Experts caution public leading up to peak season for Lyme disease

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Jonah Beleckis
Wednesday, May 10, 2017

JANESVILLE—Tick season is back, leading experts to caution the public on the dangers of Lyme disease.

Reported cases of Lyme disease rose substantially from 2000 to 2010 but then started to level out in the following five years, according to data from the state Division of Public Health.

By measuring probable cases since 2008 and estimated cases since 2012, officials are becoming more aware of just how widespread the disease can be.

Susan Paskewitz, an entomology professor and expert on Lyme disease at UW-Madison, said the number of Lyme disease cases could be as much as 10 times the reported number.

Paskewitz said researchers nationwide believe there could be an increase in the disease this year because of a larger mouse population. White-footed mice, which are “very important” to the disease, are a food source for immature ticks that carry Lyme disease and serve as a reservoir for the pathogen, she said.

Paskewitz said she did not see much evidence of such an increase across Wisconsin, however. She said there might be some communities seeing larger mice populations.

Lyme disease, first recognized in 1975, is transmitted to humans by a tick, often called the blacklegged or deer tick, according to the division's website. The disease often (but not always) begins as a roughly circular reddish rash near the bite site. Other symptoms include fever, headache, fatigue, stiff neck, muscle or joint pain and swelling.

Matthew Wesson, environmental health supervisor for Rock County, said it is “hard to say” if the Lyme disease increases he has seen statewide were due to more infected ticks or more awareness and better reporting.

“It's certainly a significant disease in the area,” Wesson said. “It's not going away anytime soon.”

Rock County has yet to see a confirmed Lyme disease case in 2017. There were 38 confirmed cases from 2012 to 2016, Wesson said.

Wesson emphasized not everyone who is diagnosed and/or treated has a confirmatory test.

About half of adult deer ticks carry Lyme disease, Paskewitz said. About 25 percent of the younger, nymph-stage ticks carry it.

June and July are the prime months for people to watch out for ticks, Paskewitz said. The larger adult ticks are easier to see than the younger nymphs.

People walking in the woods and through high grass should check themselves for ticks, Wesson said. Although there is no set amount of time it takes to contract Lyme disease once a tick is on you, Wesson said the most common threshold is about 24 hours.

A new bacteria found to cause Lyme disease was first discovered in the Midwest in 2013. There have been five cases connected to Borrelia mayonii between 2013 and 2016, according to the division's website.

Wesson said he does not believe they have seen a newer, rarer species in Rock County, but it's “on everyone's radar.”

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