Prevalence of in Ticks, Minnesota, 2017.

The prevalence of in Minnesota ticks is unknown. Ticks collected at seven sites were tested to determine the infection prevalence of in in Minnesota. Ticks were collected from two properties at an epizootic site and at five long-term tick research sites. Ticks were pooled by species, sex, date, and site with a maximum of 10 ticks per pool. Ticks were bisected and homogenized; DNA from supernatant was extracted and tested by real-time PCR (RT-PCR). Twice, additional ticks were collected for bacterial culture and isolation of . Proportion of positive pools and minimum infection rate (MIR) were calculated. A total of 3527 ticks were tested for including 1601 male and 1926 female . Across all sites, 128 (34%) of 378 pools were RT-PCR positive for . Of 128 positive pools, from 96 (75%) was identified as type A; from 32 pools was unable to be subtyped. The overall MIR was 3.6%. The MIR was significantly lower at the epizootic site compared with Morrison County 1 (3.9% vs. 7.2%;  = 0.02) but did not differ between the epizootic site and Pine County 1 (3.9% vs. 2.1%;  = 0.49). Within the epizootic site, the MIR was significantly higher at Washington County 2 compared with the adjacent property (5.7% vs. 2.3%;  < 0.001). was cultured from 6 (15%) of 40 pools. was found in ticks at a majority of sites tested. The MIR of in ticks in Minnesota varied geographically. Our findings support the hypothesis that plays an important role in the natural history of tularemia in Minnesota. Further ecologic studies are needed to fully understand the importance of tick species in the maintenance and transmission of in Minnesota.