Bioethics Blogs

Climate and Viral Illness: El Niño Event Linked to Dengue Epidemics


Caption: Incidence of dengue fever across Southeast Asia, 1993-2010. Note increasing incidence (red) starting about June 1997, which corresponds to a period of higher temperatures driven by a strong El Niño. At the end of the El Niño event, in January 1999, dengue incidence is much lower (green). Credit: Wilbert Van Panhuis, University of Pittsburgh

Just as the severity of the winter flu fluctuates from year to year in the United States, dengue fever can rage through tropical and subtropical regions of the world during their annual rainy seasons, causing potentially life-threatening high fever, severe joint pain, and bleeding. Other years—for still unknown reasons—dengue fizzles out. While many nations monitor the incidence of dengue within their borders, their data aren’t always combined to track outbreaks across wider regions over longer times.

Now, NIH-funded researchers and colleagues, reporting in Proceedings of the National Academy of Sciences [1], have linked an intense dengue epidemic that struck eight Southeast Asian countries starting in mid-1997 to high temperatures driven by the strongest El Niño event in recent times. El Niño is a complex, irregularly occurring series of climate changes in the Pacific Ocean with a global impact on weather patterns. This new insight into climatic factors associated with dengue transmission could enable better prevention measures, which may soon be needed because climatologists are predicting another strong El Niño event next year due to unusually high ocean temperatures in the equatorial Pacific.Dengue is a viral infection transmitted by Aedes (meaning “odious” in Greek) mosquitoes. The infection, usually lasting about a week, is rare in the continental United States and typically associated with travel to tropical and subtropical regions.

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