Number of Lyme disease cases in Minnesota by year
Although case counts vary from year to year, the overall trend for Lyme disease in Minnesota is an increase in cases. The highest number of cases were reported in 2013, with 1,431 confirmed cases. In 2017, Minnesota had a rate of 25.2 cases per 100,000 people compared to the national rate of 9.1 cases per 100,000 people.
Many factors may explain this increase, including increasing awareness by doctors, increasing infection rates in ticks, and expanding tick distribution.
Distribution of Lyme disease cases in Minnesota over time
Lyme disease is becoming even more common in Minnesota. There are more cases reported and the cases are being found in more counties. Since 1996, Lyme disease seems to be expanding to the north and west of the traditional risk areas in north central Minnesota.
Number of cases of Lyme disease in Minnesota by month of illness onset, 2000-2017
Blacklegged ticks (also called deer ticks) are active and feeding in late May through June, with a smaller peak in the fall. Signs and symptoms of Lyme disease appear between 3 and 30 days after a bite from an infected tick, so most people who develop Lyme disease in Minnesota first experience symptoms in the summer.
Number of cases of Lyme disease in Minnesota by age and sex, 2000-2017
There are more reports of Lyme disease in males than females for all age groups, except those over age 85. Most reports of Lyme disease cases are in males age 10 to 14 years. There are likely more reports in males and children due to their greater levels of outdoor activity.
Despite the differences in the number of cases between males and females, the overall trend is the same for both sexes: there is a peak in children age 5 to 14 and another peak in adulthood. This secondary peak in cases comes from age 45 to 54 in men and from age 55 to 59 for women.
Symptom presentation of Lyme disease patients in Minnesota, 2000-2017
Most people with Lyme disease have erythema migrans - the "bull's eye rash." Other possible manifestations of Lyme disease include arthritis, neurological issues, heart issues,and brain inflammation, but these are less common. Occasionally, people experience more than one manifestation of Lyme disease.
Forested areas present a risk for tick-borne disease
In order to have a significant risk of getting Lyme disease - and other tick-borne diseases, somebody must be in areas where ticks live. For more information about the risk of tick-borne diseases, see this Tick-Borne Disease Risk Map.