Prevalence and longitudinal dynamics of Mycobacterium avium subsp. paratuberculosis infection in Colombian cattle across different life zones

Abstract Paratuberculosis (PTB) is a chronic infectious disease characterized by granulomatous enterocolitis caused by Mycobacterium avium subsp. paratuberculosis (MAP). This study aimed to evaluate MAP prevalence over time in Colombian cattle using a longitudinal approach with indirect ELISA and qPCR on blood and fecal samples from animals across distinct life zones. A prospective longitudinal study was conducted on 129 cattle from six municipalities, representing different life zones as classified by the Holdridge system through GIS-based extrapolation. Animals were selected by convenience sampling and stratified by age group. Blood and fecal samples were collected three times in 2023. Indirect ELISA was used to detect MAP-specific antibodies, while fecal DNA was extracted and analyzed by qPCR targeting the IS900 gene. Among the 129 cattle sampled, the adjusted apparent prevalence of MAP infection determined by ELISA ranged from 37.2 to 38% across the three time points, with no losses to follow-up. All qPCR results were negative. The adjusted prevalence, accounting for test performance, was 29.9%. Seropositivity increased with age: adjusted prevalence was lowest in calves (< 12 months; 9.3–11.9%) and highest in animals older than 3 years (up to 49%), indicating a consistent age-related trend in MAP exposure. These findings underscore the value of indirect ELISA for longitudinal MAP surveillance and suggest progressive exposure with age. Incorporating ecological context may improve epidemiological interpretations and inform targeted control strategies in endemic areas.