Nationwide Survey of Vector-Borne Diseases in Rodents and Mites in Korea: Anaplasma, Ehrlichia, and Rickettsia

Rodents are reservoirs for zoonotic pathogens, making it essential to study both rodents and their ectoparasites. In 2022 and 2023, we investigated the spatial distribution of rodents and their mites across Korea, focusing on three vector-borne diseases (VBDs): <i>Anaplasma</i>, <i>Ehrlichia</i>, and <i>Rickettsia</i>. A total of 835 wild rodents were collected from 16 locations, each consisting of five distinct environmental settings (mountains, waterways, reservoirs, fields, and paddy fields), with 20 traps per setting, totaling 100 Sherman live folding traps per site. Each rodent was identified using a taxonomic key, and post-mortem examinations led to the collection of 7971 mites (498 pools), followed by PCR analysis. Among the rodents, <i>Anaplasma phagocytophilum</i> was detected in 10.3%, <i>Ehrlichia muris</i> in 0.5%, <i>Ehrlichia ruminantium</i> in 0.2%, and <i>Rickettsia raoultii</i> in 2.9%. In mites, <i>A. phagocytophilum</i> was found in 8.8%, <i>E. muris</i> in 0.2%, <i>R. raoultii</i> in 0.2%, <i>R. endosymbiont</i> in 1.6%, and <i>R. australis</i> in 1.2%. This study marks the first detection of <i>E. muris</i> and <i>R. raoultii</i> in Korean rodents and the first global discovery of <i>E. ruminantium</i> in rodents. The detection of multiple pathogens in mites worldwide highlights the importance of continuous VBD monitoring to mitigate public health risks.