Seroprevalence and molecular detection of Lawsonia intracellularis from asymptomatic horses in Korea

The study was performed to investigate the prevalence pattern of Lawsonia intracellularis in horses in Korea via serology and molecular detection. Total of 138 horse sera and 112 fecal samples, in pairs with sera, were collected from five provinces across the country. The sera were analyzed using blocking enzyme-linked immunosorbent assay (bELISA) to detect L. intracellularis-specific antibodies and the fecal samples were evaluated by the real-time PCR assay to detect DNA of L. intracellularis. Results showed that 94% of the horses had antibodies and the younger the age, the higher the seropositivity; " < 2 years" (92%), "2-5 years" (96%), "6-10 years" (94%), and " > 10 years" (93%). DNA of L. intracellularis was identified in 18% of the horses and neither sex- nor breed-dependent difference was observed. Rather, like serology, the younger the age, the higher the positivity; " < 2 years" (43%), "2-5 years" (25%), "6-10 years" (13%), " > 10 years" (8%). The results indicated that the agent was prevalent across various age groups and once infected at a young age, it could persist for a long time in the groups, spreading via fecal-oral route. Although the research was conducted on clinically healthy horses, a considerable portion of horses were found to be subclinically infected. Therefore, clinicians as well as horse industry workers should be alert to the pathogen as another must-have test to establish diagnostic criteria for equine enteric diseases.