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The new winter threat: how ticks are spreading Lyme disease

By Jake Beardslee · November 20, 2023

In brief…

  • Lyme disease cases rising in winter due to climate change and warmer temps
  • Ticks remaining active in spots with warmer microclimates
  • Adult ticks more likely to transmit Lyme, but easier to detect and remove
  • Prompt tick removal key to reducing infection risk
  • Pet owners urged to stay vigilant with preventative measures
Climate change leads to increased risk of Lyme disease transmission by ticks during winter months.  Leroy Baptiste/Wikimedia

As winter approaches, health experts warn that tick season is no longer limited to the warmer months. Ticks are remaining active during winter due to climate change causing warmer temperatures, posing an increased risk of Lyme disease transmission year-round.

“Winters used to be more consistently cold,” said Rafal Tokarz, an epidemiologist at Columbia University, to NBC News. “Now we have stretches of abnormally warm weather and they come out more frequently.” Tokarz explains that on warmer winter days, more people venture outdoors with their pets, encountering questing ticks. This contributes to rising Lyme disease cases in winter, evidenced by increased ER visits for tick bites in parts of the U.S.

While adult ticks become less active in freezing temperatures, they can survive the winter months hunkered down until warmer days allow them to become active again. “The ticks will be there,” Tokarz said. “As soon as it gets warmer or a little sunny, they pop back out again.”

Ticks’ expanding geographical range also contributes to wintertime Lyme disease risk. Laura Goodman, an infectious disease researcher at Cornell University, warns that general winter forecasts aren’t helpful for gauging tick activity. “There can be spots where it feels warmer. Thinking about the general forecast is not that helpful in this situation.”

Prompt tick removal is key to reducing infection risk. Adult ticks have a higher likelihood of carrying Lyme-causing bacteria, but they are larger and easier to detect than tiny nymphs. Tokarz advises using repellent, wearing light clothing, and thoroughly checking for ticks after potential exposure. Ticks should be removed promptly and clothes dried on high heat.

Pet owners should also take precautions like Lyme vaccination for dogs, preventative tick medication, and vigilant tick checks. “You can never totally let your guard down,” Goodman stated.