ABSTRACT: A phylogenetic analysis of Orientia tsutsugamushi was performed to elucidate its antigenic diversity in chiggers, small mammals, and patients. Between September 2014 and December 2016, a total of 3,816 chiggers were identified within nine species of four genera in the southwest region of Korea: Leptotrombidium scutellare (49.9%; 1,907/3,816), Leptotrombidium orientale (21.1%; 804/3,816), Leptotrombidium pallidum (12.4%; 474/3,816), Euchoengastia koreaensis (7.2%; 273/3,816), Leptotrombidium palpale (6.7%; 256/3,816), Neotrombicular gardellai (1.3%; 50/3,816), Leptotrombidium zetum (0.8%; 32/3,816), Walchia fragilis (0.5%; 18/3,816), and Neotrombicular japonica (> 0.1%; 2/3,816). Twelve chiggers (11 L. scutellare a
