The social and spatial ecology of dengue presence and burden during an outbreak

 EPI Investigators publish paper on the social and spatial ecology of dengue in an Ecuadorean outbreak.

Dengue fever, a mosquito-borne arbovirus, is a major public health concern in Ecuador. In this study, we described the spatial distribution of dengue risk and identified local social-ecological factors associated with a recent outbreak of dengue fever in the city of Guayaquil, Ecuador.

Spatial imaging of a Dengue outbreak
Spatial imaging of a Dengue outbreak.

We examined over 4,000 georeferenced dengue cases and block-level census variables to identify social-ecological risk factors associated with the presence/absence and burden (i.e. number of cases) of dengue in Guayaquil in 2012. Spatial analysis revealed significant hotspots of dengue transmission near the North Central and Southern portions of the city. Significant risk factors for the presence of dengue included poor housing conditions, access to paved roads, and receipt of remittances, while risk factors for increased burden of dengue included poor housing conditions, garbage collection, receipt of remittances, and sharing a property with more than one household.

Two diagrams: one showcases dengue versus increased burden and one showcasing dengue during a 2012 outbreak in Guayaqiol, Ecuador.
Underlying social-ecological factors associated with increased disease risk were different when considering the presence of dengue (A) versus increased burden, or number of cases (B), during a 2012 outbreak in Guayaquil, Ecuador.

The tested variables are spatially diverse within the limits of Guayaquil, thus giving us a better understanding of why some areas within the city are at an elevated risk for severe dengue outbreak. These findings also highlight fundamental differences in the social-ecological drivers of dengue presence versus case burden. Furthermore, our results suggest that vulnerability and risk maps could be developed to inform dengue prevention and control in Ecuador, information that is also relevant for emerging epidemics of chikungunya and Zika viruses.

Written by: Catherine A Lippi