Surveillance of Chigger Mite Populations in the Republic of Korea in 2024.

Objectives: Chigger mites are the primary vectors of scrub typhus in the Republic of Korea (ROK), with their larval activity peaking in autumn. Their occurrence is influenced by climatic factors and closely associated with human cases, highlighting the need for ongoing surveillance and analysis. This study examined the distribution of chigger mites to provide baseline data for vector monitoring, prevention, and control. Methods: Surveillance was conducted for 16 weeks (August 29-December 18, 2024) at 18 sites nationwide using mite traps. Four environments (grassland, waterway, rice paddy, and field) were surveyed using five traps each (20 traps per site). Their density was measured as the mean number of individuals per trap (trap index) for comparison. Results: In total, 3,114 mites (15 species and 5 genera) were collected. Conclusions: The activity of chigger mite larvae was most vigorous within a specific temperature range. As a result, their emergence tended to occur later at lower latitudes. These findings suggest that the survival, growth, and activity of chigger mite larvae are closely associated with climatic factors. Furthermore, the number of scrub typhus cases increased approximately 1-3 weeks after the increase in larval density, which is consistent with the incubation period of the disease. These findings highlight the fact that ongoing climate change in ROK may increase vector populations and the risk of vector-borne diseases, emphasizing the importance of preventive measures and continuous surveillance.