Modelling transmission and control of Mycobacterium avium subspecies paratuberculosis within Irish dairy herds with compact spring calving

Paratuberculosis is a chronic bacterial infection of the intestine in cattle caused by Mycobacterium avium subspecies paratuberculosis (Map). To better understand Map transmission Irish dairy herds, we adapted French stochastic individual-based epidemiological simulation model to account for seasonal herd demographics. We investigated probability persistence over time, within-herd prevalence and relative importance pathways, assessed effectiveness test-and-cull control strategies. impact on outputs calf separation from cows (calves grazed pasture adjacent vs. were completely separated cows) test-and-cull. Test-and-cull scenarios consisted highly test-positive culled within 13 or 4 weeks after detection, born kept vs removed. simulated typical with average 82 lactating cows, 112 animals total. Each scenario was iterated 1000 times adjust variation stochasticity. introduced fully naive through purchase moderately infectious primiparous cow. Infection considered persist when at least one infected animal remained present environment. The 15 years introduction ranged between 32.2–42.7 % calves had contact pasture, 18.9–29.4 pasture. most effective strategy cull four detection (absolute 10 lower compared without control). Removing offspring dams did not affect either Map. Mean highest (63.5 %) decrease) high result, 28 weeks. Around calving, rate high, being utero via general indoor environment (most important routes). For remainder year, incidence relatively low cows. Testing culling an it used prior calving period minimize number born.