Contact tracing, with indoor spraying, can curb dengue outbreak

By Carol Clark | eScienceCommons | Feb. 22, 2017

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A public health worker collects Aedes mosquito larvae from water that has pooled on a tarp at a residence in Cairns, Australia.

Contact tracing, combined with targeted, indoor residual spraying of insecticide, can greatly reduce the spread of the mosquito-borne dengue virus, finds a study led by Emory University.

In fact, this novel approach for the surveillance and control of dengue fever – spread by the same mosquito species that infects people with the Zika virus – was between 86 and 96 percent effective during one outbreak, the research shows. By comparison, vaccines for the dengue virus are only 30-to-70-percent effective, depending on the serotype of the virus.

Science Advances published the findings, which were based on analyses from a 2009 outbreak of dengue in Cairns, Australia.

“We’ve provided evidence for a method that is highly effective at preventing transmission of diseases carried by the Aedes aegypti mosquito in a developed, urban setting,” says the study’s lead author, Gonzalo Vazquez-Prokopec, a disease ecologist in Emory’s Department of Environmental Sciences. “We’ve also shown the importance of human movement when conducting surveillance of these diseases.”

“The United States is facing continual threats from dengue, chikungunya and Zika viruses,” says Sam Scheiner, director of the National Science Foundation’s Ecology and Evolution of Infectious Diseases Program, which funded the research. “For now, the response is to intensively spray insecticides. This research shows that a more targeted approach can be more effective.”

While the method would likely not be applicable everywhere, Vazquez-Prokopec says that it may be viable to control Aedes-borne diseases in places with established health systems and similar environmental characteristics to Cairns, such as South Florida or other U.S. states at risk of virus introduction.

“The widespread transmission of dengue viruses, coupled with the birth defects associated with Zika virus, shows the dire need for as many weapons as possible in our arsenal to fight diseases spread by these mosquitos,” he says. “Interventions need to be context dependent and evaluated carefully and periodically.”

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