NIGMS-Funded Research Links El Niño to Dengue Fever Epidemics

Screen shot from video
Incidence of dengue fever across Southeast Asia, 1993-2010. Note the increasing incidence of dengue fever (red), starting in June 1997, which corresponded to a period of higher temperatures driven by a strong El Niño season. At the end of the El Niño event, in January 1999, dengue incidence was much lower (green). Credit: Willem van Panhuis, University of Pittsburgh.

A new study by a large international consortium of researchers led by Willem van Panhuis and Don Burke at University of Pittsburgh Graduate School of Public Health has shown that outbreaks of dengue fever are closely linked with events of El Niño, a weather pattern affecting the global climate. El Niño is marked by high sea surface temperatures along the equator in the Pacific, lasting between nine months to two years. Besides increasing the frequency of natural disasters, such as storms, floods, droughts and famine, in far-flung parts of the world, one of El Niño’s major effects is that it brings warm and wet weather to many regions. These conditions provide fertile grounds for the spread of mosquito-borne diseases, such as malaria and dengue.

Dengue fever is caused by infection with a virus and is a leading cause of illness and death in tropical and sub-tropical countries, with an estimated 2.5 billion people at risk for infection. Dengue fever has become a global threat and is endemic or epidemic in almost every tropical country. Its geographical areas have expanded in recent years, leading to spatiotemporal heterogeneity in disease intensity. Therefore, researchers have been trying to develop better methods to forecast dengue outbreaks and to identify the factors that spur dengue virus transmission.

In the study published in the journal Proceedings of the National Academy of Sciences, the researchers analyzed 3.5 million dengue surveillance reports spanning an 18-year period across eight countries in Southeast Asia. Helped by the Models of Infectious Disease Agents Study (MIDAS) program, this network of scientists used computational, statistical and mathematical models to unravel the spatiotemporal dynamics of dengue transmission.

The analysis of this massive surveillance data set revealed that the highest dengue incidence across the monitored regions during 1997-1998 overlapped with increased temperatures due to an El Niño event, followed by a period of extremely low incidence in 2001-2002, coinciding with an absence of El Niño. Furthermore, dengue cycles occurring over 2-to-5-year periods across Southeast Asia were synchronized with increased temperatures associated with El Niño. This international collaborative study aided by the tools and methods developed by the MIDAS program will help improve disease surveillance to predict dengue epidemics in order to have disease controls, such as vaccines, antiviral drugs and advanced diagnostics, in place for future dengue outbreaks.

This work was funded in part by NIH under grants U54GM088491, R01AI102939 and R01AI114703.

van Panhuis WG, Choisy M, Xiong X, Chok NS, Akarasewi P, et al. Region-wide synchrony and traveling waves of dengue across eight countries in Southeast Asia [PDF, 2.4MB] Link to external Web site. Proc Natl Acad Sci USA. 112 (42): 13069-13074.

University of Pittsburgh News Feature: Pitt Public Health Leads International Team in Linking Dengue Epidemics to High Temperatures During Strong El Niño Season Link to external Web site

For additional information, contact Veerasamy "Ravi" Ravichandran.