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Merida, Yucatan Mexico, March 22, 2015: Horse carriages with passengers on a city street in Merida, Mexico. (Credit: photoshooter2015/Shutterstock.com)

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.

Two other diseases have emerged in the Americas since 2013: the chinkungunya and Zika viruses, both of which are carried by the same parasite. Now an Emory University team has found that surveillance of dengue outbreaks can better predict where the new pathogens are going to spread, according to a new study.

The study of a major city on the Yucatan Peninsula in Mexico involved the U.S. Centers for Disease Control and Prevention, as well as Mexican health officials and researchers, they report in the latest issue of PLOS Neglected Tropical Diseases.

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.

“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 Merida, with a population of approximately 1 million, report the scientists.

The 40,000 dengue cases from 2008 to 2015 were clustered, with about half clumped together in neighborhoods taking up approximately 27 percent of the city, the researchers found.

These “hot spots” were also the first appearances of the two new viruses. About 75 percent of the chikungunya cases were centered in these hot spots in 2015, and 100 percent of the Zika cases in 2016, their first appearance, were accounted for in those same neighborhoods.

A follow-up test of laboratory 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, according to the paper.

The Aedes aegypti mosquito is particularly difficult to stop, since it has adapted to urban environments. One of its tactics is to live inside houses, where it can feed on hosts—and avoids outdoor spraying by health officials.

But the new findings indicates that key areas could be tactically targeted for indoor residential spraying, according to the paper. Inoculations for chikungunya and Zika, after all, have not yet been developed.

“Although effective vaccines would be the ultimate line of defense against these diseases, we cannot give up on mosquito control,” said Vzquez-Prokopec.

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