Disease-carrying ticks move deeper into NorthlandBlacklegged ticks continue to infiltrate the Arrowhead. "We are starting to see patients now (with) very well-confirmed diagnoses of Lyme disease who were right here in the immediate Duluth area or just up the North Shore,” said Dr. Linda Van Etta, infectious disease specialist for St. Luke’s hospital.
By: John Lundy, Duluth News Tribune
Blacklegged ticks continue to infiltrate the Arrowhead.
“It used to be that if you step south of Superior, Wis., or you go down on 35 toward Moose Lake in the sandy areas, you’re going to have a high risk, but if you go here in Duluth or north of Duluth, up the North Shore, you’re going to have less of a risk,” said Dr. Linda Van Etta, infectious disease specialist for St. Luke’s hospital.
“But we are starting to see patients now (with) very well-confirmed diagnoses of Lyme disease who were right here in the immediate Duluth area or just up the North Shore.”
Dr. Timothy Burke, infectious disease specialist at Essentia Health, agreed.
“A decade or so ago it was unusual to see a tick-borne illness diagnosed in someone from north of Duluth,” Burke said Friday. “But now it’s a fairly routine thing.”
Their observations are confirmed by a study in the February issue of the American Journal of Tropical Medicine and Hygiene. The Associated Press reported Friday that the study’s researchers created a detailed map showing areas of the East and Midwest where people have the highest risk of contracting Lyme disease. Those are the areas where the group of 80 researchers found blacklegged ticks, the insects also known as deer ticks. They can carry the bacteria that cause Lyme disease and five other diseases that can strike humans, Van Etta said.
On the map, most of Wisconsin is colored red, indicating high-risk areas. Some of eastern and north-central Minnesota also is shown in red, but the Arrowhead is largely excluded — except for a telltale streak of red along the North Shore.
Dave Neitzel, a Minnesota Department of Health epidemiologist who spends some of his time in the woods looking for blacklegged ticks, has seen the same thing.
“We’ve collected blacklegged ticks up through Lake County, and in just the last few years now we’re starting to get scattered records of ticks submitted by the public … that were collected all the way up into Cook County,” Neitzel said. “In the last couple of years we’ve confirmed blacklegged ticks all the way up to the Minnesota-Ontario border in the northeast and the Minnesota-Manitoba border in the northwest.”
In addition, tick-borne diseases have become more common in the Brainerd and Grand Rapids areas in the past few years, Neitzel said.
Minnesota had a record number of tick-borne illnesses in 2010, with 1,293 confirmed cases of Lyme disease and 720 cases of anaplasmosis. The numbers aren’t finalized for 2011, Neitzel said, but it appears they’ll be similar to the year before.
But it was a “robust” year for tick-borne illnesses at St. Luke’s, Van Etta said. “And people we work with, if they’re at their cabin by Hayward, in one evening they’d come in and they took off 35 ticks that night. Or one sent me a picture of his dog. It was just covered head to toe with ticks.”
Both Van Etta and Burke said a number of mild winters over the past 10 years might have enabled the blacklegged tick to expand its range.
But that doesn’t necessarily mean this year’s mild winter will produce a bumper crop of the ticks, said Jeff Hahn, an entymologist for the University of Minnesota Extension Service. The lack of snow cover might balance the mild conditions. The ticks burrow into organic matter, such as leaves, during the winter, he said. If there’s no snow, they don’t have much protection.
Last winter’s early heavy snow was ideal for ticks, Hahn said, because it gave them insulation before the ground was even frozen.
But there’s always reason to be cautious about blacklegged ticks in the Minnesota and Wisconsin woods, Hahn said. In fact, if there’s no snow, ticks can be active even in 40-degree weather. “I’m not going to say it’s a high risk for those mild days when it’s in the 40s,” he said, “but on the other hand it’s not impossible, either.”