Statewide Passive Surveillance of and Associated Pathogens in Maine.

The blacklegged tick, , is the primary vector of multiple human pathogens, including the causative agents of Lyme disease, anaplasmosis, and babesiosis. Both and its associated pathogens have expanded their geographic range throughout the northeastern Unites States and into northern New England. Through this study, we present an updated distribution of in Maine and report the first statewide passive surveillance infection and coinfection prevalence of , , and within the state's population. In 2019, we collected 2016 ticks through a passive surveillance program, in which Maine residents submitted tick samples for identification and/or pathogen testing. We used a single multiplex quantitative PCR assay to detect tickborne pathogens in 1901 tick samples. At the state level, we found that and infection rates of adults (42.4%, 11.1%) were nearly double that of nymphs (26.9%, 6.7%), whereas prevalence was similar for both adults (6.5%) and nymphs (5.2%). Spatially, we found an uneven distribution of both tick activity and pathogen prevalence, with both increasing on a north to south gradient. We also noted a potential association between the ratio of adult to nymphal ticks and the incidence of tickborne disease in human populations, with counties that exhibit high rates of human disease also maintaining low adult to nymph ratios.