Epidemiological characteristics of cases with scrub typhus and their correlation with chigger mite occurrence (2019-2021): A focus on case occupation and activity locations

Scrub typhus, transmitted through chigger mite bites, is a febrile disease associated with agricultural activities and primarily occurs in autumn. To address the increasing number of cases with scrub typhus over the past 3 years, we analyzed activity, visit history, and occupation data of 12,462 cases reported to the Korea Disease Control and Prevention Agency (KDCA) between January 2019 and December 2021. We examined changes in incidence and general characteristics by visualizing the incidence and eschar bite locations using population data and a geographic information system. Gyeongsangnam-do had the highest overall incidence rate (22.7%), followed by Jeollanam-do (19.0%) and Jeollabuk-do (11.2%), during the study period. However, when considering the incidence rate per 100,000 people, Jeollanam-do had the highest number of cases at 129.1, followed by Gyeongsangnam-do (85.1 cases) and Jeollabuk-do (78.1 cases). Most cases were women (61.0%) in their 70s (28.4%), and the highest incidence occurred in the agricultural worker group during autumn (October-December). Bites occurred most frequently in the abdomen (18.1%), and fever (79.2%) and muscle pain (49.8%) were the main symptoms. We also found a positive correlation (r = 0.848) between chigger mite populations and disease outbreaks over 3 years. In conclusion, it is crucial to provide education on identifying the habitats of chigger mites and rodents (vectors), as well as the appropriate application of repellents. Promoting awareness and preventive measures against infectious diseases is of utmost importance for rural areas and the general public who frequently come into contact with natural environments.