A squirrel in Colorado has tested positive for the bubonic plague, county health officials revealed.

Over the weekend, officials from Jefferson County Public Health (JCPH) announced that the squirrel is the first case of the plague in the county, which is 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,” officials from Jefferson County Public Health (JCPH) wrote in a public statement.

The health department said humans can be infected through bites from infected fleas, by cough from an infected animal or direct contact — like through a bite — with the blood or tissues of infected animals.

As for household pets, cats and dogs are both at risk, however, the former are “highly susceptible and may die if not treated with antibiotics.”

“Cats can contract plague from flea bites, a rodent scratch/bite or ingestion of a rodent,” officials said. “Dogs are not as susceptible to plague; however, they may pick up and carry plague-infected rodent fleas.”‘

“Pet owners who suspect their pets are ill should consult a veterinarian,” they added. “All pet owners who live close to wild animal populations, such as prairie dog colonies or other known wildlife habitats, should consult their veterinarian about flea control for their pets to help prevent the transfer of fleas to humans.”

JCPH said the risk of contracting plague is “extremely low” if safety precautions are taken. (See the list of recommended precautions, here.)

According to the Center for Disease Prevention (CDC), symptoms of plague may include sudden onset of high fever, headache, chills, nausea, and weakness and extreme pain of one or more swollen lymph nodes (called buboes) and will occur within two to six days after exposure.

Unlike the novel coronavirus (COVID-19), the bubonic plague can be effectively treated with antibiotics.

However, in the pre-antibiotic era (1900 to 1941) the mortality rate in the US was 66 percent. Fortunately, after the discovery of antibiotics, the mortality rate decreased to 11 percent.

The CDC said there is now only an average of seven human cases of plague per year. Worldwide, there are between 1,000 to 20,000 cases each year, with a mortality rate of 8 to 10 percent, according to the World Health Organization (WHO).

Historically, the plague is one of the deadliest diseases, the most famous outbreak being what was known as the “Black Death,” named after the black skin sores that appeared on those infected with bubonic plague.

“Arguably the most infamous plague outbreak was the so-called Black Death, a multi-century pandemic that swept through Asia and Europe,” according to National Geographic. “It was believed to start in China in 1334, spreading along trade routes and reaching Europe via Sicilian ports in the late 1340s. The plague killed an estimated 25 million people, almost a third of the continent’s population. The Black Death lingered on for centuries, particularly in cities. Outbreaks included the Great Plague of London (1665-66), in which 70,000 residents died.”

Earlier this month, China reported a suspected positive case of bubonic plague in a farmer in the country’s Inner Mongolia region.