Meta-analytical approach reveals context-dependent reduction of zoonotic risk in response to ecosystem restoration

Habitat degradation is accelerating worldwide, altering species assemblages and the ecological interactions that regulate pathogen transmission in wildlife. Because ecosystem restoration can rebuild community structure, improve habitat quality, and potentially reduce contact rates or exposure pathways, it is expected to lower disease risk. Yet the consistence and magnitude of these effects remain unclear, especially when changes in species composition may either amplify or dampen infection dynamics. To address this uncertainty, we synthesized published studies that compared pathogen prevalence across sites classified within a Before-After-Control-Impact (BACI) framework. Our objectives were to determine whether: (I) degraded habitats exhibit higher infection risk than undisturbed controls; (II) restored sites show lower infection probabilities than pre-restoration conditions; and (III) shifts in host community composition accompany these habitat transitions. We compiled 28 independent studies from 48 countries, spanning various habitat types. The dataset included a diverse set of vertebrate hosts and pathogen groups with a notable research bias toward protozoan infections. We evaluated disease outcomes using meta-analytic contrasts, mixed-effects models fitted to individual-level infection data, and multivariate analyses of host-community structure. Global comparisons between undisturbed (control) and degraded (impact) sites showed no consistent direction of change in infection risk across studies, reflecting high ecological and methodological variability. Before-after comparisons suggested a potential decrease in infection following restoration, but the small number of available studies and wide uncertainty prevented firm conclusions. In contrast, the individual-level mixed-effects model revealed a clearer pattern: vertebrates sampled after degradation but prior to restoration consistently showed higher infection probabilities than those sampled after restoration, while control and impact sites did not differ meaningfully from post-restoration conditions. Host-community analyses indicated a small but detectable difference in species composition across BACI stages, although no specific pair of stages showed a strong or consistent shift. Together, these results show that restoration does not generate a universal global reduction in disease risk, yet within local systems, infection probabilities tend to decline following restoration. This suggests that while global patterns remain heterogeneous, targeted restoration actions may yield meaningful disease-mitigation benefits at local scales.