Dengue hotspot mapping can identify risk of Zika and Chikungunya – PCT
Data from nine cities in Mexico confirms that identifying dengue hotspots can provide a predictive map of future Zika and chikungunya outbreaks. These viral diseases are spread by the yellow fever mosquito, Aedes aegypti.
Lancet Planetary Health published the research, led by Gonzalo Vazquez-Prokopec, associate professor in the Department of Environmental Sciences at Emory University. The study provides a risk stratification method to more effectively guide the control of diseases spread by Aedes aegypti.
“Our findings can help public health officials carry out targeted and proactive interventions for Aedes– transmitted diseases, ”said Vazquez-Prokopec. “We provide them with statistical frameworks in the form of maps to guide their actions.
The study included data from 2008 to 2020 from cities in southern Mexico with a high burden of dengue cases during this period, as well as cases of more recently emerged diseases like Zika and chikungunya. The cities included Acapulco, Merida, Veracruz, Cancun, Tapachula, Villahermosa, Campeche, Iguala and Coatzacoalcos.
The results revealed a 62 percent overlap of hotspots for dengue and Zika and a 53 percent overlap for dengue and chikungunya cases. In addition, dengue hotspots between 2008 and 2016 were significantly associated with dengue hotspots detected between 2017 and 2020 in five of the nine cities.
The work builds on a previous study of the spatiotemporal overlap of the three diseases, focused on Merida, a city of one million people located in the Yucatan Peninsula. This study showed that almost half of the dengue cases of Mérida from 2008 to 2015 were grouped in 27% of the city. These dengue hotspots contained 75 percent of the first cases of chikungunya reported during the outbreak of this disease in 2015 and 100 percent of the first cases of Zika reported during the Zika outbreak of 2016.
“In this latest article, we broadened our analysis in terms of scope and geography and showed that the results are consistent across these nine cities of different sizes and across different regions,” said Vazquez-Prokopec. “We have confirmed that dengue, Zika and chikungunya epidemics tend to concentrate in small areas of a city and that these hot spots are predictive of where future cases will concentrate.”
Mosquito control efforts typically involve an outdoor spray that covers large areas of a city, but the Aedes aegypti the mosquito has adapted to live indoors. The work of Vazquez-Prokopec and colleagues has shown that the best way to control these mosquitoes and the diseases they spread is to spray a long-lasting pesticide indoors: on ceilings, along walls and in other areas of houses where mosquitoes tend to congregate.
This approach, known as targeted indoor residual spraying, is too expensive and time-consuming to apply in a city.
However, the statistical framework in this document allows public health officials to focus their efforts on past hot spots of Aedes– transmitted diseases to better control – and even prevent – epidemics.
“The ultimate goal is to empower public health officials to harness big data and fight mosquitoes more effectively and efficiently, even before an epidemic begins,” said Vazquez-Prokopec.
Vazquez-Prokopec is currently leading a consortium in a randomized clinical trial in Merida to test targeted indoor residual spraying as an intervention against Aedes– transmitted diseases. The five-year trial, launched in 2020, is funded by a $ 6.5 million grant from the National Institutes of Health.
Dengue fever is sometimes referred to as “bone-breaking fever” because of the excruciating pain among its symptoms. More than a third of the world’s population lives in areas at high risk for infection with the dengue virus, one of the leading causes of illness and death in the tropics and subtropics.
Dengue is endemic in much of Mexico, where between 75,000 and 355,000 cases occur each year, which translates into an economic cost of around $ 150 to 257 million per year.
Chikungunya is rarely fatal, but the symptoms can be severe and debilitating. Zika can cause symptoms similar to dengue and chikungunya, such as joint pain and fever. While Zika tends to be less debilitating, if not asymptomatic, if a pregnant woman contracts the virus it can have a catastrophic impact on her unborn child, including serious brain deformities.