Abstract
Scrub typhus, caused by Orientia tsutsugamushi and transmitted by chigger mites (Leptotrombidium), is a major health problem in northern Thailand, particularly in Nan province. This study investigated the impact of land cover changes on scrub typhus transmission in Nan Province between 2003 and 2019. Using the open land cover data of the European Spatial Agency Climate Change Initiative (ESA CCI), we quantified land cover composition and changes and integrated public health data on scrub typhus cases, as well as information on elevation, population, and slope. Generalized Additive Models were applied to assess the effects of land cover changes on annual scrub typhus cases. Cases increased with shrubland and mosaic land, displayed an inverted U-shaped relationship with broadleaf forest, and decreased with needleleaf forest. Key land cover change factors included shrubland transitions, stable rainfed cropland, cropland to urban shifts. Reforestation (from shrubland to broadleaf forest) showed an inverted U-shaped relationship with cases, while loss of shrubland to grassland and loss of cropland to urban decreased the number of scrub typhus cases. This study highlights the importance of land cover changes in understanding disease transmission and suggests that landscapes disturbance may create optimal conditions for O. tsutsugamushi transmission.