World One Health Congress Update: The Conversation Is Moving From Principle to Delivery

One day into the 9th World One Health Congress in Lisbon, an interesting theme is becoming increasingly difficult to miss: the case for One Health is no longer the most important argument in the room. The harder question is becoming how we make it work.

Delegates have gathered in Lisbon for four days of scientific presentations, policy discussions and workshops spanning human, animal and environmental health. Yesterday’s opening established an ambitious agenda around moving One Health from knowledge towards action. Today’s programme begins testing what that actually means — governance, preparedness, implementation, interdisciplinary working, systems thinking, surveillance, financing. These are not as conceptually appealing as another declaration that human, animal and environmental health are interconnected. They may be considerably more important.

From One Health advocacy to One Health governance

One of today’s central sessions asks an unusually direct question: One Health Governance: where does the EU stand? The plenary examines progress from scientific recommendations towards implementation, including what has actually been achieved and what delivery looks like on the ground.

That distinction matters. One Health has accumulated strategies, frameworks, declarations and institutional commitments. The existence of those frameworks is important, but ultimately the effectiveness of One Health cannot be measured by the number of organisations that endorse the principle. It has to be measured by what changes when a biological threat crosses sectors. When an emerging livestock pathogen appears, can veterinary and public-health surveillance communicate? When environmental conditions change vector distributions, does that information influence health preparedness? When genomic surveillance identifies an unusual cluster, can epidemiology and traceability turn that signal into intervention? When wildlife, livestock and people share an epidemiological system, can our institutions see the same system? Those are governance questions, and increasingly they are the questions One Health needs to answer.

Preparedness is becoming a One Health capability

Today’s programme also includes a presentation reflecting on ten years of EU partnership for preparedness and resilience across regions. That language is significant. Preparedness is sometimes treated as an inventory — laboratories, diagnostics, stockpiles, surveillance systems, response plans — but it is better understood as a capability. The question is not simply whether those components exist. It is whether they can function together when required. A laboratory capable of sequencing pathogens is valuable. A veterinary surveillance network is valuable. Environmental monitoring is valuable. Public-health epidemiology is valuable. But a One Health security system emerges only when information and action can move between them. That is where preparedness becomes resilience.

Yesterday provided several reminders of why this matters

The opening scientific programme illustrated just how difficult it is to separate contemporary biological threats into neat sectors. Researchers presented work on the climate-driven expansion of Vibrio vulnificus, using genomics to investigate environmentally persistent pathogenic lineages. Other sessions considered swine influenza A virus in Europe and cross-sector pathogen surveillance. Work on rabies examined how viral genomics can identify local transmission patterns and inform elimination strategies, and another presentation examined dogs carrying highly pathogenic Campylobacter jejuni with potential relevance across species. Different pathogens, different hosts, different environments — but structurally similar problems. The biological system crosses boundaries more easily than the institutions responsible for observing it.

The environment can no longer sit outside health security

The environmental component of One Health has historically been the easiest part to acknowledge and one of the hardest to operationalise. Climate change is making that increasingly untenable, since changes in temperature, rainfall, water systems and ecosystems can alter the geography and seasonality of vectors and pathogens. We have seen a small but instructive example in Britain this week: UK health authorities detected Aedes aegypti mosquitoes breeding in east London for the first time. That finding does not mean Britain is facing a dengue or Zika outbreak, and the current public-health risk remains very low. But it demonstrates why environmental and entomological surveillance increasingly belongs inside health-security planning — the relevant chain runs from environmental change, through vector suitability, introduction and establishment, to pathogen introduction and local transmission. Intervening earlier in that sequence is considerably preferable to intervening at the end. One Health provides the conceptual framework. Operational surveillance has to provide the capability.

Emerging animal disease provides another test

Germany is currently providing another example. Laboratory sequencing has identified two genetically distinct Shamonda-related orthobunyavirus variants circulating in the country, representing apparently independent introduction events. Both belong to the Simbu serogroup, both now overlap geographically, and they are circulating alongside Schmallenberg virus. Important questions remain unresolved, including host range, potential reproductive consequences, cross-protection between variants and the consequences of co-circulation between related segmented viruses. Again, the problem cannot be reduced to virology — understanding the event requires veterinary surveillance, vector ecology, genomics, farm observations, epidemiology and risk assessment working together. The important resource is not simply another dataset. It is the ability to combine those observations quickly enough to understand what is changing.

Systems thinking is appearing explicitly

One of today’s workshops is devoted to the One Health Mural, an interactive systems-thinking tool intended to strengthen multisectoral understanding of complex health challenges. That may sound peripheral beside pathogen genomics and outbreak surveillance. It isn’t. One Health problems are fundamentally systems problems. Consider antimicrobial resistance: antibiotic use in people cannot be considered entirely separately from veterinary antimicrobial use, and neither can be separated completely from pharmaceutical manufacturing, wastewater, agriculture, environmental contamination, microbial ecology or access to appropriate diagnostics. Similarly, zoonotic emergence cannot be understood solely through pathogen biology — land use, agricultural production, wildlife ecology, human behaviour, trade, climate and health-system capacity can all influence risk. The challenge is therefore not simply acquiring more specialist knowledge. It is understanding how specialist knowledge connects.

