Prairie dogs living in a colony near Broomfield’s Great Western Reservoir Open Space are the first 2017 victims of plague in Colorado.

Broomfield Public Health and Environment reported the incident March 17 following a prairie dog die-off.

The city posted signs near the open space listing precautionary measures, but we thought it would be a good time to review how plague spreads and how you can keep yourself and your animals safe this spring and summer.

We talked to Jennifer Chase, the disease intervention program manager for the Tri-County Health Department, about the disease.

What is the plague?

Plague is an illness caused by a bacterium. Humans and other mammals like dogs, cats and prairie dogs can catch it.

How is it spread?

You and your pets can catch it from handling other infected animals and from the fleas that live on infected animals.

Fleas are hosts for the plague, which means they’re infected with the disease but it doesn’t harm them the way it does mammals.

Chase also mentioned that outdoor cats were more likely to catch the disease than dogs.

How many human cases have there been in Colorado?

Plague in humans is rare in Colorado. The state reported zero human cases in 2016, four in 2015 and eight in 2014. Two of those people infected in 2015 died.

Nationally, the Centers for Disease Control records an average of seven cases of human plague per year.

As for fatalities, the CDC recorded only four U.S. deaths from plague in 2015, none in 2014 and one in 2013. A total of 11 people died from 2005 to 2015.

For comparison, 17 people died from lightning strikes in Colorado alone during that same 10-year period.

OK it’s rare, but how deadly is it if you catch it?

The plague was lethal in Europe during the Middle Ages, “but now it’s different. We have a lot fewer cases in humans,” Chase said.

And we have antibiotics to treat the illness if you do happen to catch it.

The deadliness of the disease depends on which strain you have.

The most common is the bubonic plague. Chase said this strain is treatable with antibiotics.

Septicemic plague is when the bacteria enters the bloodstream. This is a rare but serious form of the plague and is usually fatal without treatment.

And then there’s pneumonic plague, which is when the bacteria gets in your lungs.

“That is almost always fatal if it’s not treated right away,” Chase said.

How do I know if I have plague?

The symptoms can start like a regular cold with fever, chills, swollen lymph nodes and a headache that appear one to six days after being exposed.

The more serious strains cause symptoms like weakness, vomiting blood and a red and/or black patchy rash.

It’s important to tell your doctor if you’ve been hiking or live near a prairie dog colony – especially if your dog or cat got sick before you did, Chase said.

Are the elderly, small children or pregnant women more vulnerable?

Since the number of plague cases is so small each year, Chase said there’s no data on whether the disease is more harmful to specific populations.

What can I do to protect my family and pets?

You can use insect repellent when you hike and treat your outdoor pets with flea medication or flea collars.

You can also wear long pants and tuck your pant legs into your socks.

“You should never come into contact with [prairie dogs], and try to stay out of the colonies.” Chase said.

And keep an eye on your dog or cat when they’re out in case they encounter a sick or dead animal.