New Information on Climate Drivers of Dengue Fever

*Original version of this release posted by Upstate Medical University

Researchers from Upstate Medical University, Columbia University’s International Research Institute for Climate and Society and other U.S. and international institutions have discovered new information on the climate drivers of dengue fever and social risk factors that may be contributing to its spread. Their findings were published in the open-access journals BMC Infectious Disease and BMC Public Health.
The work could help public health officials develop dengue early-warning systems that incorporate both climate and non-climate information, as well as create targeted public-health programs to promote community engagement in dengue control.

Dengue, a mosquito-borne viral illness, is a leading cause of illness in the tropics and subtropics. Cases of the disease have been reported in the United States and Western Europe. Dengue is transmitted to people primarily by the Aedes aegypti mosquito, which reproduces in containers with standing water in and around homes. There is currently no vaccine or cure for dengue, and so public health agencies are keen to identify alternative strategies to manage the disease.
The research teams conducted the two studies in the urban coastal city of Machala, Ecuador, an area where dengue is prevalent, and the site of ongoing dengue research by Upstate Medical University and partners.
“This work provides insights into the complex climate and social factors that trigger dengue outbreaks, contributing to efforts to develop a dengue early warning system,” said Upstate researcher Anna M. Stewart Ibarra, who is also the Latin America Research Program Director for Upstate’s Center for Global Health & Translational Science.
“We also found that social and political conditions have to be considered when designing dengue control interventions, especially for high-risk, marginalized populations,” said Stewart Ibarra.
The team found that a confluence of unusually high rainfall and minimum temperatures were associated with the dengue outbreak, and that this confluence happens on timescales of one to two years.

“The key idea is that these two climate variables aren’t always in phase, but when they are, we can have an epidemic in coastal Ecuador,” said coauthor Ángel Muñoz, from the International Research Institute for Climate and Society. “Monitoring the phase difference between minimum temperature and rainfall may allow us to identify suitable conditions for an outbreak months ahead of time. This could be a key component of a  dengue early-warning system.”

In the second study, researchers also found that risk factors included households headed by women, and among other factors, the combination of poor housing conditions and access to piped water, likely due to water storage practices in areas where water supply interruptions are frequent. This study, which didn’t include IRI researchers, used focus groups to assess community perceptions of dengue fever. Researchers identified persistent misconceptions that limited people’s ability to take actions to prevent dengue. Social cohesion and political access were also major dengue risk factors, especially in low-income communities where people were unable to mobilize the resources needed to prevent disease outbreaks. They highlighted the need for dengue interventions that target the most vulnerable populations, and the importance of strong collaborations with local municipal governments and community leaders.