News Excerpt:
Researchers have found a potential link between anomalies in sea-surface temperatures in the Indian Ocean and the intensity of dengue epidemics globally, offering hope for improved prediction of dengue outbreaks.
Methodology of the study:
- The study published in the journal Science identified a specific indicator, the Indian Ocean basin-wide (IOBW) index.
- IOBW represents the average sea-surface temperature variations across the tropical Indian Ocean.
- In this study, the researchers used data on yearly dengue cases reported from across each of the 46 Southeast Asian and American countries from 1990-2019.
- Data of monthly cases from 24 of these countries reported from 2014-19 was also used for analysis.
- Through modelling, the team drew associations between changes in climate patterns around the world and those in seasonal and yearly case numbers during dengue epidemics.
Key highlights of the study:
- Indian Ocean basin-wide (IOBW) index, according to the study, exhibits a close association with dengue outbreaks in both the Northern and Southern hemispheres.
- The IOBW index’s association with the Southern Hemisphere is stronger than that with the Northern Hemisphere.
- The index has a more pronounced impact on temperatures in tropical regions.
- Brazil, for example, bears a higher burden of dengue in the Southern Hemisphere.
- It demonstrates that the IOBW index substantially affects the local temperature worldwide, influencing dengue transmission.
- These initial findings suggested that the index could be a potential indicator to forecast the interannual and seasonal magnitude of global dengue epidemics.
Current method of forecasting dengue outbreaks:
- Precipitation and temperature are some of the climate indicators that are being used as early warning systems to forecast disease trends such as dengue.
Limitations of the study:
- The team could not fully evaluate the IOBW index as some countries did not have publicly available annual and monthly case reports.
- The study also did not consider other factors that may influence dengue transmission, such as vector control measures, social and economic factors, and local herd immunity.
Way Forward:
- Future research should focus on incorporating other potential factors and establishing a comprehensive set of indicators for a dengue early warning system,
- More data is needed to establish causality, meaning that IOBW influences local temperature changes and the resultant increase in dengue incidence in many countries.
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