Tick-borne bacterial pathogens in wildlife and their parasitizing ticks in Korea: A molecular epidemiological study

Ticks are important vectors of numerous zoonotic pathogens, yet integrated molecular surveillance of wildlife hosts and their parasitizing ticks remains limited in Korea. In this study, we investigated the occurrence of major tick-borne bacterial pathogens in wildlife and their associated ticks. Blood samples were collected from Korean water deer (Hydropotes inermis), raccoon dogs (Nyctereutes procyonoides), and wild boars (Sus scrofa), and a total of 246 ticks were obtained from these 34 animals. Molecular analyses identified multiple bacterial pathogens, including Anaplasma phagocytophilum, Ehrlichia canis, Bartonella schoenbuchensis, Rickettsia raoultii, Rickettsia monacensis, and Candidatus Rickettsia longicornii. Notably, E. canis was detected for the first time in blood samples from raccoon dogs and wild boars in Korea, and B. schoenbuchensis was identified in ticks for the first time in the country. In addition, R. monacensis exhibited a remarkably high minimum infection rate in Ixodes nipponensis, and all positive ticks were collected from raccoon dogs. Strikingly, Ca. R. longicornii was detected at a very high prevalence (94.1%) in wildlife blood samples, suggesting extensive circulation among wildlife hosts in the study area. These findings indicate that wildlife and their parasitic ticks may serve as important reservoirs of diverse tick-borne bacteria in Korea and highlight the importance of continuous molecular surveillance within a One Health framework.