International air travel and human mobility are the most visible aspect of globalization linked to pandemics, but the aspect that most contributes to causing them is the global expansion of industrial agriculture and livestock trade. The distinction matters: moving people around the world spreads existing infections faster, but the way globalization reshapes land use, animal farming, and food supply chains is what creates new pandemic-capable pathogens in the first place.
Understanding which forces actually generate pandemic risk, versus which ones accelerate it, helps explain why outbreaks keep emerging despite improved surveillance and faster communication.
Industrial Livestock and the Birth of New Pathogens
Most pandemics begin as zoonotic events, where a pathogen jumps from animals to humans. Globalized agriculture drives this process in two reinforcing ways: it pushes farming into wildlife habitats, and it concentrates enormous numbers of animals in conditions ideal for viral evolution.
The Nipah virus outbreak in Malaysia in 1998 is a textbook case. A 30,000-unit intensive pig farm was established in a deforested area where fruit bats lived. The bats dropped urine and chewed fruit from trees overhanging the farm, passing the virus to pigs below. The pigs acted as amplifier hosts, enabling transmission to humans and killing more than 100 people. Extensive regional trade of infected animals then spread infections further. This sequence, habitat disruption followed by intensive farming followed by trade networks, repeats across outbreaks worldwide.
Illegal poultry trade between countries in Southeast Asia played a significant role in the continued spread of avian influenza H5N1 across the region. Legal trade creates the same channels. When global demand for cheap protein drives the construction of massive livestock operations in tropical areas rich in bat and bird diversity, it systematically manufactures opportunities for spillover. The global wildlife trade, estimated at hundreds of billions of dollars annually, adds another layer. Even the illegal portion, valued at roughly 10% of the legal market, is considered one of the most valuable illicit industries in the world, and it moves live animals across borders with minimal biosecurity screening.
Air Travel Turns Local Outbreaks Into Global Ones
Once a pathogen makes the jump to humans, the global aviation network determines how fast it spreads. A person carrying an infection in one location can reach virtually any other point on the planet in one to two days. That speed outpaces the incubation period of most respiratory viruses, meaning infected travelers often arrive at their destination before they feel sick or become identifiable.
SARS in 2003 demonstrated this vividly. The virus spread from southern China to 29 countries over roughly eight months, producing 8,096 probable cases and 774 deaths, a case fatality rate of 10%. COVID-19 followed the same playbook at far greater scale. In country after country, the leading urban centers were among the first to register cases because they were the most connected to international air routes.
Research on 20 major cities in the Global South found that international air connectivity, participation in international trade, and urban density all predicted higher early exposure to COVID-19. Cities with the lowest percentage of international air arrivals, like Antofagasta in Chile and Quetzaltenango in Guatemala, saw the least increase in caseloads during the early phase of the pandemic. Meanwhile, major hubs like Santiago and Accra, which receive nearly all incoming international travelers for their countries, were hit hardest and earliest.
Air travel is often called the most obvious manifestation of globalization’s role in pandemics. Experts at a National Institutes of Health workshop on globalization and infectious disease noted that while increased human mobility may be the most obvious link, it is by no means the most important. Speed of spread matters enormously, but it is secondary to the forces that generate new pathogens.
Global Trade and Urbanization Create Vulnerability
The broader engine of globalized capitalism reshapes societies in ways that compound pandemic risk. As global commodity demand grows, forests are cleared for agriculture, displacing wildlife and increasing human contact with animal reservoirs of disease. Cities swell as people move toward economic opportunity, creating dense populations where respiratory pathogens thrive. Supply chains link rural production zones to urban trade hubs to international airports in a seamless chain that a virus can ride from a bat cave to a megacity in days.
Urbanization itself is not a single risk factor but a multiplier. Dense living conditions, crowded transit systems, and informal settlements with limited sanitation all increase transmission once a pathogen arrives. Research found that primate cities (the dominant urban center in a country) tend to carry a higher share of national caseloads than non-primate cities, likely because of their outsized role in international commerce and travel.
How These Forces Work Together
No single aspect of globalization causes a pandemic alone. The process works in stages, and each stage is driven by a different dimension of global integration:
- Pathogen emergence: Global demand for food, timber, and animal products drives deforestation and intensive livestock farming in biodiversity-rich tropical regions, creating conditions for viruses to jump from wildlife to domestic animals to humans.
- Local amplification: Rapidly growing cities with high population density allow a new pathogen to establish sustained human-to-human transmission before it is even identified.
- Global dissemination: International air travel and trade networks carry the pathogen to every continent within weeks, far faster than public health systems can mount a coordinated response.
The first stage is the most consequential because it is where novel threats are born. Without spillover events, the other stages have nothing to amplify. And spillover is accelerating: the same economic pressures that created the conditions for Nipah, SARS, avian influenza, and COVID-19 are intensifying as global meat consumption rises and agricultural frontiers push deeper into remaining forests.
What the International Response Looks Like
Global institutions have begun to address these interconnected risks, though progress is slow. In June 2024, the World Health Assembly reached consensus on amendments to the International Health Regulations, creating a new legal framework for pandemic preparedness that will enter into force in September 2025. Under the revised rules, the WHO Director-General can now declare a “pandemic emergency” as a distinct category, and member states have committed to facilitating access to vaccines, diagnostics, and treatments during emergencies, particularly for lower-income countries.
A separate WHO Pandemic Agreement focuses on international coordination for prevention, preparedness, and response. It includes plans for a Global Supply Chain and Logistics Network to distribute health products equitably during crises, and a Pathogen Access and Benefits Sharing system currently being negotiated for the 2026 World Health Assembly. That system aims to ensure scientists can access pathogen samples and genetic data quickly while guaranteeing that resulting vaccines and treatments reach the countries that need them most.
These frameworks primarily address the response side of the equation: what happens after a pathogen emerges. The harder challenge is reducing spillover risk at its source, which requires confronting the economic incentives that drive deforestation, wildlife trade, and intensive animal farming in high-risk ecosystems. Until those upstream pressures are addressed, globalization will continue generating new pandemic threats faster than institutions can prepare for them.