A systematic review of more than 200 studies published in BMC Infectious Diseases on human viruses over more than a century suggests that viral emergence peaked from 1950 to 1979 and again starting in 2000, with most initially detected in the United States, China, and Australia.
For the study, researchers from the University of New South Wales in Sydney, Australia, conducted a systematic review of 212 human viruses reported from 1900 to 2024 to determine temporal trends, geographic origins, modes of transmission, and clinical syndromes. The team also developed a novel visualization tool for exploring viral patterns interactively.
“Over the past century, the emergence and re-emergence of infectious diseases ranging from HIV/AIDS and SARS [severe acute respiratory syndrome] to Zika virus, COVID-19, and Mpox, have repeatedly challenged health systems, exposed gaps in surveillance infrastructure, and disrupted economies and societies,” the study authors wrote.
“These events highlight the reality that pathogen emergence is not a rare anomaly but an ongoing process influenced by an increasingly interconnected and ecologically fragile world,” they added.
Country-level differences in tracking, research capacity
A total of 87 viruses emerged from 1950 to 1979, and another 54 were first detected beginning in 2000, the latter making up 25.5% of emerging pathogens since the 20th century. Peaks corresponded to advancements in molecular diagnostics, lab infrastructure, and global surveillance networks.
The most common initial detection sites were the United States (42 viruses), China (15), and Australia (10), which the investigators said reflects differences in surveillance and research capacity rather than geographic differences.
Our findings highlight how technological, ecological, and socio-demographic factors shape viral emergence.
RNA viruses such as influenza and coronaviruses were common, and vector-borne and zoonotic pathogens made up 62% of emerging infectious diseases. Febrile illnesses made up 27.4% of infections, and respiratory and hemorrhagic diseases were also prevalent, at 25.5% and 14.2%, respectively.
“Our findings highlight how technological, ecological, and socio-demographic factors shape viral emergence,” the authors wrote. “The interactive visualization tool provides a resource for understanding historical trends, informing risk assessment, and guiding future surveillance strategies.”
New opportunities for pathogens to jump species
The team noted that pathogen emergence is driven by a mixture of biologic, ecologic, and anthropogenic factors, including climate change.
“Zoonotic spillover has been implicated in many emerging infectious diseases (EIDs) in humans,” they wrote. “Increased human-animal interaction, driven by urbanization, deforestation, agricultural intensification, and the wildlife trade, has created new opportunities for pathogens to jump species barriers.”
While genomic surveillance, environmental sampling, artificial intelligence, and open-source intelligence tools have been integrated into global surveillance systems, early emerging virus detection is often delayed by fragmented data sources, underreporting, a lack of standardization, and the unpredictability of novel pathogen features, the researchers said.
“Consequently, there remains a pressing need for tools that can consolidate historical emergence data, visualize trends, and support predictive modelling,” they wrote. “Strengthening vaccination programs, maintaining robust surveillance, and fostering interdisciplinary collaboration will be essential to mitigate future epidemic and pandemic tasks.”
