Summer is prime tick season in Wisconsin, and we have more cases of Lyme disease than any other state in the country.

It's caused by a bite from a deer tick. And usually, a bulls eye rash is the result. But some people have no symptoms and end up undiagnosed, untreated, and in pain.

For years, the Egler family battled the elusive attacker.

Lauren Egler explained her frustration and pain. "I've been diagnosed with fibromyalgia, chronic fatigue, adrenal fatigue, Epstein Barr virus."

Matt Egler suffers too. "Vertigo, like anytime I stand up, I kind of get color that blurs my vision."

Adam Egler said this. "Every day, I'm just kind of tired pretty much all the time."

Ashley Egler had a similar story to share. "Sometimes light sensitivity, sound sensitivity."

The Eglers believe they have chronic Lyme disease. Doctors don't agree.

But Nancy McKay knows just how they feel. She has suffered 20 years of pain and flu-like symptoms.

"I went to neurologists, rheumatologists, MD's, and not one of them, not one, thought of it," she said.

There are so many stories, filmmakers actually chronicled them in a documentary.

So do they have Lyme disease? When doctors performed the standard blood test for Lyme, it came back negative. Patients said they're then dismissed and left untreated. They believe the test is simply inaccurate.

"That's what's so crazy," Lauren Egler told us. "That if doctors start looking for this right away, people wouldn't get as sick."

Usually, the telltale sign of Lyme disease is a bulls eye shaped rash. A simple course of antibiotics cures it.

If there's no rash, it can take months to diagnose.

Nancy McKay says that's what happened to her... And only IV antibiotics helped her.

"I'm much better. See my hands? I was like this.. my whole body was doing that. I was shaking everywhere," she demonstrated.

Mainstream medicine doesn't exactly buy "chronic Lyme disease" as a diagnosis-- but do say Lyme disease can leave some long-term health problems.

Your best bet-- avoid ticks altogether. Terry Jensen, who is with the Wisconsin DNR, said there are things you can do to protect yourself. "You should wear light colored clothing and try to seal off the arms and legs with duct tape or something like that."

When you get home, check to make sure you haven't picked up any ticks.

The typical Lyme disease rash can show up within three days... Or take as long as a month to manifest.

Last year Wisconsin had nearly 1,500 cases of Lyme disease. That's an increase over 2007.