Fengmiao Zhao, Luyao Hao, Emilia Lopez Seco, Sagara Kumara, Guodong Han, Pablo Gregorini
Mycobacterium avium subsp. paratuberculosis (MAP), the causative agent of paratuberculosis or Johne's disease, causes substantial economic losses in domestic ruminants. However, the global epidemiological burden of MAP infection in cervids remains insufficiently characterized. This systematic review and meta-analysis aimed to estimate the global prevalence of MAP infection in deer and to explore potential geographic, host-related, management-related, and methodological sources of heterogeneity. Six electronic databases were systematically searched for eligible epidemiological studies published up to April 2026. Pooled prevalence estimates were calculated using a random-effects model, and heterogeneity was assessed through subgroup analyses and meta-regression. Fifty studies involving 83,674 deer were included. The overall pooled prevalence of MAP infection was 10.6% (95% CI: 6.6%-15.4%), with substantial between-study heterogeneity (I² = 98.5%). Living status was strongly associated with apparent prevalence, with farmed deer showing the highest estimate (18.17%), followed by captive/mixed populations (9.26%) and wild deer (5.01%). Host-related variation was also evident, with higher pooled prevalence observed in sika deer (17.81%), white-tailed deer (13.40%), and red deer (13.17%) than in roe deer and elk. Serum-based studies yielded a higher pooled prevalence (10.96%) than fecal-based studies (4.07%), suggesting that diagnostic approach may substantially influence prevalence estimation. Temporal meta-regression showed no significant linear change in MAP prevalence over time (p = 0.5658). These findings indicate that MAP infection is globally distributed in deer populations, particularly among farmed sika and red deer. Strengthened diagnostic standardization, farm biosecurity, young-deer management, and integrated surveillance across farmed deer systems and the deer-wildlife-environment interface are needed to support risk-based control of cervid paratuberculosis within a disease ecology framework.