And tomorrow the Congress widens the lens further

The programme for 6 September moves strongly into biodiversity, wildlife and pathogen interfaces, with sessions on integrated One Health surveillance combining field sampling, molecular diagnostics, serology, genomics and ecological monitoring. Other presentations address diagnostics moving from innovation towards field readiness, virus–host interactions, and high-consequence viral transmission in natural reservoirs. That progression is important: surveillance is increasingly moving away from finding a pathogen and identifying its host, towards understanding the biological system in which emergence occurs — combining field observations, genomes, serology, ecology, environmental measurements, animal-health data and human-health data. The resulting surveillance system is considerably richer. It is also considerably harder to govern.

The money question is coming

For One Health Security, however, one of the most interesting parts of the Congress still lies ahead. Monday’s programme contains a Science Policy Interface session explicitly titled Building the Investment Case for One Health: Evidence and Return on Investment from Country Implementation, involving FAO and WOAH representatives. That language deserves attention. For years, One Health advocates have explained why cross-sector collaboration makes biological sense. Increasingly, policymakers are asking a different question: what does it buy us? If governments invest in integrated surveillance, what capability is created? If they improve veterinary diagnostic capacity, what risks are reduced? If environmental monitoring provides earlier warning, how much earlier? If sectors share surveillance infrastructure, what duplication is avoided? If outbreaks are detected earlier, what health and economic losses might consequently be prevented? These are difficult questions. They are also necessary ones.

The Economics of Prevention problem

They are also closely related to the subject of our next Monthly Review, The Economics of Prevention. One reason prevention remains difficult to fund is that its successful outcome often looks like nothing happening. An outbreak detected and contained early may never become a national emergency. A pathogen prevented from entering a livestock population generates no mass cull. A mosquito population eliminated before establishment produces no epidemic. A diagnostic capability maintained for years may appear expensive until the day it is required. The cost is visible. The avoided consequence is counterfactual. That creates a persistent bias towards paying for response after harm becomes visible rather than paying for capability before it does. The investment discussions in Lisbon suggest that One Health is beginning to confront this problem much more directly.

We need to measure capability, not simply spending

This also suggests a better way of thinking about prevention economics. Imagine a government spends €10 million on integrated One Health surveillance. That number tells us very little by itself. The important questions are what capability that €10 million created: did laboratory turnaround improve, did geographic coverage increase, were additional animal populations monitored, did environmental signals become available, did sectors begin sharing information, did detection happen earlier, did decision-makers receive information sooner, did intervention happen faster? Only then can we ask the difficult final question — what consequences might that capability have prevented? The analytical chain runs from investment, through capability, to a change in detection or response, a change in risk, and potential avoided consequences. That is the logic we are beginning to explore through the proposed OHS Prevention Ledger, discussed further in our companion analysis on veterinary medicines and market incentives.

Return on investment needs humility

There is a danger here too. One Health should not respond to demands for economic evidence by manufacturing spectacular return-on-investment numbers from weak assumptions. A model claiming that every €1 invested in prevention saves €20 may be attractive to policymakers, but it is only useful if the evidence supporting that claim is credible. Prevention economics needs to distinguish carefully between observed outcomes and modelled outcomes, between measured costs and estimated avoided costs, and between evidence and assumption. Uncertainty should be visible rather than hidden inside a headline number — especially for low-frequency, high-consequence biological events, where we may never know exactly what an intervention prevented. That does not make prevention valueless. It means we need better ways of describing uncertainty.

One Health is entering its harder phase

Perhaps that is the emerging message from Lisbon. The intellectual case for One Health has largely been won: human health is connected to animal health, both are connected to environmental systems, pathogens cross species, vectors respond to climate, food systems connect farms to populations, and antimicrobial resistance moves through multiple biological and environmental pathways. The harder phase begins when we ask who is responsible, who shares the data, who pays, which capability should be built first, how we know it worked, what happens when institutional priorities conflict, and how much prevention is enough. Those questions are less elegant than drawing three overlapping circles. They are also where One Health becomes real.

The 9th World One Health Congress continues through 7 September. For One Health Security, the sessions to watch most closely now are not simply those demonstrating another connection between humans, animals and environments. They are the ones asking what we are prepared to do about those connections — because the future of One Health will not be decided by whether we understand the concept. It will be decided by whether we can turn that understanding into capability, investment and action.

Questions & Answers

References

1. Global One Health Community (2026). 9th World One Health Congress — Scientific and Science–Policy Programme. Lisbon, 4–7 September 2026.
2. World Health Organization (2026). The 9th World One Health Congress.
3. Food and Agriculture Organization of the United Nations (2026). Quadripartite at the 9th World One Health Congress.
4. WHO, FAO, UNEP & WOAH (2022). One Health Joint Plan of Action (2022–2026).