Lyme disease, tick population spread

A Centers for Disease Control and Prevention chart depicts the size of blacklegged ticks in their lifecycle. The nymph stage is when ticks most frequently pass Lyme disease to humans.

TRAVERSE CITY — A growing public health problem lurks in some of northern Michigan's most picturesque places.

"We are seeing a general increase in ticks across the Lower Peninsula," said Howard Russell, an entomologist at Michigan State University. "Over the last four years, it's been pretty remarkable."

That increase, an exponential boom in the tick population in the past decade, has brought with it an explosion in the number of reported cases of Lyme disease, Russell said. 

He said three species of ticks are now commonplace in areas along the Lake Michigan shoreline, including American dog, lone star and blacklegged ticks. The latter is of greatest concern to Michiganders.

"That is the only tick that is known to transport Lyme disease," Russell said, adding that people can email pictures of ticks to him for expert identification, at bugman@msu.edu.

The Michigan Department of Health and Human Services now lists 18 counties on the western edge of the Lower Peninsula as "endemic" counties with known risk for Lyme disease transmission to humans. The department defines "endemic" as any county where laboratory tests confirmed there are infected ticks in those locations or at least two laboratory-confirmed cases of humans infected with Lyme disease have been reported.

Grand Traverse, Leelanau and Benzie counties all are on that list.

Jennifer Sidge is conducing doctoral research on the ticks' rapid invasion in Sleeping Bear Dunes National Park and said they appeared there five years ago. 

The Lower Peninsula was a safe-haven from ticks and the diseases they carry until sometime in the 1990s, Sidge said.

Then both ticks and Lyme disease began rearing their heads.

There have been more than 500 cases of Lyme disease reported in Michigan since 2009, a number Russell believes is underreported because the symptoms are similar to other illnesses and tests are required to confirm infection.

The DHHS received confirmed reports of 128 cases statewide in 2014, said Angela Minicuci, the department's communications director.

"It is slowly but surely spreading in toward the eastern side of the state," she said.

Russell doesn't know why ticks suddenly appeared where they hadn't been before. But he also doesn't know why they weren't there in the first place since the habitat in the Lower Peninsula is similar to other places in the Midwest where they are prevalent. 

The most likely time for humans to be exposed to Lyme-disease carrying ticks begins soon. The bugs are particularly likely to pass Lyme disease when they reach nymph stage — some no bigger than a pin head — a part of their life cycle that lasts from late June through late July.

They lay low in grassy areas, waiting for a host to pass through and brush against the foliage. The minuscule pests often pick up the disease from mice then pass it to humans, Russell said.

"Unfortunately, there is no real solution where we can stop the spread of ticks," Sidge said.

So state health officials have been trying educate the public on how to prevent infection, Minicuci said.

"One of the most important things people can do is perform pretty good tick inspections," Russell said. "Since you're looking for something the size of the head of a pin they need to be thorough."

The risk of contracting Lyme disease is significantly reduced if a tick is removed within 48 hours of when it first bites, he added.

Screenings of the film "Emergence," a documentary about people who caught Lyme disease, will take place June 25 at 7 p.m. followed by a discussion hosted by a local Lyme disease support group. The screening will take place at 610 Three Mile Road. Call 231-269-3406 for more information.

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