Global epidemiological landscape and diagnostic biases reveal persistent endemic circulation of porcine epidemic diarrhoea virus: a systematic review and meta-analysis

Porcine epidemic diarrhoea virus (PEDV) is a major enteric pathogen of global swine production, yet its true epidemiological burden remains inadequately characterised due to heterogeneity in surveillance systems, diagnostic sensitivity, and reporting frameworks. To clarify the global epidemiological profile of PEDV, we conducted a systematic review and meta-analysis integrating animal- and herd-level data while evaluating the influence of diagnostic methods and population characteristics on detection outcomes. Across 133 studies from 22 countries, PEDV was frequently detected in both clinically affected and apparently healthy pigs, indicating sustained endemic circulation rather than episodic outbreak dynamics. Molecular assays identified ongoing active infection, while serological data demonstrated extensive historical exposure, together revealing substantial silent transmission within swine herds. Detection patterns varied markedly by age group, geographic region, and study period; sows appeared to act as potential viral reservoirs, while neonatal piglets served as principal transmission amplifiers. Among clinically affected pigs, pooled nucleic acid-based detection rate was 46.0% (95% CI: 39.8-52.2), with the highest point estimates observed in sows and boars at 76.5% (95% CI: 28.9-100.0), though these were imprecise with wide confidence intervals, and in suckling piglets at 44.7% (95% CI: 35.6-53.9). Serological analysis revealed a seroprevalence of 14.6% (95% CI: 0.8-40.0) in clinically affected animals, reflecting cumulative population exposure. At the herd level, nucleic acid-based detection yielded a pooled detection rate of 44.6% (95% CI: 33.6-55.9), while serological estimates reached 39.0% (95% CI: 14.6-66.3), collectively supporting widespread herd-level circulation. Substantial between-study heterogeneity was largely attributable to temporal, regional, and herd health factors, underscoring how surveillance design and diagnostic strategy can substantially influence reported prevalence and obscure the true scale of viral spread. Collectively, these findings indicate that PEDV is a globally entrenched, persistently circulating pathogen sustained through subclinical infection and herd-level viral persistence. This work provides the first comprehensive global synthesis of PEDV epidemiology and establishes an evidence-based framework to guide standardised surveillance, contextualise diagnostic outcomes, and inform targeted prevention strategies encompassing vaccination and biosecurity. Strengthening harmonised monitoring systems will be essential to reducing the long-term burden of PEDV in modern swine production.