Mérida in center of dengue ‘hot spots’ study

The state's campaign against mosquito larvae has begun, and residents have been largely receptive. Handout photo
State brigades go door to door to fight the spread of mosquitos in Yucatán. 2016 file photo

Mérida, Yucatán — The city was used as a model in a study by the U.S. Centers for Disease Control and Prevention, as well as Mexican health officials and researchers, on predicting future dengue and other mosquito-borne outbreaks.

An Emory University team has found that surveillance of dengue outbreaks can better predict where the new pathogens are going to spread.

The strength of the overlap means it is a model that could lead to smarter responses to head off outbreaks, said Gonzalo Vazquez-Prokopec, an Emory disease ecologist who is the lead author.

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“The results open a window for public health officials to do targeted, proactive interventions for emerging Aedes-borne disease,” said Vazquez-Prokopec. “We’ve provided them with a statistical framework in the form of a map to guide their actions.”

The focus of the study was the city of Mérida and its population of about a million people

The 40,000 dengue cases from 2008 to 2015 were clustered. About half were in neighborhoods hot spots taking up 27 percent of the city, the researchers found.

These hot spots were also the first appearances of the the chikungunya and Zika virus that followed the dengue outbreak.

About 75 percent of the chikungunya cases were centered there in 2015, and all of the Zika cases in 2016, their first appearance, were accounted for in those same neighborhoods.

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Blood tests of 5,000 people showed that people living within the hot spots showed twice the rate of viral infection from those outside the locations.

The Aedes aegypti mosquito is particularly difficult to stop because it has adapted to urban environments. One of its tactics is to live inside houses, avoiding outdoor spraying by health officials.

Key areas could be tactically targeted for indoor residential spraying, according to the paper.

“Although effective vaccines would be the ultimate line of defense against these diseases, we cannot give up on mosquito control,” said Vzquez-Prokopec. Inoculations for chikungunya and Zika have not yet been developed.

Dengue fever was originally reported in the Americas as early as the 1600s, brought by colonialism and the winds of war and trade. Ever since, it has appeared intermittently in the warmer climate of the Western Hemisphere, carried by the Aedes aegypti mosquito.

Source: Science Daily

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