University of Wisconsin–Madison

Infection rates: blacklegged (deer) tick nymphs with Borrelia burgdorferi

Nymph rates by countyFigure 1.  This is a summary of recent work on infection rates from questing nymphs collected from multiple locations in Wisconsin.  The first number is the number of deer tick nymphs that were positive for Borrelia burgdorferi (causative agent for Lyme Disease).  The second number is the total number of nymphs that were tested.  So in Iowa County 8 of 58 nymphs (14%) were positive in this sample.  Finally, we observe quite a bit of variation between years in these infection rates.  For example, in the Black River State Forest we observed nymphal infection rates of 20, 35 and 11% in 2009, 2010, and 2011.  In 2012, there were too few nymphs to test due to drought.  We can’t yet predict whether infection rates will be lower or higher in a given year.