Ubydul Haque, an assistant professor of global health at Rutgers Global Health Institute, examined data from Mexico's Ministry of Health to pinpoint dengue infection hotspots. The researchers evaluated environmental and socioeconomic risk variables and mapped locations where severe epidemics occur in collaboration with epidemiologists from the University of North Texas and Universidad Autonoma de Nuevo Leon.
The research was published in the journal Ecological Informatics.
"These maps can aid health officials in targeting fogging activities or enhancing surveillance," Haque said. "Knowing where severe dengue fever frequently occurs can significantly reduce the number of cases."
Dengue fever has been reported in 28 of 32 states in Mexico, and researchers have long known that socioeconomic status and weather affect dengue fever case counts in those states. But the factors contributing to disease severity haven't been studied.
Past work also has failed to account for the geographic distribution of variants or serotypes. There are four dengue virus serotypes -- DENV-1, DENV-2, DENV-3 and DENV-4 -- and transmissibility and lethality differ by each.
To fill these research gaps, Haque analyzed laboratory-confirmed dengue fever infections from 71,059 individuals in 2,469 Mexican municipalities collected between 2012 and 2020. Samples included serotype classification.
This data was overlaid with localized weather and socioeconomic statistics, such as literacy, access to health services, electricity and sanitation.
As expected, each degree Celsius increase in temperature was associated with lower rates of occurrence of the virus -- mosquito eggs don't hatch well in high heat -- while increasing humidity was associated with an increase in the rate of each virus serotype.
Moreover, the researchers determined that lower socioeconomic status increases the risk of dengue fever, and indicators such as access to education, information and infrastructure are better predictive factors of dengue fever distribution.
From this data, the researchers produced heat maps highlighting dengue virus distribution and severity. Hotspots were generally observed in humid coastal regions at lower altitudes. Throughout the country, the most prevalent serotype was DENV-2 and the least pervasive was DENV-4, Haque said.
While efforts are underway to develop DENV-specific vaccines, mosquito control programs such as fogging, and drone surveillance remain the most effective means of slowing the disease's spread. Haque said data visualization can help health officials plan where to target their activities.
"From our data, we know that DENV-2 is deadlier compared to other serotypes," Haque said. "If regional health officials had limited resources for their control program, they could focus most of their resources in places where DENV-2 was prevalent."
The WHO estimates dengue fever infects as many as 400 million people yearly, killing thousands. With climate change predicted to increase dengue fever cases in Mexico over the coming decades, continuous surveillance of serotype patterns will be essential to preventing or slowing the rate of increase, Haque said. (ANI)