Seroprevalence of Antibodies Following Tick Bites: A Serosurvey in a Tertiary Care Hospital in Romania.

Human granulocytic anaplasmosis is an emerging tick-borne disease. Although has been identified in vectors and animal reservoirs in Romania, evidence of human exposure has not yet been reported. This study aimed to generate initial evidence of human infection by evaluating antibodies in individuals with recent tick exposure. We conducted a cross-sectional serosurvey between 2023 and 2024 at a tertiary care hospital in Bucharest, enrolling 80 participants 4 to 12 weeks following a tick bite. Serum IgG antibodies against were detected using an indirect immunofluorescence assay, with a titer of ≥1:64 considered indicative of seropositivity. Eight (10%) participants tested positive for IgG antibodies. Seropositivity was not significantly associated with demographics, geographical region, or clinical symptoms. However, fatigue and myalgia were more frequently seen in IgG seropositive individuals. Notably, 43.8% of all participants reported erythema migrans, including five of the eight individuals with positive IgG serology. This study provides the first serological evidence of human exposure to in Romania. A 10% seroprevalence in this high-risk group suggests that anaplasmosis may be underrecognized. Clinicians should consider it in patients with tick exposure and compatible symptoms.