Climate change may worsen tuberculosis risks

Tuberculosis remains the world’s leading infectious disease killer, but it has been largely missing from broader conversations about climate and health. Commissioned by the World Health Organization, Christopher Finn McQuaid and colleagues set out to make the connections easier to see. Rather than testing a single hypothesis in new field studies, the team developed an analytical framework to map how climate change could affect the many social, biological and environmental factors that drive tuberculosis. They began by reviewing what is already known about the determinants of tuberculosis — including poverty, crowding, nutrition, migration and health system strength — and then asked which of those determinants are likely to be sensitive to changes in climate. The researchers then built mechanistic pathways showing how altered weather patterns, extreme events and longer-term climate shifts could translate into greater risk of tuberculosis transmission, progression from infection to disease, or barriers to diagnosis and treatment. Their goal was to create a structured way to guide future research and policy, so that tuberculosis would no longer be overlooked in climate health planning.

To construct the framework the team drew on existing knowledge about tuberculosis determinants and used targeted literature reviews to gather evidence for each proposed pathway. They identified which determinants are plausibly climate-sensitive and then conceptualised mechanistic routes linking climate effects to tuberculosis outcomes. The literature reviews served to test whether any direct empirical studies already existed that measured the relationship between climate change and tuberculosis. The result was striking: the researchers found no studies that directly link climate change to tuberculosis outcomes. Nevertheless, the available indirect evidence supported the existence of plausible links — for example, climate-driven food insecurity or displacement could worsen malnutrition and crowding, both known drivers of tuberculosis. The synthesis therefore highlights plausible causal chains and pinpoints where empirical evidence is missing, supporting the need for focused research to quantify actual effects.

The analysis has practical implications for how health systems, funders and policymakers respond to climate risks. Because the review found plausible but unquantified links, tuberculosis should be included in climate risk assessments, adaptation planning and mitigation programmes rather than treated as an unrelated issue. Integrating tuberculosis into climate-resilient funding and response mechanisms could mean prioritising surveillance in climate-vulnerable areas, protecting supply chains for diagnosis and treatment after extreme events, and directing research funds to measure how climate impacts disease burden. Crucially, McQuaid and colleagues call for new empirical studies to fill the evidence gaps identified by their framework; without quantification of effect sizes and clearer causal estimates, it will be difficult to design the most effective interventions. The framework therefore aims to move tuberculosis from the periphery of climate-health debates into the mainstream of planning and research priorities.