Infection of Rodents by Orientia tsutsugamushi, the Agent of Scrub Typhus in Relation to Land Use in Thailand

The relationship between land use structures and occurrence of scrub typhus agent, Orientia tsutsugamushi infection in small wild mammals was conducted in three provinces of Thailand: Buriram, Loei, and Nan. Orientia tsutsugamushi detection was performed using 16S ribosomal DNA (rDNA) amplicon sequencing approach using Miseq Illumina platform. In total, 387 animals (rodents and shrews) were examined for the bacterium infection. The 16S rDNA sequences of the bacterium were found in nine animals from Bandicota savilei, Berylmys bowersi, Leopoldamys edwardsi, Rattus exulans, R. tanezumi, and Rattus sp. phylogenetic clade 3, yielding 2.3% infection rate, with two new rodent species infected by the bacterium in Thailand: B. bowersi and L. edwardsi. Using a Generalized Linear Mixed Model (GLMM) and Random Forest analyses for investigating the association between human-land use and occurrence of the bacterium, forest habitat appeared as a strong explicative variable of rodent infection, meaning that O. tsutsugamushi-infected animals were more likely found in forest-covered habitats. In terms of public health implementation, our results suggest that heterogenous forested areas including forest-converted agricultural land, reforestation areas, or fallow are potential habitats for O. tsutsugamushi transmission. Further understanding of population dynamics of the vectors and their hosts in these habitats could be beneficial for the prevention of this neglected zoonotic disease