St. Croix County Public Health partnered with the Wisconsin Department of Health Services to complete bi-weekly sampling at selected sites within St. Croix County to capture the seasonal activity of ticks. Tick dragging starts in the spring when temperatures exceed 40°F with no snow cover and continues into the fall. Ixodes scapularis nymphs, also known as deer tick or black-legged tick nymphs, are sent to the CDC for testing for bacteria and parasites associated with tickborne diseases.
Here is an update on the activities and results of the 2024 tick surveillance program. The selected surveillance sites were Willow River State Park and YMCA Camp St. Croix.
- There are at least 16 different tick species found in Wisconsin. In 2024, the CDC targeted the Ixodes scapularis nymph, also known as the deer tick or black-legged tick, for research. The nymphs collected during tick drags were tested for the following tickborne pathogens:
- Borrelia burgdorferi bacteria (causes Lyme disease)
- Anaplasma phagocytophilum bacteria (human and non-human active strains; causes Anaplasmosis in humans and domestic animals)
- Babesia microti parasite (causes Babesiosis)
- Borrelia mayonii bacteria (a strain of Lyme disease)
- Borrelia miyamotoi bacteria (causes Tick-Borne Relapsing Fever)
- Ehrlichman Muris Eauclairensis bacteria (causes Ehrlichiosis)
- Ticks were collected using 1 by 1 meter cloth drags. Drags were pulled along trails, trail edges, and in wooded areas. Drags were a minimum of 750 meters using a measuring tape to maintain consistent dragging distances for calculating acarological risk. All classifications of ticks were collected and put into vials of alcohol and preserved.
- A minimum of 50 Ixodes scapularis nymphs were required for pathogen diagnostics. Nymphs were sent to the DHS Public Entomologist Dr. Xia Lee, who then sent the nymphs to the CDC for testing.
- Listed below are the CDC pathogen testing results:
- Prevalence of the Lyme disease pathogen, Borrelia burgdorferi, in the tested nymphs was between 14-17 %, which is normal for Wisconsin.
- Prevalence of the pathogen that causes babesiosis, Babesia microti, is around 2%, which is normal for Wisconsin.
- Prevalence of the pathogen that causes Anaplasmosis, Anaplasma phagocytophilum human active strain, is around 2% in the nymphs tested from Willow River state park, which is low for Wisconsin. None of the ticks from Camp St. Croix tested positive for Anaplasma phagocytophilum human active strain.
- None of the nymphs tested positive for the other tickborne pathogens.
St. Croix County has successfully met the CDC’s requirement of collecting 50 Black Legged Tick nymphs for testing various tick-borne pathogens. We want to thank partners for their ongoing partnership with the St. Croix County Public Health Department’s Tick Surveillance program.