A study has found that climate change is fueling the spread of dengue fever in the Philippines. This analysis was conducted by domestic researchers using mathematics to examine climate and health data in the Philippines over the past five years.
Researchers from the Institute for Basic Science (IBS) and the Korea Advanced Institute of Science and Technology noted that the spread of dengue fever in the Philippines is closely related to the duration of the dry season. The research findings were published online on the 13th in the journal Science Advances.
Dengue fever is an infectious disease transmitted by tropical mosquitoes in subtropical and tropical regions with high temperatures and humidity. According to the World Health Organization (WHO), the number of infections increased nearly tenfold from 500,000 in 2000 to 5.2 million in 2019 over a span of 20 years. Due to climate change, abnormal heat and extreme rainfall have continued, leading to an increase in mosquito breeding and a higher risk of dengue fever infection.
However, there has been longstanding debate in academia about the impact of rainfall on the occurrence of dengue fever. Some studies analyze that an increase in rainfall leads to a greater breeding ground for mosquitoes, raising the risk of infection, while others indicate that heavy rains may wash away mosquito habitats, potentially lowering the risk of infection.
Researchers analyzed monthly dengue fever infection numbers from the Department of Health in the Philippines from 2015 to 2019, along with climate data from 16 regions provided by the Korea Meteorological Administration. Previous studies employed statistical models that assumed temperature and rainfall influence dengue fever occurrence independently, but this study applied a new causal inference technique called 'GOBI (General ODE-Based Inference)' to analyze the complex effects of temperature and rainfall on the spread of dengue fever.
As a result, rising temperatures increased the occurrence of dengue fever in all regions. The impact of rainfall varied based on the variability in the length of the dry season in different areas. In the relatively consistent dry regions of western Philippines, there was a tendency for dengue fever infections to decrease as rainfall increased. Conversely, in the eastern regions where the length of the dry season was irregular, dengue fever occurrences increased with higher rainfall.
These differences are attributed to changes in rainfall patterns and mosquito habitats. In regions with a consistent dry season, preventive measures can be taken before the onset of the rainy season, and heavy rains can effectively wash away mosquito habitats. In contrast, in regions with irregular dry seasons, sudden rains create environments conducive to mosquito breeding, increasing the risk of dengue fever infection. These results were similarly observed in three areas of Puerto Rico.
Based on this research, the researchers stated that "in regions with a consistent dry season, concentrating preventive resources just before the rainy season is effective due to the washing away of mosquito habitats during heavy rains," adding that "in inconsistent dry regions, continuous preventive activities are necessary throughout the year due to the high likelihood of lifelong mosquito habitats forming."
Kim Jae-kyung noted that "the influence of a consistent dry season on the occurrence of dengue fever was an overlooked factor in previous studies," and expressed hope that this research would be a critical turning point in understanding the impact of climate change on climate-sensitive diseases such as dengue fever, malaria, influenza, and the Zika virus.
References
Science Advances (2025), DOI: https://doi.org/10.1126/sciadv.adq1901