Dengue in a Warming and Increasingly Wet World: When Higher Temps and Unusual Rainfall Mean Higher Dengue Risk

In recent years, we've witnessed a troubling trend: dengue fever is on the rise, and climate change is playing a significant role in its spread. Higher temperatures speed up the virus's development inside mosquitoes, shortening the time it takes for a mosquito to become infectious after biting an infected person [1,2]. Increasing rainfall results in the gathering of water and the creation of puddles in open spaces, which in turn provides perfect conditions for mosquito populations to multiply.

The consequences of these climate-driven changes are being felt worldwide. Regions that once saw only occasional dengue cases are now experiencing regular outbreaks. Meanwhile, areas where dengue was already endemic are seeing more intense and frequent epidemics.

In South America, dengue incidence has surged over the past two decades. This increase correlates with rising temperatures and more days with optimal conditions for dengue transmission. One example is Brazil which has seen a continuous transmission of dengue since 1986, with high incidence rates correlating with elevated temperatures and precipitation volumes [3]. 

The El Niño phenomenon, characterized by abnormal warming of Pacific Ocean waters, has also been associated with increased dengue outbreaks in coastal regions of Peru and Ecuador, where the climatic conditions favor the mosquito's habitat and breeding sites [4]. In Colombia, unusually high temperatures during El Niño years have been shown to significantly increase dengue cases, with temperature having a more substantial impact than precipitation [5].

Dengue cases have also experienced a significant upswing across the Asian region. In Bangladesh, a surge in dengue fever cases has been associated with elevated temperatures and increased precipitation. The most pronounced rise in cases is noted when the mean temperatures hover between 28°C and 30°C [6]. In Malaysia, climate factors such as temperature, rainfall, humidity, and wind speed have been statistically linked to dengue incidence, with wind speed showing the most significant impact [7]. In Yogyakarta, Indonesia, fluctuations in rainfall, air temperature, and humidity significantly affect dengue cases, highlighting the intricate interplay between various climatic factors and dengue transmission.

The complex and region-specific nature of the climate-dengue relationship is seen in the United States where the impact of rising temperatures on dengue transmission varies by region. Cities like Los Angeles and Houston are experiencing increased dengue risk due to warming temperatures. However, in cities like Miami, Brownsville, and Phoenix, extreme heat has paradoxically reduced the risk of dengue. 

The relationship between temperature and dengue is context-dependent, with positive correlations observed at intermediate temperatures around 24°C, especially in areas with high-temperature variation and population density [8]. Rainfall, while not always directly correlated with dengue cases, can create breeding sites for mosquitoes, particularly in urban areas with inadequate infrastructure and water storage practices, as seen in Espírito Santo and other Brazilian cities [3,9].

The rise of dengue fever is a stark reminder of the profound impact climate change has on public health. As temperatures soar and rainfall patterns shift, the breeding grounds for Aedes mosquitoes expand, leading to increased dengue transmission worldwide.

The interplay between higher temperatures and unusual rainfall patterns necessitates targeted public health interventions and early warning systems. Understanding these climate-driven changes is crucial for preparing and responding to the escalating threat of dengue fever.

Climate change is reshaping the infectious disease landscape, with dengue fever as a prime example. Warmer temperatures and erratic rainfall patterns are the perfect storm for mosquito breeding. As we navigate through this warming and increasingly wet world, our resilience will be tested, but with proactive measures and adaptive strategies, we can protect our communities from dengue’s escalating threat.

References

[1] Mercier A, Obadia T, Carraretto D. et al. Impact of temperature on dengue and chikungunya transmission by the mosquito Aedes albopictus. Sci Rep 12, 6973 (2022). https://doi.org/10.1038/s41598-022-10977-4. 

[2] Dengue | CDC Yellow Book 2024

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[4] Cristian Díaz-Vélez, Jorge Luis Fernández-Mogollón, John A Cabrera-Enríquez, Stalin Tello-Vera, Oscar Medrano-Velásquez, Elmer Córdova-Calle. Situation of Dengue after the Phenomenon of the Coastal El Niño. undefined (2020). doi: 10.5772/INTECHOPEN.92095

[5] Adriana Lorena, Sanchez, Nazly E, Sánchez, Andrés Mauricio, Gómez Sánchez. Climatic phenomenon and meteorological variables influencing the dengue fever incidence in Colombian South Pacific region: Modeling study. Annals of Tropical Medicine and Public Health, undefined (2017). doi: 10.4103/ATMPH.ATMPH_395_17

[6] Mohammad Nayeem Hasan, Ibrahim Khalil, Muhammad Abdul Baker Chowdhury, Mahbubur Rahman, Md Asaduzzaman, Masum Billah, Laila Arjuman Banu, Mahbub-Ul Alam, Atik Ahsan, Tieble Traore, Md Jamal Uddin, Roberto Galizi, Ilaria Russo, Alimuddin Zumla, Najmul Haider, Two decades of endemic dengue in Bangladesh (2000–2022): trends, seasonality, and impact of temperature and rainfall patterns on transmission dynamics, Journal of Medical Entomology, Volume 61, Issue 2, March 2024, Pages 345–353, https://doi.org/10.1093/jme/tjae001

[7] Childs ML, Lyberger K, Harris M, Burke M, Mordecai EA. Climate warming is expanding dengue burden in the Americas and Asia. medRxiv [Preprint]. 2024 Jan 9:2024.01.08.24301015. doi: 10.1101/2024.01.08.24301015. PMID: 38260629; PMCID: PMC10802639.

[8] Devin Kirk, Samantha Straus, Marissa L, Childs Mallory J, Harris Lisa I, Couper T, Jonathan Davies, Coreen Forbes, Alyssa-Lois M, Gehman Maya L, Groner Christopher, D G Harley, Kevin D, Lafferty, Van M, Savage, Eloise B, Skinner, Mary I, O'Connor Erin A, Mordecai. Temperature impacts on dengue incidence are nonlinear and mediated by climatic and socioeconomic factors. bioRxiv, undefined (2022). doi: 10.1101/2022.06.15.496305.

[9] Carolina, Cristina, Bicalho., Iraziet, da, Cunha. The influence of climatic factors on dengue epidemies in the cities cuiab a (mato grosso state) and lavras (minas gerais state), brazil, using statistical methods. undefined (2013).