Montezuma County Health officials were on high alert recently after a few prairie dogs turned up dead, which sometimes could be related to the plague.
Melissa Mathews, health inspector for the county, said the concern caused the department to post warnings, telling residents to be careful around prairie dogs populations.
While prairie dogs cannot transmit the plague to others, the fleas on the burrowing rodent can lead to infections of people or animals.
After further investigation, the health department determined the dead prairie dogs actually had been struck and killed by vehicles and then thrown onto lawns from the pavement, so at first glance the cause of the deaths were an unknown.
While there have been no reported cases of plague in Montezuma County this year, a 7-year-old girl recently contracted the bubonic plague during a family outing at a campground northwest of Pagosa Springs. She contracted the disease from flea bites during a picnic. The girl is recovering at a Denver hospital.
This was the first confirmed case of the plague in humans in Colorado since 2006.
Mathews said seeing live prairie dogs can be considered a positive, when the alternative is seeing the rodents dying at an alarming rate for no apparent reason. Not seeing the rodents in the winter is common since that is when they hibernate.
While the ground squirrel is the most likely rodent to carry the plague, the enormous number of prairie dogs in the county causes health officials to monitor them closely.
According to the health departments website, plague is firmly entrenched among wild rodents in North America and individual cases continue to occur among humans exposed to the rodents and their fleas.
In Colorado, local health departments and county environmental health officers have training in plague surveillance and control. Their agencies should be contacted whenever there are observations, especially large-scale rodent die-offs that arouse suspicions about this disease.
Each rodent species is host to one or more species of fleas which, when infected, are carriers. These fleas generally do not infect other animals unless their natural hosts are unavailable.
Mathews said the report that a Colorado resident was recently infected should not be too surprising because plagues are all around this area in the wilderness.
It goes around every other day, she said.
Rock squirrels are closely related to California ground squirrels and are the most significant plague host in Colorado. This flea is an aggressive parasite and will readily bite other animals and people. Domestic cats and dogs can also contract plague by infected fleas. They may carry infected fleas home to their owners or, especially with cats, serve as a direct source of infection.
Mathews added the bubonic plague is what nearly wiped out Europe in the 1400s, and mentioned the bubo name comes from the definition of the swelling of the lymph nodes.
Even though the cases of plague are rare there are preventive steps that can be taken to make residents even safer.
Not playing with wild animals or touching dead animals where the infected fleas could still be present is a given.
Staying out of areas where there are mosquitoes/fleas is a good idea, she said, and using lots of insect repellent and tucking pants into socks to prevent fleas from making contact with the skin.
Mathews also recommends keeping pets on a leash and out of areas where fleas could reside, clearing debris from around homes and setting traps.
She said rodents typically like climates between 5,500 and 8,000 in altitude, and added hotter weather tends to kill off fleas, while mosquitoes prefer warmer weather.