Temperature and precipitation drive dengue fever dynamics worldwide

Temperature and precipitation drive dengue fever dynamics worldwide

The research team led by Kim Jae Kyoung, Professor of the Department of Mathematical Sciences at Kaist and Chief Investigator of the Biomedical Mathematics Group at the Institute for Basic Science (IBS), has presented new insights into the spread of dengue fever. Their study identifies temperature and precipitation as critical factors driving the global increase in dengue cases and offers actionable strategies to mitigate the impact of the disease.

Dengue fever, a mosquito-borne disease, poses an increasingly alarming public health challenge. According to the World Health Organization, dengue cases rose to over 10.6 million in the Americas in 2023 alone. This number is the highest global number ever reported. While climatic factors such as temperature and precipitation are known to drive this trend, their complex relationship to dengue dynamics is poorly understood. Previous studies have struggled to reconcile conflicting results – some suggesting precipitation suppresses dengue transmission, while others indicate it suppresses it.

The IBS research team hypothesized that these inconsistencies arise from the limitations of traditional methods that focus on linear relationships or independent effects. To address this, researchers used GOBI (general ODE-based inference), a novel causal inference framework developed by the IBS group in 2023. This method captures both nonlinear and combined effects of climatic factors and allows for a more nuanced analysis of the relationship between weather and dengue incidence.

The study focused on 16 regions of the Philippines, selected for their different climatic conditions, to examine how temperature and precipitation together influence dengue dynamics. There have been varying patterns of dengue regulation in the Philippines, driven by the combined effects of temperature and precipitation. Rising temperatures were consistently associated with higher dengue incidence across all regions. On the other hand, precipitation showed contrasting effects depending on the location of the region. In eastern areas, rainfall increased dengue incidence, while in western regions, rainfall suppressed it.

The most important factor emerged as variation in dry season length, which was identified as critical in explaining the contrasting effects of rainfall. In regions with little variation in dry season length, rainfall tended to flush out stagnant water, reduce mosquito breeding sites, and suppress dengue transmission. On the other hand, sporadic rainfall in regions with high variation in dry season length caused new breeding sites and weakened the flushing effect, leading to an increase in mosquito populations and dengue cases.

The role of dry season length has been largely overlooked in previous research, but emerged as a critical factor in this study. This discovery offers a new perspective on the complicated relationship between rainfall and dengue dynamics.

To validate their findings, the researchers expanded their analysis to Puerto Rico, a region with different climates. Data from municipalities such as San Juan, Adjuntas, and Ponce showed similar regulatory patterns, underscoring the generalizability of the results.

Our results provide robust evidence on how climatic factors influence dengue transmission in different environments. This represents a significant step toward understanding how climate change may impact mosquito-controlled diseases worldwide. “

Olive R. Cawide, first author

The results of the study have immediate applications for optimizing dengue intervention strategies. For regions with low variation, natural flushing effects during the rainy season can enable scaled intervention efforts and free up resources for other priorities. In particular, in regions with high variation, consistent and year-round intervention efforts are required to counteract the breeding-friendly conditions created by sporadic rainfall.

Furthermore, the study highlights the importance of monitoring dry season length as a predictive factor for dengue outbreaks. By aligning strategies with specific regional climate patterns, public health authorities can allocate resources more efficiently and effectively to combat the spread of dengue.

The study represents a significant turning point in understanding how climate change affects not only dengue fever, but also other climate-related diseases such as malaria, influenza and the Zika virus.

CI Kim Jae Kyoung stated: “This research is crucial as it overcomes the limitations of traditional methods for detecting nonlinear relationships and clearly elucidates the complex interactions between climatic variables and infectious diseases through an advanced causal inference algorithm.

While the study provides robust insights, researchers acknowledge certain limitations, including the lack of mosquito population data and socioeconomic factors such as accessibility and human mobility. Future studies with access to more detailed data such as weekly dengue incidence and mosquito dynamics could further refine these results.

The study, titled “Disentangling Climate’s Dual Role in Dengue Dynamics: A Multi-Region Causal Analysis Study,” was published online inScience advancesa sister Journal of Science.

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