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

Abstract

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.