Systematic Review and Meta-Analysis of Emerging Viral Zoonotic Diseases, 2016-2026

Emerging viral zoonoses-infections caused by viruses that cross the species barrier from animal reservoirs into human populations-account for the majority of emerging infectious disease (EID) events and now constitute a defining threat to global health security. Over the past decade the tempo of these spillovers has increased, propelled by land-use change, agricultural intensification, wildlife trade, and climate change, while reverse zoonosis-the transmission of human pathogens back into animal populations-has created novel animal reservoirs capable of seeding future outbreaks. Against this backdrop, we systematically reviewed and meta-analyzed epidemiological evidence on emerging viral zoonoses from January 2016 through June 2026, searching five bibliographic databases and synthesizing 312 included studies. Annual high-consequence spillover events increased by 4.98% (95% CI 3.22%-6.76%), and the decade saw five Public Health Emergency of International Concern (PHEIC) declarations, alongside other high-consequence spillovers such as the 2026 Bundibugyo virus outbreak (case fatality rate [CFR] 30.9%) and the expansion of H5N1 highly pathogenic avian influenza into dairy cattle. Bat-origin viruses exhibited the highest pooled CFR (29.86%), whereas primate-origin viruses demonstrated greater transmissibility, supporting a virulence-transmissibility trade-off. Land-use change emerged as the dominant anthropogenic driver, increasing zoonotic host diversity by 18%-72%. White-tailed deer SARS-CoV-2 seroprevalence reached 32.7% (95% CI 21.4%-46.1%), with confirmed deer-to-human spillback. Nonpharmaceutical interventions (NPIs) collectively reduced the effective reproduction number by up to 82%, and prevention-oriented One Health strategies yielded returns exceeding 1100% on investment. Viral zoonoses are accelerating under anthropogenic pressure, and upstream prevention with integrated One Health surveillance represents the most cost-effective pandemic preparedness strategy.