What’s driving emerging plant and animal pests and diseases?
From crop failures to animal epidemics to zoonotic diseases, new pests and diseases are emerging more often – and spreading more widely than before. These threats don’t just affect agrifood systems. They impact the health of plants, animals, people, and the environment, requiring a One Health approach to manage them.
So, what’s causing them?
Behind each outbreak are underlying drivers – these are some of the main ones:
One of these is climate change, which is shifting the natural ranges of pests, vectors, and pathogens. For example, fall armyworm, once confined to the Americas, has now spread across Africa, Asia, and the Near East - devastating maize and other staple crops. In animal health, warming temperatures have contributed to extending the range of vector-borne diseases like West Nile Fever, affecting both animals and people.
Deforestation and land-use change are also major contributors. As forests are cleared, people, livestock, and wildlife come into closer contact. This raises the risk of zoonotic spillover, where diseases jump from animals to humans – just as Nipah virus, maintained in bats, has infected pigs and people in farming areas across Asia.
Pests and diseases can travel across borders via air or sea in mail and courier systems.
Left/top: © FAO/Khalil Mazraawi. Right/Bottom: ©FAO/Genya Savilov
Meanwhile, global trade, travel and informal movements enable plants, animals, and products to circulate faster than ever – along with the pests and pathogens that travel with them. FAO has tracked the spread of banana Fusarium wilt TR4 across continents through infected planting material, while diseases like peste des petits ruminants (PPR) have spread internationally through movements of small ruminants.
Monocultures – where large areas are planted with a single crop – amplify these risks. In banana plantations, genetic uniformity has made Cavendish bananas especially vulnerable to TR4.
Finally, gaps in surveillance and coordination make it harder to detect and contain emerging threats. Many countries may lack integrated early warning systems that connect plant, animal, and human health services. This can slow down responses and increases the risk of spread.
These drivers are complex - but not impossible to manage. Understanding them is the first step to preventing future crises.
A new space for collaboration
To help connect the dots and support early action, and knowledge into action, FAO has launched a new Community of Practice on drivers of emerging plant and animal pests and diseases, including zoonotic spillover, hosted in the One Health Knowledge Nexus.
This global platform brings together stakeholders working across agriculture, health, and environment to explore why new threats are emerging, share tools and lessons for prevention and collaborate across sectors before the next outbreak hits.
Join the Community and support advancing the One Health approach. Because preventing the next outbreak starts with understanding what’s driving current ones.