Epidemiology and risk factors of Lyme disease in Taiwan from 2007 to 2020

Background: Lyme disease or Lyme borreliosis is the most commonly transmitted tick-borne infection in the United States and among the most frequently diagnosed tick-borne infections worldwide. Lyme disease is caused by Borrelia burgdorferi. Aim: In this study, we explored the epidemiological characteristics, differences, and trends in domestic and imported cases of Lyme disease in Taiwan between 2007 and 2020 according to patient sex, age, month of confirmation, and area of residence. Methods: We analyzed publicly available annual summary data on domestic cases of Lyme disease from 2007 to 2020 obtained from a Taiwanese Centers for Disease Control (TCDC) database. In total, 17 confirmed imported cases of Lyme disease were reported. Results: Cases in individuals aged 20–59 years gradually increased, and a distinct pattern of seasonal variation (summer) was observed as a potential risk factor. Furthermore, more men had domestically acquired Lyme disease, and cases were identified in individuals living in the Taipei metropolitan area (11 cases [64.7%]) and rural areas (Gao-Ping region, three cases [17.6%]). Imported cases originated in North America (11 cases [64.7%]) and Europe (6 cases [35.3%]). The incidence of Lyme disease per million population was 0–0.13. The incidence of Lyme disease increased from 2007–2013 to 2014–2020, indicating that the recentness of imported cases may be a risk factor. Conclusion: This is the first study to compare imported cases of Lyme disease from 2007 to 2020 from the surveillance data of the TCDC database. This study highlights the essentiality of longitudinal and geographically extended studies in understanding zoonotic disease transmission in Taiwan. Our findings may inform future surveillance and research efforts.