Influence of climate and heatwaves on dengue transmission in Sao Paulo and Natal, Brazil

PLOS One | https://doi.org/10.1371/journal.pone.0334838 October 24, 2025 10 / 13 long-term analysis in Rio de Janeiro indicated that epidemics were more likely when minimum temperatures exceeded 22 °C and summers were both hot and dry, highlighting temperature as a primary driver of seasonal transmission [61]. In addition, Alves et al. [62] applied a mechanistic SEI–SIR model in multiple Brazilian cities using satellite-derived tempera- ture and rainfall inputs, capturing key features of the seasonal dengue cycle and the role of temperature-driven vertical transmission. These studies collectively underscore the importance of temperature – often in conjunction with rainfall – as a critical climatic factor influencing dengue outbreaks in Brazil. However, most have focused on average temperatures or lagged seasonal patterns rather than on the health effects of extreme heat events. Our study contributes to this literature by explicitly assessing the impact of heatwaves, a dimension largely overlooked in previous Brazilian models. This event- based approach adds important insights into how short-term climatic extremes may disrupt mosquito ecology and dengue transmission dynamics, complementing existing knowledge built on long-term temperature trends. This study faced several limitations. First, dengue cases may have been underreported, as infections are not always documented at onset, resulting in a misalignment between the timing of exposure and case reporting. Second, our reli-

ance on weekly data constrained our ability to accurately capture the initiation, duration, and frequency of heatwaves and their specific impacts on dengue incidence. Third, unmeasured factors – such as exposure assessment methods, land use patterns, and other environmental, social, and demographic variables – may have contributed to the observed vari- ability. For instance, Schmidt et al. [63] found that infrastructural shortcomings (e.g., inadequate water supply) had a more pronounced effect on dengue transmission in Vietnam than climatic factors. Fourth, the lack of data prevented us from stratifying our analysis by dengue serotype, an area that future studies should address. Lastly, our analysis did not con- sider the potential influence of local dengue control programs, which could significantly affect annual infection rates. The effectiveness of interventions such as Natal’s VigiDengue program and São Paulo’s Municipal Dengue Control Program (PMCD) warrants further investigation and could explain some of the observed variations in dengue incidence [64,65]. Conclusions Our findings suggest that dengue incidence increases in association with rising minimum temperatures, whereas elevated maximum temperatures, the occurrence of heatwaves, and higher cumulative rainfall are associated with reduced trans- mission. These patterns underscore the need for an integrated, multisectoral approach to arboviral disease control – one that bridges human health, vector ecology, and environmental dynamics. Both São Paulo and Natal exhibited distinct

patterns in dengue distribution. Notably, the effects of extreme heat events, particularly heatwaves, on dengue transmis- sion remain poorly understood. Addressing this critical knowledge gap will be essential to inform adaptive public health strategies and ensure regionally tailored responses under a changing climate. Supporting information S1 File. Database with dengue cases and climate variables from the municipalities of São Paulo/SP and Natal/RN used in this study. (XLSX) Author contributions Conceptualization: Camila Lorenz, Rita Yuri Ynoue, Adriana Gioda, Thiago Nogueira. Data curation: Camila Lorenz. Formal analysis: Camila Lorenz. Funding acquisition: Camila Lorenz, Rita Yuri Ynoue, Adriana Gioda, Thiago Nogueira. Investigation: Camila Lorenz, Rita Yuri Ynoue, Adriana Gioda, Thiago Nogueira. Methodology: Camila Lorenz.