Mapping Mexico’s dengue fever hotspots
One in every five dengue deaths in the Americas occurs in Mexico, and the disease severity rate was been increasing for decadesAccording to the World Health Organization. Now, a researcher from Rutgers University has generated data that could help reduce mosquito-borne diseases in the country.
Ubydul HaqueHe is an assistant professor of global health at the Rutgers Global Health Instituteanalyzed data from the Mexican Ministry of Health to identify dengue hotspots. Working with epidemiologists at the University of North Texas and Universidad Autonoma de Nuevo León, the team calculated environmental and socioeconomic risk factors and identified areas where severe outbreaks occurred.
the the findings Published in the journal environmental informatics.
“These maps can help health officials target fogging activities or enhance monitoring,” Haq said. “By knowing where severe dengue occurs most frequently, we can significantly reduce the number of cases.”
Dengue has been reported in 28 of Mexico’s 32 states, and researchers have long known that socioeconomic status and weather influence the number of dengue cases in those states. However, the factors contributing to disease severity have not been studied.
Previous work also failed to account for the geographical distribution of variants or serotypes. There are four serotypes of dengue virus – DENV-1, DENV-2, DENV-3, and DENV-4 – and transmissibility and lethality differ for each.
To fill in these research gaps, Haque analyzed laboratory-confirmed dengue infections from 71,059 individuals in 2,469 Mexican municipalities collected between 2012 and 2020. Samples included serotype classification.
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This data was overlaid with local weather statistics and socioeconomic statistics, such as literacy and access to health services, electricity, and sanitation.
As expected, each degree Celsius increase in temperature was associated with decreased rates of virus incidence—mosquito eggs do not hatch well in high temperatures—while an increase in humidity was associated with an increase in the rate of each virus serotype.
Furthermore, the researchers determined that lower socioeconomic status increases the risk of dengue infection, and that indicators such as access to education, information, and infrastructure are better predictors of dengue distribution.
From this data, the researchers generated the heatMaps highlighting the prevalence and severity of dengue virus. Hot spots have generally been observed in humid coastal regions at lower elevations. Across the country, the most prevalent serotype was DENV-2 and the least prevalent was DENV-4, Haq said.
While efforts are underway to develop vaccines specific for DENV, mosquito control programs such as fogging and drone surveillance remain the most effective means of slowing the spread of the disease. Haq said that data visualization can help health officials plan where to target their activities.
“From our data we know that DENV-2 is more lethal compared to other serotypes,” Haq 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 World Health Organization estimates that dengue fever affects up to 400 million people every year, killing thousands. Haq said that with climate change expected to increase dengue cases in Mexico over the coming decades, constant monitoring of serotype patterns will be necessary to prevent or slow the rate of increase.