According to a statement from Jefferson County Public Health (JCPH), the infected squirrel was found in the town of Morrison, just west of Denver.
"Plague is an infectious disease caused by the bacteria Yersinia pestis, and can be contracted by humans and household animals if proper precautions are not taken," the statement read in part.
Specifically, humans can be infected by the fleas that bite the animals and then bite humans, passing the pathogen on to them.
Indeed, it was fleas biting infected animals -- in this case, rats -- and then humans that was responsible for the spread of the bubonic plague in Europe in the Middle Ages. Now sometimes colloquially referred to as "The Black Death," an outbreak of the plague in the region in the 14th century has been estimated to have killed 75 million-200 million people; by some estimates, roughly one third of the population of Europe at the time.
Humans can also be infected with the disease from direct contact with infected animals, such as through a cough or a bite.
Household pets are also at risk of contracting the disease, cats in particular. Cats sometimes enjoy eating rodents, such as squirrels, and a cat can pick up the disease by eating an infected rodent. They can also contract the disease through being bitten or scratched by an infected animal. A cat who contracts the disease can die quickly if not properly treated.
Dogs can also catch the disease, although health officials say they're less likely to get it.
Fortunately, the disease is easily treatable -- in humans and in pets -- with modern antibiotics.
Health officials say that any pet owner who sees symptoms of the plague in their animals should contact a veterinarian immediately.
"Symptoms of plague may include sudden onset of high fever, chills, headache, nausea and extreme pain and swelling of lymph nodes, occurring within two to seven days after exposure. Plague can be effectively treated with antibiotics when diagnosed early," the statement read.
Similarly, the statement noted that any humans who experience these symptoms should consult a physician immediately.
Meanwhile, authorities are asking the public to take simple precautions. Those include eliminating sources of food and shelter for wild animals around the home, not feeding wild animals, and maintaining proper flea and tick control of household pets, among others.