Prevalence and Coinfection of Three Tick-Borne Pathogens in Questing Adult Blacklegged Ticks (Vilas County, Wisconsin).

In North America, the blacklegged tick () is a vector of several human pathogens, and tick-borne disease incidence is increasing. We estimated the prevalence of questing blacklegged ticks vectoring three zoonotic pathogens in Vilas County, Wisconsin. We collected 461 adult blacklegged ticks and used PCR to screen for the presence of pathogens that cause Lyme disease (), human granulocytic anaplasmosis (HGA, ), and babesiosis (). We found that 52.5% of ticks carried at least one pathogen. The estimated infection prevalence in the tick population was 17.4% (Lyme disease), 14.3% (HGA), and 6.5% (babesiosis). Multiple pathogens were present in 14.3% of ticks surveyed. About half of questing ticks tested in this study carried at least one zoonotic pathogen. Coinfection was common in our study area and, if not properly recognized, leads to greater risk of underdiagnosis.