetics and Genomics at Northern Arizona University.
The health department posted signage in the infected area and the burrows have been treated. The area will be closely monitored to determine if further action is required.
To limit possible exposure, residents and visitors are encouraged to avoid rodent burrows in the area and keep dogs on a leash as required by state law.
This positive test is the first evidence of plague activity reported in the county this year. The disease is not uncommon to locations throughout the county, however, and may be more widespread.
The health district is urging the public to take precautions to reduce their risk of exposure to this serious disease, which can be present in rodents, rabbits, and sometimes predators that feed upon these animals. 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.