Lyme Disease Tick Infection Maps
These maps show the percentage of adult and nymph Ixodes scapularis ticks (black-legged ticks) collected during 2017–2021 that were infected with Borrelia burgdorferi, the causative agent of Lyme disease. The ticks were collected in the field by the Indiana State Department of Health (ISDH) and tested at the Centers for Disease Control and Prevention (CDC). This map will be updated as ISDH continues to conduct surveillance for B. burgdorferi in ticks.
Counties colored darker blue had higher percentages of infected ticks, while counties colored lighter blue had lower percentages of infected ticks. Counties colored white had ticks collected, but none were positive. Counties colored dark grey had sampling conducted, but no Ixodes scapularis ticks were found.
Each county is labeled with the number of ticks that were tested. The reported percentages from counties with small numbers of ticks tested (fewer than 50) should be interpreted with caution. For example, a county with only one tick tested would be colored darker blue if that tick were positive for B. burgdorferi, but this is not enough data to draw conclusions about the entire county.
These data are intended to provide members of the public and health care providers with information on where ticks infected with B. burgdorferi have been detected in Indiana. However, it is important to remember that black-legged ticks have been found in most Indiana counties. In addition, other tick-borne diseases such as ehrlichiosis and the spotted fever group rickettsioses are present in Indiana, but are not shown on this map. Hoosiers should take precautions against tick bites when spending time outdoors in all parts of the state.
For interactive versions of these maps, click here.
For maps and statistics describing human cases of Lyme disease in Indiana, click here.
Figure 1: Percentage of adult Ixodes scapularis ticks infected with Borrelia burgdorferi, 2017-2021.
Figure 2: Percentage of nymph Ixodes scapularis ticks infected with Borrelia burgdorferi, 2017-2021.
Page Last Updated: January 5, 2022