May 31, 2018

Tick season in Wisconsin

The warm weather can only mean one thing: It’s tick season. And in this case, the season lasts from spring through fall, with the peak occurring in the summer months of June, July and August.

Unfortunately, the little critters are more than just an annoyance; they’re a potential source of illness. Dr. Greg Gauthier, UW Health infectious disease specialist, said that in Wisconsin the most common tick to transmit infection is the deer tick (Ixodes scapularis).

While there are 15 tick-borne illnesses in the U.S., the following tick-borne diseases affect Wisconsin and the upper Midwest:

  • Lyme disease (Borrelia burgdorferi, Borrelia mayonii)

  • Anaplasmosis (Anaplasma phagocytophilum)

  • Babesiosis (Babesia microti)

  • Ehrlichiosis (Ehrlichia chaffeensis, Ehrlichia muris-like agent)

  • Powassan virus/Deer tick virus

The “big three” in Wisconsin are lyme, anaplasmosis and babesiosis with Lyme being the most prevalent followed by anaplasmosis and babesiosis. Ehrlichiosis is uncommon in Wisconsin; however, in 2011, a new agent of ehrlichiosis, called ehrlichiosis-muris like agent (EMLA) was reported in Wisconsin. Rocky Mountain Spotted Fever is rare in Wisconsin, with most people becoming infected in another state prior to their return to Wisconsin.

Dr. Gauthier cautions that just because you find a tick on you, that does not necessarily mean you’ll acquire one of the illnesses.

“Ticks must be attached for a certain number of hours to transmit disease,” he said. For transmission of Lyme disease, the tick would need to be attached for at least 3648 hours. Anaplasmosis can be transmitted in less than 48 hours.

Some individuals may have heard a new type of Lyme disease was found earlier this year in Wisconsin and Minnesota — Borrelia mayonii. Previously, it was thought only one type of bacteria caused Lyme — Borrelia burgdorferi. But researchers identified a new species in six individuals whom were tested for Lyme disease. While it’s believed that current treatments for Lyme disease will work for Borrelia mayonii, Gauthier said that, “there have been so few cases described, more understanding of its clinical presentation is still needed.”

Symptoms of illness

The symptoms of the different tick-borne illnesses are not always easy to diagnose. Nearly all tick-borne infections include possible flu-like symptoms, but Dr. Gauthier notes other symptoms include:

  • Lyme: There are three phases of Lyme if it is left untreated. The most common clinical finding is a bull’s-eye rash that often occurs at the site of the tick bite. Other symptoms can include joint pain, muscle aches, severe headache, heart palpitations and joint swelling.

  • Anaplasmosis and ehrlichiosis: Both of these illnesses present in similar ways. “Lab testing is necessary to determine whether the illness is from Anaplasmosis or Ehrlichiosis,” he said, adding that common symptoms include flu-like illness, fever, chills, muscle aches and sometimes GI symptoms. Rashes are not common. Laboratory testing can demonstrate a low white blood cell count, low platelet count and elevation of certain liver enzymes.

  • Babesiosis: As with the others, Babesiosis includes fever, chills and fatigue. Because Babesia microti infects red blood cells, it causes hemolytic anemia, which can be detected via a blood test.


Laboratory tests are available to help diagnose tick-borne infections


The tips to prevent tick-borne illnesses are all ones you’ve heard before. The most obvious being to avoid wooded areas and tall grass. But since many Wisconsin residents love being outdoors, there are other precautions that can help:

  • Wear repellant that contains 20-30 percent DEET (side benefit — this helps with mosquitoes, too)

  • Clothing with permethrin can be helpful

  • Inspect yourself after spending time outside and ask someone to check the spots you can’t see — look in armpits, behind knees, at the waistline, in ears, hair — generally all over

  • Check pets for ticks. You can’t get sick from your pet, but the ticks might decide to change hosts and pick you instead.

  • Take a shower as soon as possible.

It can take time for a tick to embed, so a shower can help knock off any that might not be attached. And if one does become attached, use tweezers to hold the tick close to its head and pull upward with steady pressure. Don’t twist or jerk as the might cause the tick’s mouthparts to remain in the skin.