El Nino favourable to dengue outbreaks

Copyright: Gilbert Felongco

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  • Study finds high incidence of dengue transmission during El Niño episodes
  • The link with high temperature could help authorities anticipate outbreaks of dengue
  • It could also be useful in strengthening interventions as global temperature rises

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[MANILA] As countries in South-East Asia battle anew rising dengue outbreaks, scientists say they have found a link between El Niño and the increasing incidents of dengue which could help health authorities to map out counter strategies.

A study published in the Proceedings of the National Academy of Sciences tracked cases of the mosquito-borne disease across eight countries in South-East Asia and linked the high incidence of dengue transmission to episodes of El Niño, when temperatures reach higher than normal levels.

“Dengue epidemics during El Niño can be avoided through interventions that are safe as well as through environmental management measures.”

By Lilian Delas Llagas, dengue control specialist

The study observed that outbreaks of the viral disease could be anticipated to a certain measure as it coincides with increases in global temperatures such as during the El Niño Southern Oscillation episodes.

“We detected strong patterns of synchronous dengue transmissions across the entire region, most markedly during a period of high incidence from 1997-1998, the strongest El Niño episode of the century,” notes the study’s senior author Derek Cummings, a biology professor with the Emerging Pathogens Institute at the University of Florida, United States.

In the course of the research, experts collated 3.5 million reported dengue cases from 273 provinces in eight countries in South-East Asia over an 18-year period in 1993-2010.

They also found that dengue outbreaks come in “waves” characterised by a high incidence followed by a dramatic lull in cases on a continental scale across South-East Asia.

The research team also noted their multi-country collaborative study could “improve insight that may lead to improved prediction of dengue transmission patterns and more effective disease surveillance and control efforts”.

“Warmer temperatures cause enhanced viral activity within the carrier, in this case, the Aegis Egyptii mosquitoes,” Lilian Delas Llagas, a dengue control specialist and public health professor at the University of the Philippines, tells SciDev.Net.

“Dengue epidemics during El Niño can be avoided through interventions that are safe as well as through environmental management measures,” she adds.

Some of the simple interventions involve public information drive warning about the disease and how to prevent them, habitual community cleaning, making sure that water containers are covered and removal of potential mosquito breeding grounds.

According to Madeleine Thomson, a scientist with the International Research Institute for Climate and Society at Columbia University in the United States, the current El Niño serves as an “opportunity for public health systems (to show) their ability to handle extreme climate events, which are expected to occur more frequently in the future”.

“Studying climate variability now and understanding better how our climate system works on shorter-term scales will inform the study of how our climate might change on longer-term scales,” she says.

>Link to full paper in Proceedings of the National Academy of Sciences

This article has been produced by SciDev.Net's South-East Asia & Pacific desk.


PNAS doi: 10.1073/pnas.1501375112 (2015)