Financial incentives have become increasingly popular for promoting pro-social, pro-environmental, and health-promoting behaviors worldwide. As these incentives are now being considered in One Health contexts—settings characterized by the interdependence of human, animal, and ecosystem health—important questions remain about how to maximize their effectiveness while minimizing unintended consequences. A comprehensive review published in Science in One Health synthesizes over two decades of research on financial incentives for behavior change, revealing both the promise and pitfalls of using these tools at the intersection of human, animal, and environmental health.
Evidence on effectiveness and key challenges
Meta-analyses and systematic reviews provide strong evidence that conditional financial incentives are effective in promoting health-related behaviors in the short term. However, evidence for long-term sustainability beyond 18 months remains limited. Payment for ecosystem services programs similarly show numerous successful examples, though benefits are typically modest and highly dependent on contextual factors including governance capacity, property rights security, and monitoring mechanisms.
The literature reveals several persistent challenges. (1) Ensuring additionality—that incentives produce behavior change that would not have occurred otherwise—remains difficult to discern in practice. (2) Monitoring compliance proves challenging for complex, repeated behaviors; simple, easily observable actions like disease reporting are far more amenable to incentives. (3) A fundamental distinction exists between collective versus individual behaviors. Some desirable actions require collective effort, yet designing effective group incentives is considerably more complicated than targeting individuals, depending on internal group governance and unified understanding of commitments. (4) Behavioral incentive programs can inadvertently exacerbate social equity concerns by recruiting primarily influential residents or discouraging existing livelihoods without providing alternatives. (5) Moral hazard can arise when payment structures inadvertently incentivize undesired behaviors. For example, rewards based on quantity can accidentally encourage overfishing or increased animal breeding. (6) Income effects present a subtle but serious concern in low-income countries where payments might constitute an important income source. If recipients fear the incentive's disappearance after program success, they may surreptitiously support disease persistence, particularly if they do not perceive the target disease as a severe threat.
Critical knowledge gaps
Beyond these challenges, six major unknowns persist. The interaction between incentives and communication campaigns is poorly documented, despite evidence that carefully designed communication can enhance behavior uptake. Motivation crowding effects remain inconsistently understood—financial incentives may undermine intrinsic motivation in some contexts (crowding-out) or enhance other motivations in others (crowding-in). The relative effectiveness of cash versus non-cash incentives remains uncertain, with some evidence suggesting non-monetary rewards can be effective while avoiding motivation crowding concerns. The precise role of conditionality (requiring behavior verification for payment) remains debated. Long-term effects after incentives end are poorly understood—whether behavior persists due to habituation and social norm internalization or declines due to crowding-out effects. Finally, designing collective incentives remains poorly understood; participating in collective payment schemes has strengthened governance in some communities while exacerbating conflict in others.
Guinea worm disease: a One Health case study
Guinea worm disease provides a compelling example of financial incentives in One Health contexts. Designated for global eradication in 1986, when it affected approximately 3.5 million people annually across 21 countries, the disease has experienced dramatic success—declining by 99.9% to just 15 human cases by 2024. However, animal infections now pose new challenges. First detected in domesticated dogs in Chad in 2012, by 2024 there were 664 animal cases across six African countries, with more cases occurring annually in animals than humans since 2014.
National Guinea Worm Eradication Programs (GWEPs) have implemented three main financial incentive strategies. Cash rewards for reporting human cases align well with evidence-based principles—reporting is an individual action, easily verifiable, with strong individual benefits. Reward amounts have increased substantially from US$10 to several hundred dollars (equivalent to weeks' or months' income), reflecting the high stakes of complete eradication.
Incentives for reporting infected animals present more complexity. In Chad, when rewards were provided on a per-animal basis, unintended consequences emerged: some households increased dog ownership hoping to benefit from infected animals, leading to stray dog populations and disputes over reward eligibility. The program restructured incentives to a household basis coupled with community awareness campaigns, reducing perverse incentives while motivating reporting.
Incentives for proactive dog tethering (confining animals to prevent water source access) confront additional challenges. While animal movement is easily observable to local people, monitoring by outsiders requires sustained local surveillance. Communities have been empowered to decide how rewards are distributed, with some directing incentive funds to community-level pools supporting public goods. Chad's program provides approximately US$5 monthly per household meeting specified criteria, demonstrating careful design to motivate behavior without creating an expected income source.
Design principles for One Health contexts
The alignment between Guinea worm eradication practices and research evidence suggests core principles for successful incentive design. Target behaviors must be easily monitorable and not already incentivized by existing markets. Reward amounts should be high enough to motivate but not so high as to become perceived as regular income. Incentives must integrate with community participation and communication efforts that build understanding of program objectives. Local decision-making should be empowered rather than top-down, and programs should anticipate and design against perverse incentive effects through careful research and monitoring.
Conclusion
While financial incentives offer potential for promoting behavior change in One Health contexts, they are not always appropriate. Meta-analyses demonstrate that incentives typically produce only modest effects, are highly dependent on contextual factors, and their long-term impacts remain unknown. When proposed incentive programs cannot align with research-based design principles—addressing additionality, monitoring capacity, collective action challenges, equity concerns, and long-term effects—alternative approaches emphasizing community engagement, communication, and infrastructure development should probably be pursued instead.
Success in One Health requires deep contextual understanding, robust monitoring, adaptive management, and genuine community partnership. When implemented carefully with appropriate caution and alongside proper communication grounded in understanding of community social norms and practices, financial incentives can contribute meaningfully to One Health objectives as part of comprehensive programs supporting behavior change through multiple complementary pathways.
