Parasites, Hosts and Diseases

The Korea Society for Parasitology and Tropical Medicine (대한기생충학·열대의학회)
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Prevalence of chigger mites and Orientia tsutsugamushi strains in northern regions of Gangwon-do, Korea

  • Soojin Kim (Department of Biomedical Laboratory Science, College of Software and Digital Healthcare Convergence, Yonsei University) ;
  • In Yong Lee (Department of Tropical Medicine and Institute of Tropical Medicine, Yonsei University College of Medicine) ;
  • Sezim Monoldorova (Department of Biomedical Laboratory Science, College of Software and Digital Healthcare Convergence, Yonsei University) ;
  • Jiro Kim (Department of Biomedical Laboratory Science, College of Software and Digital Healthcare Convergence, Yonsei University) ;
  • Jang Hoon Seo (Department of Biomedical Laboratory Science, Shinhan University) ;
  • Tai-Soon Yong (Department of Tropical Medicine and Institute of Tropical Medicine, Yonsei University College of Medicine) ;
  • Bo Young Jeon (Department of Biomedical Laboratory Science, College of Software and Digital Healthcare Convergence, Yonsei University)
  • Received : 2022.10.26
  • Accepted : 2023.06.22
  • Published : 2023.08.31
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Abstract

The present study aimed to survey the prevalence of chigger mites and Orientia tsutsugamushi (O. tsutsugamushi) infection in the northern regions of Gangwon-do, Korea. From early February to early June 2015, a total of 17,050 chiggers were collected from striped field mice, Apodemus agrarius, in Cheorwon-gun, Hwacheon-gun, Yanggu-gun, and Goseong-gun, which are well-known endemic areas of scrub typhus in Korea. The chiggers were analyzed using molecular genomic methods, as previously described. Among the 7,964 identified chiggers, the predominant species was Leptotrombidium pallidum (76.9%), followed by L. zetum (16.4%), L. orientale (4.3%), L. palpale (0.3%), L. tectum (0.2%), and Neotrombicula tamiyai (1.8%). The chigger index (CI) was highest in Hwacheon (115.58), followed by Cheorwon (97.02), Yanggu (76.88), and Goseong (54.68). Out of the 79 O. tsutsugamushi-positive chigger pools, 67 (84.8%) were identified as the Boryong strain, 10 (12.7%) as the Youngworl strain, and only 2 were the Jecheon strain. Based on the high infestation of chiggers in striped field rodents and the high rate of O. tsutsugamushi infection in chigger mites, Hwacheon-gun and Cheorwon-gun are presumed to be high-risk areas for scrub typhus. Furthermore, L. pallidum, a major vector of scrub typhus, and the dominant O. tsutsugamushi serotype, the Boryong strain, were found in the northern regions of Gangwon-do, Korea.

Keywords

Acknowledgement

We thank Namkyoung Kim and Jonguk Jeong for technical support. This study was supported by a grant from climate change vector surveillance programs of the Korea Disease Control and Prevention Agency (KDCA), and by a grant from Armed Forces Medical Research Institute, The Armed Forces Medical Command, Republic of Korea.

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