Deer ticks will rebound quickly in Pennsylvania after cold weather, experts say
Joyce Sakamoto, a Penn State University research associate in entomology, wanted to see for herself whether the harsh winter has taken a toll on the state's tick population.
“So when temperatures reached over 30 degrees, I went out to check out a couple of tick hot spots nearby (State College) to confirm,” Sakamoto said.
“If it was going to kill, then it should have, but it didn't. When it warms up ... even to 30 degrees, these guys come up. ... I collected 80 specimens at one of the sites,” said Sakamoto, who studies tick biology.
In 2016, Pennsylvania led the nation with more than 12,000 confirmed cases of Lyme disease, which is transmitted to humans from the bite of the black-legged or “deer” tick.
In January, the state Department of Conservation and Natural Resources reported that this year's frigid cold, combined with fluctuating temperatures, could reduce the state's tick population by more than 20 percent. Controlled lab experiments, using freezers, show that ticks will die between minus 2 and 14 degrees Fahrenheit, according to the report.
But lab conditions aren't the same as nature, other experts say, and the number of survivors could be considerably higher.
“Black-legged ticks are extremely hardy,” said Dr. Thomas W. Simmons, an Indiana University of Pennsylvania biology professor.
Simmons co-authored a study in 2015 with collaborators from the state Department of Environmental Protection that revealed that ticks had expanded into all of Pennsylvania's 67 counties.
“That estimate (of 20 percent of the tick population dying) was just an educated guess. But with all the fluctuations in temperatures we've had this winter, it may approach that,” Simmons said.
Simmons said Sakamoto's findings shouldn't surprise anyone.
“Ticks literally make their own antifreeze protein that protects them from the cold. And if there's snow cover, just forget about it. ... They'll just burrow down under the insulation,” Simmons said.
Sakamoto said some of the specimens she collected Jan. 30 simply burrowed down into the leaf cover and into the soil.
“I will say that without snow cover and extreme cold temperatures, you could possibly see 10 to 20 percent reduction, but once the temperatures start rising in the spring ...
“You won't even notice any difference when they start coming up looking to latch on to a host,” Simmons said.
Sakamoto added that despite the danger ticks present, “people shouldn't be paranoid about getting out and enjoying the outdoors.”
“You've just got to be aware. Don't be lax,” she said.
Nate Wardle, emergency preparedness public information officer with the state Department of Health, said that even though risk for Lyme disease is lowest in December through March, people should protect themselves from tick bites.
“Anyone spending time outdoors should take steps to prepare themselves, no matter the season. Most ticks are not active once temperatures are below freezing, but if temperatures warm, it is a good reminder that ticks prefer warm spots on the body,” Wardle said.
The first line of defense is for people to wear long sleeves and pants and insect repellent with DEET, he said.
After being outdoors, people should check for ticks and shower to help ensure an insect hasn't embedded itself, Wardle said.
“Anyone who is bitten should remove the tick. They should then monitor the area, and if symptoms of Lyme disease develop, consult with a physician,” he said.
Symptoms include a bull's-eye rash near the site (which doesn't always occur), fever, fatigue, headaches, muscle aches and joint pain.