Epidemiology and clinical features of patients with tick bites in the Japanese spotted fever-endemic zone.

Abstract

Purpose: This study aimed to clarify the epidemiology and clinical features of tick bites in a Japanese spotted fever (JSF)-endemic area.

Method: The clinical records of patients with tick bites were retrospectively reviewed based on a survey conducted at Numakuma Hospital, Fukuyama City, Hiroshima, Japan, from 2016 to 2023. Data on basic characteristics, visit dates, residential address, exposure activities, tick-bite sites, and prophylactic antimicrobial prescriptions for each patient with tick bites were collected at the JSF hotspot hospital.

Results: A total of 443 patients with tick bites visited the hospital, of which data on 305 cases (68.8 %) were reviewed. The median age of these patients was 71 years, with a higher proportion of women (63.0 %). One-third of the patients had a preceding history of working in fields, whereas two-thirds had entered mountains or agricultural fields. Nearly 90 % of the patients visited the hospital from April to August, and the most common bite sites were the lower extremities (45.1 %). Most patients (76.1 %) resided in the southern area of Numakuma Hospital. Nearly all patients were prescribed prophylactic antibiotics (minocycline in 87.8 % of cases), and none subsequently developed JSF.

Conclusion: Continued surveillance of patients with tick bites is warranted to better understand changes in the clinical impact of tick-borne diseases.