Unpredictable changes in climate may bring mosquito-borne disease outbreaks years earlier than expected, according to a new study published in the Proceedings of the National Academy of Sciences (PNAS). Scientists warn that governments must strengthen surveillance and preparedness to counter this growing risk.
Researchers examined the impact of internal climate variability (ICV) the natural year-to-year swings in temperature and weather patterns on the spread of vector-borne diseases (VBDs) such as dengue. The study found that ICV significantly increases uncertainty in predicting when and where outbreaks will occur, with fluctuations potentially accelerating the appearance of suitable conditions for disease transmission.
Mosquito Risks Expanding Globally
Climate change has already altered the spread of disease-carrying mosquitoes. Aedes mosquitoes, which transmit dengue, are now appearing in regions previously unaffected. In recent years, local dengue transmission was reported near Los Angeles and Paris, and Aedes albopictus mosquitoes were detected in the United Kingdom for the first time.
Using long-term projections for London between 2030 and 2080, researchers combined temperature data with mosquito transmission models. They discovered that ICV could account for nearly half of the uncertainty in predicting the number of days suitable for dengue transmission. For instance, when factoring in ICV, the risk of London experiencing at least 120 days of dengue-suitable conditions could emerge as early as 2038 nearly a decade earlier than models that ignore ICV.
Preparedness Needed for Public Health
The findings underscore the importance of including ICV in climate and health models. By ignoring natural fluctuations, projections may underestimate how soon disease outbreaks can occur.
Scientists stress that the results carry urgent public health implications. They recommend proactive steps such as vector surveillance at entry points, mosquito breeding site control, improved clinical testing, public awareness campaigns, and robust outbreak response strategies.
The study also noted that future research should expand to include other factors like rainfall, humidity, population density, and local intervention strategies to create more policy-relevant projections.
The authors conclude that without factoring in climate variability, the world may be underestimating how fast mosquito-borne diseases can spread—leaving populations unprepared for the next outbreak.