Yellow fever is a vector-borne disease with substantial epidemic potential currently concentrated in Africa and Latin America. This scoping review sought to map the published literature that projects future trends in yellow fever epidemiology or vector evolution at the intersection of climate change, climate variability and human behaviour, and to synthesise recurring trends that may influence the future spread of yellow fever.
Systematic searches were performed in PubMed, Embase and Cochrane CENTRAL from database inception to September 2024, with additional manual searches of congress abstract books in September 2024. The review followed Joanna Briggs Institute scoping review methodology and used PRISMA-ScR guidance for reporting.
Studies qualified for inclusion if they reported original data on projected future trends in yellow fever disease, virus or vector dynamics in relation to climatic factors and/or human behaviour. Review articles and reports without original data, or those not addressing future trends in this specific context, were excluded.
A total of 1,243 records were screened and 42 studies met the inclusion criteria. The earliest included study dated from 2009, and 67% of included studies were published between 2019 and 2024. Most included studies (81%) were modelling studies, reflecting a predominance of projection and forecasting approaches across the dataset. Data were manually extracted into a bespoke Excel form and final categorisation and interpretation were determined by expert manual review; generative AI was used only as a drafting aid during trend identification.
Across the included literature, the most consistent signal was a projected climate-driven expansion in the range and abundance of major yellow fever vectors, particularly Aedes aegypti. Studies most frequently evaluated temperature and precipitation as covariates influencing vector suitability, survival and distribution.
Model outputs generally suggested that warming temperatures and changing precipitation patterns could increase the geographic range and local abundance of competent vectors. However, the evidence base was dominated by modelling assumptions and scenario choices, and the studies varied in geographic focus, temporal horizons and modelling frameworks.
Human-related factors were commonly incorporated into models as amplifiers of exposure risk. In particular, urbanisation and population growth were repeatedly modelled as increasing the pool of susceptible humans and facilitating vector–human contact. Land-use change and other behavioural or socioeconomic drivers were also considered in several studies, often as modifiers of vector habitat availability or human exposure patterns.
These findings indicate that human activities and demographic trends may interact with climatic changes to elevate the potential for human exposure to yellow fever vectors, particularly in urban or peri-urban settings where Aedes aegypti thrives.
While many studies projected increases in vector range and abundance, fewer studies directly linked these projections to future yellow fever transmission or incidence. Among studies that did attempt to model transmission, results were more heterogeneous, reflecting variability in model structure, transmission assumptions, vaccination coverage considerations and the complex role of enzootic (sylvatic) cycles.
Consequently, although a majority of analyses suggest that increases in human exposure and transmission risk are plausible outcomes of climatic and behavioural changes, direct empirical or modelled evidence tying vector expansions to consistent increases in yellow fever epidemics is limited within the included literature.
The review highlighted several important evidence gaps at the intersection of climate, behaviour and yellow fever dynamics:
These gaps limit the ability to draw robust, generalisable conclusions about future epidemic risk and location-specific transmission outcomes.
The body of primary literature reviewed suggests that changing climatic conditions and human activities—including urbanisation and land-use change—are likely to contribute to increases in yellow fever vector abundance and geographic range, most prominently for Aedes aegypti. Many analyses imply that such vector changes will elevate human exposure and transmission risk, yet direct evidence linking vector projections to future yellow fever epidemics is less frequent and shows heterogeneity across studies.
Policy and research implications derived from the review include the need for more empirical and modelling work linking vector suitability projections to transmission outcomes, expanded attention to non-Aedes vectors and sylvatic cycles, and increased geographic focus on Africa. The review’s classification relied on expert manual interpretation of extracted data; where details were not provided in the source literature, this summary reports that those details were not available in the included studies.