Lyme Disease: Wisconsin Data

Lyme disease is native to Wisconsin. There has been an increase in disease incidence over the last three decades as Lyme disease has spread across the state.

In 2020, Wisconsin had 3,076 estimated cases of Lyme disease. The average number of reported cases has more than doubled over the past 15 years.

The Centers for Disease Control and Prevention (CDC) estimates the total number of cases of Lyme disease in the U.S. is more than 10 times higher than what is reported through surveillance. The total number of cases occurring each year in Wisconsin is likely much greater than what is reported. Wisconsin is one of the states reporting the highest number of cases.

Below are the statewide data for Lyme disease. For information on national Lyme disease data, visit the CDC National Lyme Disease Data and Statistics page.Lyme disease map

Visit the easy-to-use Wisconsin Environmental Public Health Tracking data portal for information on county-level data.

Borrelia burgdorferi Data

Lyme Disease Cases in Wisconsin (1990–2020)

This graph shows Wisconsin Lyme disease cases broken down by confirmed, probable, and estimated cases.

Total Lyme disease cases 1990-2020
In 2008, the surveillance case definition changed to include probable cases. In 2012, the Division of Public Health modified the way in which Lyme disease surveillance is conducted to address the increased burden of Lyme disease reporting on local health departments and medical care providers. This change introduced the need for estimated cases to account for those cases that would have been reported through the surveillance system prior to 2012.

Lyme Disease Incidence in Wisconsin (1990–2020)

This incidence trend line of Lyme disease cases reflects what is shown in the bar graph above.

Lyme disease incidence graph 1990-2000

Cases Reported by Month and Age

Month of Illness Onset

Most cases of Lyme disease occur in the months of June and July. However, it is possible to get Lyme disease whenever ticks are active (when temperatures are above freezing). It is important to always use prevention techniques when spending time outdoors.

Lyme disease cases by month 2016-2020

Age Group

Lyme disease is seen most frequently in younger and older Wisconsinites. However, people of all ages can become infected with Lyme disease.

Lyme disease by age group 1990-2020

Borrelia mayonii Data

Most cases of Lyme disease are caused by the bacterium B. burgdorferi. However, a rare, newly emerging species, B. mayonii, was first detected in 2013 in the Midwest, with nine cases in Wisconsin residents from 2013 to 2020.

Lyme Disease Cases in Wisconsin (2013–2020)

B. mayoni, Lyme disease cases in Wisconsin

Cases Reported by Month and Age

Month of Illness Onset

B. mayonii, Lyme disease cases by month

Age Group

B. mayonii, Lyme disease cases by age group

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Last Revised: June 15, 2022