If you’ve seen a mouse crawling around your home lately, they’re not as innocent as they look. This year, we’re likely to see more cases of Lyme disease, which is marked by symptoms of a red rash and fever, and transmitted by mice.

In a map published in 2016 by the Centers for Disease Control and Prevention, the number of confirmed and probable Lyme disease cases in the U.S. more than doubled since 2001.

“We’re anticipating 2017 to be a particularly risky year for Lyme,” Rick Ostfeld, an ecologist at the Cary Institute of Ecosystem Studies, told NPR.

The number of Lyme disease cases since 2001 has more than doubled.

One reason the disease has spread quickly is climate change. Recently, President Donald Trump’s administration proposed defunding the National Oceanic and Atmospheric Association, which gathers research crucial to understanding the climate and weather. This is just one of many recent controversial policy proposals on climate change.

Another factor in the spread of Lyme disease is habitat destruction, which has decreased the population of foxes, hawks, and owls and increased the population of mice. Mice infect up to 95 percent of ticks that suck their blood. In fact, most of the ticks carrying Lyme disease in the northeast were infected by mice.

In the 1980s, Lyme disease cases were only confined in western Wisconsin and the area from Connecticut to New Jersey, but now the disease has spread in all directions. But since the 1990s, reported cases of Lyme disease have tripled to 30,000 cases a year. This is a probably a lower number than it actually is, the CDC says.

In 2001, Lyme disease cases were concentrated in the Northeast and parts of Wisconsin.

In 2015, the CDC reported that more than 95 percent of Lyme disease cases were reported from 14 states, mostly down the East coast and also in some areas of the Midwest and West Coast. Another reason for the spread of Lyme disease is the surge in deer. Now, forests of the Northeast are full of infected ticks, putting people in danger of Lyme.

To prevent yourself from getting infected, routinely check your body for ticks. If you do find a tick, get it off as quickly as possible. The longer an infected tick stays on your body, the higher the chance you have of getting Lyme disease. It usually takes 24 hours for a tick to infect someone after it bites. If you have any symptoms, see a doctor immediately.

Here’s the CDC’s full map:

Photos via Centers for Disease Control and Prevention