Molecular investigation of tick-borne pathogens in ticks from grazing cattle in Korea

• H. longicornis is the most common tick species infest grazing cattle in Korea.
• The first time a large number of tick-borne pathogens was investigated in Korea.
• Out of fifteen tick-borne pathogens, ten was detected in five provinces.
• Ehrlichia muris infection was the first time reported in Korea.
• Eight tick-borne pathogens were the first time reported in four provinces of Korea.

This study was carried out to identify the tick species that infest grazing cattle and to determine the presence of tick-borne pathogens transmitted by these ticks in Korea. A total of 903 ticks (categorized into 566 tick pools) were collected from five provinces during 2010–2011. The most prevalent tick species was Haemaphysalis longicornis, followed by three Ixodes spp. ticks. The collected ticks were infected with both rickettsial and protozoan pathogens. In all, 469 (82.9%) tick pools tested positive for the Anaplasma/Ehrlichia 16S rRNA gene, whereas 67 (11.8%) were positive for the Babesia/Theileria 18S rRNA gene. Among the rickettsial pathogens, E. canis was detected with the highest rate (22.3%), followed by A. platys (20%), E. chaffeensis (19.4%), E. ewingii (19.3%), Rickettsia sp. (12.4%), A. phagocytophilum (5.5%) and E. muris (0.5%). Among the protozoan pathogens, T. equi was detected with the highest rate (7.2%), followed by T. sergenti/T. buffeli (3.7%) and B. caballi (0.35%). Simultaneous infections with up to seven pathogens were also identified. In particular, ticks infected with rickettsial pathogens were also infected with protozoan pathogens (22 samples). All five provinces investigated infected with tick-borne pathogens.

Map of Republic of Korea indicating the five provinces where specimens were collected (marked as solid square). The Korean provinces are as follows: Gyeonggi (GG); Gangwon (GW); Chungnam (CN); Chungbuk (CB); Jeonbuk (JB); Gyeongbuk (GB); Jeonnam (JN); Gyeongnam (GN); Jeju (J).Figure optionsDownload as PowerPoint slide