Dengue fever, a mosquito-borne disease, has become an increasing global public health concern, with climate factors playing a crucial role in its transmission. A recent study led by Professor KIM Jae Kyoung from the Korea Advanced Institute of Science and Technology (KAIST) and the Biomedical Mathematics Group at the Institute for Basic Science (IBS) has provided new insights into how temperature and rainfall influence dengue outbreaks. The research reveals that variations in dry season length significantly impact the effects of rainfall on dengue transmission, offering a more refined understanding of how climate change may exacerbate the spread of mosquito-borne diseases.
Dengue cases have risen alarmingly in recent years. According to the World Health Organization (WHO), reported cases surged from 4.1 million in 2023 to more than 10.6 million in 2024 in North and South America alone. This dramatic increase underscores the urgency of understanding how environmental factors contribute to the disease’s spread. While it is well known that temperature and rainfall influence mosquito populations and, consequently, dengue transmission, previous studies have struggled to establish clear causal relationships due to conflicting results. Some research suggests that rainfall promotes mosquito breeding by creating stagnant water pools, while other studies indicate that heavy rainfall washes away breeding sites, thus reducing mosquito populations.
The IBS research team tackled this challenge by employing General ODE-Based Inference (GOBI), an advanced causal inference framework they developed in 2023. Unlike traditional methods that examine climate factors in isolation, GOBI captures nonlinear and combined effects of temperature and rainfall on dengue incidence. This innovative approach allowed researchers to uncover a more nuanced relationship between weather conditions and dengue outbreaks.
Focusing on 16 regions in the Philippines, the study identified distinct dengue regulation patterns across various climatic zones. One key finding was that rising temperatures were consistently associated with higher dengue incidence. However, the impact of rainfall varied significantly by region. In some areas, increased rainfall led to a rise in dengue cases, while in others, it had a suppressive effect.
A major breakthrough in the study was identifying the variation in dry season length as a crucial factor explaining the differing effects of rainfall on dengue outbreaks. In regions where the dry season length remained relatively stable, heavy rainfall helped flush out mosquito breeding sites, thereby reducing dengue transmission. Conversely, in areas where the dry season length fluctuated significantly, intermittent rainfall created new mosquito breeding habitats while reducing the flushing effect, leading to increased mosquito populations and higher dengue incidence.
This discovery highlights the need to consider dry season length as a key variable in predicting dengue outbreaks. Unlike previous studies that focused primarily on temperature and total rainfall, this research demonstrates that the timing and variability of dry seasons play a crucial role in shaping mosquito population dynamics.
To validate these findings, the researchers extended their analysis to Puerto Rico, a region with diverse climatic conditions. Data from cities such as San Juan, Adjuntas, and Ponce confirmed similar dengue regulation patterns, reinforcing the generalizability of the study’s conclusions.
According to first author Olive R. Cawiding, “Our findings provide robust evidence for how climatic factors influence dengue transmission in diverse environments. This represents a significant step toward understanding how climate change may impact mosquito-borne diseases globally.”
Beyond dengue, these insights could also inform strategies for controlling other climate-sensitive infectious diseases such as malaria, Zika virus, and influenza. By applying the GOBI framework to different regions and disease systems, researchers can develop more precise models for predicting and mitigating disease outbreaks driven by climate variability.
The study’s findings have important implications for dengue control efforts. For regions with stable dry seasons, natural flushing effects from heavy rainfall may reduce the need for intensive mosquito control measures during the rainy season. In contrast, areas with highly variable dry seasons require consistent year-round intervention strategies to counteract the increased mosquito breeding opportunities created by sporadic rainfall.
Public health agencies can use these insights to allocate resources more effectively, prioritizing interventions in high-risk areas based on their unique climatic patterns. Additionally, monitoring dry season length could serve as an early-warning indicator for dengue outbreaks, enabling governments to take proactive measures before cases escalate.
While this study provides valuable insights into climate-driven dengue dynamics, the researchers acknowledge some limitations. The absence of mosquito population data and socioeconomic factors such as healthcare accessibility and human movement may have influenced the results. Future studies incorporating more granular data, including weekly dengue incidence rates and mosquito density, could further refine these findings.
Chief Investigator KIM Jae Kyoung emphasized the broader significance of the study, stating, “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. This approach can also be applied to the analysis of various diseases linked to climate.”
The link between climate and dengue fever is complex, with temperature, rainfall, and dry season variability playing interconnected roles in shaping disease transmission. By leveraging innovative analytical methods, this study provides a clearer understanding of how weather patterns influence dengue outbreaks and offers actionable strategies for mitigating the disease’s impact. As climate change continues to alter global weather patterns, such research will be critical in shaping public health policies and improving disease control efforts worldwide.
