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Humans can contract the plague bacterium, Yersinia pestis, when bitten by a rodent flea that is carrying this pathogen, or by handling an infected animal. Murine typhus, due to Rickettsia typhi bacteria, can also be transmitted by rodent fleas to humans. (CDC)
Humans can contract the plague bacterium, Yersinia pestis, when bitten by a rodent flea that is carrying this pathogen, or by handling an infected animal. Murine typhus, due to Rickettsia typhi bacteria, can also be transmitted by rodent fleas to humans. (CDC)

Laboratory tests confirmed the presence of the plague in fleas collected in La Plata County after a 10-year-old girl died from the disease earlier this month, public health officials said.

The plague-positive fleas were collected from a private property in south central La Plata County after residents reported a nearby prairie dog colony had gone “silent” and that the activity of the animals was no longer visible, said Dr. Jennifer House, the Colorado Department of Public Health and Environment’s state veterinarian Monday. Health officials have not confirmed the girl who died was infected by fleas from the colony under investigation.

Health officials were notified of the potential case July 5 and days later, confirmed that the girl died from the plague — the state’s first human plague death since 2005. The Durango Herald reported that the fourth grader raised hogs in 4-H.

The Colorado Department of Public Health and Environment has reported plague cases in animals from across the state, though they are most commonly found in rural areas, House said. So far this year, plague has been detected in Adams, Boulder, Huerfano, El Paso, La Plata and San Miguel counties, she said. 

“We can honestly see plague in most locations. The majority of our positive animals come more from rural areas, but we have seen plague approaching the metro area,” House said, noting that in 2009, health officials saw a prairie dog die-off near the border of Denver and Adams counties.

Plague is found in animals and people year round in Colorado, though it is most commonly detected during the spring and summer months, after animals become more active and reproducing, House said. This is when there is also higher chances of people interacting with animals.

“There is no month where it is not present,” she said.

CDPHE is currently investigating several plague cases around the state, she said.

While prairie dogs are extremely susceptible to the disease, other rodents such as squirrels, wood rats and chipmunks, could also become infected and pose a risk to people, House said. 

Because prairie dogs are very visible animals and active during the day, people who live near their colonies may notice when there is less activity than normal, she said, explaining that’s an indication plague could be present.

If plague is suspected in an area, CDPHE will work with Colorado Parks and Wildlife to apply a pesticide treatment to the burrows to kill the fleas, she said. If the prairie dogs have already died, the pesticide will protect other animals who may pass near the colony and prevent them from transporting the fleas.

Plague has the potential to spread quickly, she said. 

A coyote peers out from cover in this 2014 photo taken at the Bear Creek Greenbelt in Lakewood. (Rob Raker, Special to The Colorado Sun)

“All it takes is one coyote or a fox to go through a rodent die-off area and pick up infected fleas to transport it to a different area,” Dr. House said. 

​​Residents should not kill prairie dogs on their property because doing so increases the risk of contracting the plague, the San Juan Basin Public Health Department warned in a news release.

While state data shows only four cases of confirmed plague in animals this year, House warned that the data is not completely reflective of plague in the state due to the challenges in testing.

“Even if you don’t see a lot of positives in our database, it doesn’t mean it isn’t present. It just means we weren’t able to find the correct specimen and conduct laboratory tests to get the results,” she said. “It is always going on undetected.”

According to the Centers of Disease Control and Prevention, between one and 17 cases of plague, on average, are reported annually in humans, with hot spots in northern New Mexico and Arizona, and in southern Colorado.

How to stay safe from the plague

Those who develop a high fever after they have been outdoors where they may have been bitten by a flea, or have touched a sick or dead animal should seek medical care immediately, House said. 

Symptoms of the bubonic plague, which is often transmitted by a flea bite, include a high fever, headache, chills and swollen lymph nodes, according to the CDC.

“Plague moves very quickly in the body. There are antibiotics that can successfully treat plague but they have to be started within 24 hours of the first symptom developing,” she said. 

To reduce the risk of contracting the plague, San Juan Basin Public Health suggested the following:

  • Protect pets with a flea treatment and keep them on a leash and out of wild rodent habitats.
  • Avoid sleeping alongside your pets.
  • Keep pets up to date on vaccinations and protected from fleas with flea collars and veterinary approved topical medications
  • Avoid all contact with rodents, including squirrels. Do not feed them.
  • Treat known rodent nests around your home with flea powder or an insecticide.
  • See a doctor if you become ill with a high fever and/or swollen lymph nodes.
  • Do not touch sick or dead animals
  • Contact a vet if your pet becomes ill with a high fever, open sores or swollen lymph nodes. Pets with plague can transmit the illness to humans.

Olivia Prentzel covers breaking news and a wide range of other important issues impacting Coloradans for The Colorado Sun, where she has been a staff writer since 2021. At The Sun, she has covered wildfires, criminal justice, the environment,...