Determinants of dengue transmission during epidemic and inter-epidemic periods in two Colombian cities.

摘要

Dengue fever is an urban disease that has a complex epidemiology consisting of alternating periods of intense epidemics and persistence in endemic locations. No studies have compared the patterns of geographic variation and determinants of dengue transmission in neighborhoods during epidemic and non-epidemic periods. Colombia's individual-based epidemiological surveillance system provides a unique opportunity to study this topic. The goal of this study was to better understand dengue epidemiology in two of the highest dengue fever reporting Colombian cities that vary in climate, Armenia (elevation 1320-1580 m, 21-23 C) and Barranquilla (elevation 5-134m . 27-30 C). We used a novel ecological approach, Levin's niche breadth, to define epidemic and inter-epidemic periods in each city. Regression tree models were built with the following outcome variables for each neighborhood: total number of dengue cases reported during the study period and proportion of dengue cases that occur during inter-epidemic periods. The explanatory variables used were elevation, house count (in lieu of population), housing density, and the Colombian socioeconomic class (SEC) indicator. House count was consistently found to be the main determinant of the total number of reported dengue cases in neighborhoods in both cities. The proportion models identified different determinants of persistent dengue virus transmission in the two cities. Lower elevation was the main driver of persistence in Armenia while lower SEC was the main driver in Barranquilla. These findings suggest that although the overall number of dengue cases depend on the impact of population (as represented by house count) on viral introduction, factors that influence the reproductive rate have a larger influence on transmission during inter-epidemic periods. The persistence determinants identified in this study could potentially help vector control programs to identify key areas to focus disease control efforts.