Predicting the global potential distribution of tow major vectors of scrub typhus under future climate scenarios

Background. Scrub typhus is a mite-borne disease caused by Orientia tsutsugamushi (Ot), primarily transmitted by the chigger mites Leptotrombidium deliense (L. deliense) and Leptotrombidium scutellare (L. scutellare). To effectively control the transmission of this disease, it is essential to clarify the spatial distribution of suitable habitats for its vector species. This research focuses on estimating the global potential distribution of Leptotrombidium deliense and Leptotrombidium scutellare under both current and projected future climate conditions. Additionally, the study aims to evaluate the influence of key climatic variables on the geographical patterns of these two vectors. Methods. Data on species distribution were obtained from the Global Biodiversity Information Facility (GBIF) and from publicly published literature in databases such as Web of Science and PubMed. The environmental variables were downloaded from WorldClim Global Climate Database. The Maximum Entropy Model was used to evaluate the contribution of elevation, slope, aspect and nineteen bioclimatic variables to vector survival, as well as to predict the suitable area for the vectors. Results. It indicated that L. deliense predominantly occurs in southern China, India, Australia, and Southeast Asian regions. In contrast, L. scutellare is largely restricted to southern and eastern coastal areas of China. L. deliense displays greater adaptability to tropical zones, whereas L. scutellare shows higher survival potential in temperate zones. Specifically, L. deliense demonstrates significant sensitivity to precipitation during both the warmest and wettest quarters, indicating a ecological preference for hot and humid tropical environments, while L. scutellare is more sensitive to precipitation of warmest quarter. Under the SSP5-8.5 scenario, the suitable habitat areas for the two species are expected to increase by 84.58% and 148.50%, respectively, compared to historical levels. Climate change will have a significant impact on the expansion of suitable habitats for these species. Conclusions. To effectively prevent disease outbreaks and their spread, it is recommended to further strengthen disease surveillance and control measures in highly suitable areas where vector organisms are already present. Simultaneously, entry-exit quarantine and vector invasion monitoring capabilities should be enhanced in other highly suitable regions to prevent the introduction and establishment of foreign vector species.