Age-related Mycobacterium avium subsp. paratuberculosis seroprevalence in Colombian cattle across 6 ecologic life zones.

Mycobacterium avium subsp. paratuberculosis (MAP) prevalence estimates vary widely across Colombian regions, with no prior longitudinal assessment of Colombian dairy systems across ecologic life zones. We assessed the temporal dynamics of MAP infection in Colombian cattle across 6 distinct ecologic life zones and explored age-related differences in MAP detection using combined serologic and molecular approaches. We longitudinally sampled 129 cattle from 6 municipalities in distinct Holdridge life zones. The animals were stratified by age group and sampled 3 times at 2-mo intervals during 2023 (Aug-Dec). Serum and fecal samples were tested by indirect ELISA and IS900 real-time PCR (rtPCR), respectively. The apparent ELISA prevalence remained stable between 37.2% and 38% across sampling rounds (adjusted true prevalence = 29.9%). Seropositivity increased consistently with age, from 11.9% in animals <1-mo-old to 49% in animals ≥3-y-old. All of the fecal samples tested negative by rtPCR. No consistent seroprevalence clustering was observed across ecologic life zones on descriptive assessment, although management and host factors were not evaluated. We found longitudinal evidence of stable, age-related MAP seroprevalence across ecologic zones in Colombia, highlighting subclinical persistence and diagnostic limitations.