Detection and Genotypic Analysis of Anaplasma bovis and A. phagocytophilum in Horse Blood and Lung Tissue

A clinical case of was reported for the first time in our previous study (2019) in a horse, a nondefinitive host. Although is a ruminant and not a zoonotic pathogen, it is responsible for persistent infections in horses. In this follow-up study, the prevalence of spp., including , was assessed in horse blood and lung tissue samples to fully understand spp. pathogen distribution and the potential risk factors of infection. Among 1696 samples, including 1433 blood samples from farms nationwide and 263 lung tissue samples from horse abattoirs on Jeju Island, a total of 29 samples (1.7%) tested positive for and 31 (1.8%) samples tested positive for , as determined by 16S rRNA nucleotide sequencing and restriction fragment length polymorphism. This study is the first to detect infection in horse lung tissue samples. Further studies are needed to clarify the comparison of sample types within cohorts. Although the clinical significance of infection was not evaluated in this study, our results emphasize the need to clarify the host tropism and genetic divergence of to enable the development of effective prevention and control measures through broad epidemiological studies.