Last summer Felicia Keesing returned from a long trip and found that her home in upstate New York had been subjected to an invasion.
“There was evidence of mice everywhere. They had completely taken over,” says Keesing, an ecologist at Bard College.
It was a plague of mice. And it had landed right in Keesing’s kitchen.
“Not only were there mouse droppings on our countertops, but we also found dead mice on the kitchen floor,” says Keesing’s husband, Rick Ostfeld, an ecologist at the Cary Institute of Ecosystem Studies in Millbrook, N.Y.
The Hudson River Valley experienced a mouse plague during the summer of 2016. The critters were everywhere. For most people, it was just a nuisance. But for Keesing and Ostfeld, the mouse plague signaled something foreboding.
“We’re anticipating 2017 to be a particularly risky year for Lyme,” Ostfeld says.
Keesing and Ostfeld, who have studied Lyme for more than 20 years, have come up with an early warning system for the disease. They can predict how many cases there will be a year in advance by looking at one key measurement: Count the mice the year before.
The number of critters scampering around the forest in the summer correlates to the Lyme cases the following summer, they’ve reported.
The explanation is simple: Mice are highly efficient transmitters of Lyme. They infect up to 95 percent of ticks that feed on them. Mice are responsible for infecting the majority of ticks carrying Lyme in the Northeast. And ticks love mice. “An individual mouse might have 50, 60, even 100 ticks covering its ears and face,” Ostfeld says.
So that mouse plague last year means there is going to be a Lyme plague this year. “Yep. I’m sorry to say that’s the scenario we’re expecting,” Ostfeld says.
He’s not exactly sure which parts of the Northeast will be at highest risk.
But wherever Lyme exists, people should be vigilant, says epidemiologist Kiersten Kugeler at the Centers for Disease Control and Prevention.
“Whether it’s a bad season or not, there’s still going to be a lot of human cases of tick-borne diseases,” she says. “What’s important for people to know is that the ticks are spreading to new areas — and tick-borne diseases are coming with them.”
Back in the early ’80s, the disease wasn’t that big a problem. Cases were confined to two small regions: western Wisconsin and the area from Connecticut to New Jersey.
Since then, Lyme cases have shot up in number and spread in all directions: “The only place that they haven’t really spread is into the Great Lakes and the Atlantic Ocean, for obvious reasons,” says biologist Rebecca Eisen, who’s also at the CDC.
Now Lyme is present in more than 260 counties, the CDC reported in 2015. The disease shows up in Maine, swoops down the East Coast into Washington, D.C., and southern Virginia. Then it hops to the Midwest into northern Indiana, Illinois, Wisconsin and Minnesota. There are also small pockets of Lyme on the West Coast.
How Lyme Disease Cases Have Spread In The U.S.
The number of confirmed and probable Lyme disease cases in the U.S. more than doubled from 2001 to 2015. In 2015, 95 percent of confirmed cases were reported in the 14 states labeled below.
And that means people, in some areas, may be putting themselves at risk for Lyme every single day without even knowing it, says the CDC’s Kiersten Kugeler. “In the Northeast, most people catch Lyme around their homes,” she says. “People out gardening. People playing in their backyard. Mowing the lawn.”
So what can you do to keep from getting infected? Add a tick check to your daily routine, Kugeler says. When you’re in the shower check your body for tiny ticks, especially the places they like to hide.
“That’s the scalp, behind the ears, the armpits and in the groin area,” she says.
If you do find a tick, get it off as quickly as possible. The longer an infected tick stays on your skin, the greater the chance it will pass the Lyme bacteria on to you. Generally, it takes about 24 hours for the tick to infect a person after it starts biting.
Then be on the lookout for Lyme symptoms — like a red rash or a fever. It anything crops up, go see a doctor immediately. Don’t wait: The earlier you get treated, the better chance you’ll have for a full recovery.