Rising Zoonotic Threat in Tropics Demands Urgent Action

New Research Highlights Growing Disease Spillover Risks in Tropical Regions

A comprehensive new analysis reveals that tropical regions worldwide are facing escalating risks of zoonotic disease outbreaks, with scientists calling for immediate investments in surveillance systems, land use policy reforms, and enhanced One Health coordination. The findings come as climate change and deforestation accelerate human-wildlife interactions, creating perfect conditions for pathogens to jump from animals to humans.

'We're seeing a perfect storm of environmental change, habitat destruction, and human encroachment into wildlife areas,' says Dr. Maria Rodriguez, an epidemiologist at the Global Health Institute who contributed to the research. 'The data clearly shows that without coordinated action, we're setting ourselves up for more frequent and severe disease outbreaks.'

The Science Behind the Rising Risk

The research, published in the journal One Earth in August 2025, analyzed 312 studies covering 39 different pathogens and diseases. The alarming finding was that only 7.4% of current risk assessments integrate all three essential components: hazard, exposure, and vulnerability. Most studies (52%) focus solely on hazard assessment, leaving critical gaps in understanding how diseases actually spread to human populations.

Landscape composition and temperature emerged as the most significant environmental predictors of disease transmission. Tropical regions, with their high biodiversity, warm climates year-round, and rapid land use changes, are particularly vulnerable. Deforestation for agriculture and urbanization fragments habitats, bringing humans into closer contact with wildlife and their pathogens.

'When you clear a forest for palm oil plantations or cattle ranching, you're not just removing trees,' explains Dr. James Chen, an environmental health researcher. 'You're disrupting entire ecosystems and forcing animals—and the diseases they carry—into human-dominated landscapes. It's a recipe for disease emergence.'

The Surveillance Gap

Current disease surveillance systems in many tropical countries are underfunded and fragmented. The World Health Organization estimates that approximately 60% of known infectious diseases and 75% of emerging infectious diseases have animal origins, yet detection capabilities remain inadequate in many high-risk regions.

The CDC's One Health Zoonotic Disease Prioritization (OHZDP) process has shown promise in helping countries identify their top zoonotic threats through collaborative workshops. However, implementation of surveillance systems based on these priorities requires sustained funding and political commitment that often falls short.

'We have the tools and knowledge to build effective early warning systems,' says Dr. Amina Diallo, a public health specialist working in West Africa. 'What we lack is consistent investment and the political will to maintain these systems between outbreaks. It's like only buying fire insurance when your house is already on fire.'

Land Use Policy: A Critical Lever

The research emphasizes that land use policies represent one of the most powerful tools for preventing zoonotic disease emergence. A study published in Bioscience highlights how human-driven environmental modifications—deforestation, urbanization, agricultural expansion—create conditions that facilitate disease transmission between wildlife, livestock, and humans.

Experts argue for policies that maintain wildlife corridors, protect intact forests, and regulate agricultural expansion into sensitive ecosystems. 'We need to move beyond seeing forests just as timber or land for development,' says environmental policy analyst Sarah Johnson. 'They're critical public health infrastructure. Protecting them is cheaper than dealing with pandemic outbreaks.'

The One Health Imperative

The One Health approach, which recognizes the interconnectedness of human, animal, and environmental health, is increasingly seen as essential for addressing these complex challenges. The Quadripartite Organizations—FAO, WHO, WOAH, and UNEP—have been promoting this integrated framework, but implementation at national and local levels remains inconsistent.

'One Health isn't just a nice concept—it's a practical necessity,' states Dr. Robert Kim, director of a One Health initiative in Southeast Asia. 'When veterinarians, doctors, ecologists, and policymakers work in silos, we miss the connections that lead to disease outbreaks. We need integrated surveillance that monitors wildlife health, livestock diseases, and human illnesses simultaneously.'

The research calls for shifting from reactive to preventive strategies, with better integration of environmental data into public health planning. This includes developing new indicators for disease risk assessment that account for land use changes, climate patterns, and biodiversity loss.

Path Forward

Scientists recommend several immediate actions: increased funding for integrated surveillance systems in tropical regions, development of land use policies that consider disease prevention, strengthening of One Health coordination mechanisms, and capacity building for local health professionals.

'The COVID-19 pandemic showed us the devastating cost of being unprepared,' concludes Dr. Rodriguez. 'We have a window of opportunity to build more resilient health systems that can prevent the next pandemic, not just respond to it. The science is clear—investing in prevention now will save lives and resources in the long run.'

As tropical regions continue to experience rapid environmental change, the urgency of addressing zoonotic disease risks grows. The research serves as both a warning and a roadmap for creating healthier, more sustainable relationships between humans, animals, and their shared environments.