# Climate change and mosquito-borne disease expansion > Live situation record from CLSTR: https://clstr.news/situations/climate-change-and-mosquito-borne-disease-expansion > Updated: 2026-10-25T00:00:00.000Z. Sources: 36. Developments: 5. Climate change and phenomena such as El Niño continue to drive the expansion of mosquito-borne diseases and the proliferation of invasive species. Rising temperatures and altered rainfall patterns create favorable conditions for the Aedes aegypti mosquito and others, such as the tiger, Japanese, and yellow fever mosquitoes. In Brazil, health surveillance in Paranavaí reported 731 suspected and 289 confirmed dengue cases between January and early October 2026. A study by the Oswaldo Cruz Foundation (Fiocruz) indicates that climate change is driving dengue expansion across Brazil, noting that the number of microregions experiencing epidemic levels has more than doubled between 2006 and 2024, now covering 54% of the country. Thermal anomalies are identified as the primary indicator, as warming trends allow mosquitoes to thrive in previously protected regions, such as Rio Grande do Sul, which recorded nearly 210,000 confirmed infections and 281 deaths in 2024. In Bahia, approximately 163,000 cases and 188 deaths were reported. Beyond dengue, other diseases are showing increased geographic spread. Oropouche fever, once largely confined to the Amazon region, saw over 12,000 infections across 23 states last year. Additionally, extreme weather events such as floods have increased risks of waterborne diseases like leptospirosis due to contaminated water supplies. In Europe, changing climate patterns including milder winters and prolonged heat facilitate the spread of invasive mosquitoes in Spain and increase local transmission risks in Portugal. Technological interventions show varying results. While the Incompatible Insect Technique (IIT) using Wolbachia bacteria has been piloted in Rome and Spain, the method has seen significant success in Balneário Camboriú, Brazil, where cases reportedly dropped from 7,106 in 2024 to just 12 in 2026. ## Claims - The number of Brazilian microregions with epidemic dengue levels rose from 110 to 292 between 2006 and 2024. (corroborated by 21 sources) - Thermal anomalies are the best climatic indicator for long-term dengue incidence increases. (corroborated by 19 sources) - Rio Grande do Sul recorded nearly 210,000 confirmed dengue infections and 281 deaths in 2024. (corroborated by 18 sources) - Bahia recorded approximately 163,000 dengue cases and 188 deaths in 2024. (corroborated by 18 sources) - Oropouche fever caused more than 12,000 infections in 23 states last year. (corroborated by 4 sources) - The combination of sufficient heat and abundant water promotes mosquito growth. (corroborated by 3 sources) - Climate changes, including milder winters and prolonged heat, are facilitating the spread of invasive mosquito species in Spain. (corroborated by 3 sources) - There are currently three invasive mosquito species in Spain: the tiger mosquito, the Japanese mosquito, and the yellow fever mosquito. (corroborated by 3 sources) - The tiger mosquito and the yellow fever mosquito are significant health concerns due to their ability to transmit dengue, chikungunya, and Zika. (corroborated by 3 sources) - The activity period of the tiger mosquito has expanded into late autumn and early spring due to milder temperatures. (corroborated by 3 sources) - Balneário Camboriú implemented the Wolbachia method to reduce dengue cases. (single source) - Balneário Camboriú dengue cases fell from 7,106 in 2024 to 12 in 2026. (single source) ## Timeline ### 2026-10-25: Brazil: Climate change drives expansion of infectious diseases Climate change is expanding the reach of infectious diseases in Brazil. Dengue epidemic microregions rose from 110 to 292 since 2006, driven by thermal anomalies and rising temperatures. 26 sources. https://clstr.news/cluster/climate-change-drives-dengue-expansion-across-brazil ### 2026-10-21: Rising mosquito-borne disease risks drive new control technologies and climate studies New technological partnerships and climate studies are addressing the rising threat of mosquito-borne diseases like dengue in Europe and Argentina due to warming temperatures. 2 sources. https://clstr.news/cluster/rising-mosquito-borne-disease-risks-drive-new-control-technologies-and-climate-studies ### 2026-10-15: El Niño and climate change drive rising dengue outbreak risks Studies show El Niño and climate change increase dengue risk by 23.70%, with human activity driving nearly half of new outbreaks by expanding mosquito habitats through temperature and humidity shifts. 2 sources. https://clstr.news/cluster/el-nio-and-climate-change-drive-rising-dengue-outbreak-risks ### 2026-10-11: Spain faces rising risk from invasive mosquito species Invasive mosquito species, including the tiger and yellow fever mosquitoes, are expanding in Spain due to warmer climates, increasing the risk of diseases like dengue and Zika. 4 sources. https://clstr.news/cluster/spain-faces-rising-risk-from-invasive-mosquito-species ### 2026-10-05: Climate change and El Niño drive rise in dengue fever risks Climate change and the El Niño phenomenon are driving the spread of dengue fever by creating ideal breeding conditions for the Aedes aegypti mosquito in regions including Brazil and Portugal. 2 sources. https://clstr.news/cluster/climate-change-and-el-nio-drive-rise-in-dengue-fever-risks --- Cite as: Climate change and mosquito-borne disease expansion. CLSTR, https://clstr.news/situations/climate-change-and-mosquito-borne-disease-expansion