Population mobility and dengue fever transmission in a major city in Southeastern Brazil, 2007-2015

BackgroundAround 14% of world dengue virus (DENV) cases occur in the Americas, the majority of them in Brazil. Although socioeconomic, environmental and behavioral correlates of dengue have been analyzed for different contexts, the role played by population mobility on DENV epidemics, especially at the local level, remains scant. This study assesses whether the daily pattern of population mobility is associated with DENV transmission in Campinas, a Brazilian major city with over 1.2 million inhabitants in Sao Paulo state.\n\nMethodology/Principal FindingsDENV notifications from 2007 to 2015 were geocoded at street level (n=114,884) and combined with sociodemographic and environmental data from the 2010 Population Census. Population mobility was extracted from the Origin-Destination Survey (ODS), carried out in 2011, and daily precipitation was obtained from satellite imagery. Zero-Inflated Negative Binomial (ZINB) regression models controlled by demographic and environmental factors revealed that high population mobility had a substantial positive effect on higher risk for DENV transmission. High income and residence in apartments were found to be protective against the disease, while unpaved streets, number of strategic points (such as scrapyards and tire repair shops), and precipitation were consistently risk factors for DENV infection.\n\nConclusions/SignificanceThe use of fine-scale geographical data can unravel transmission idiosyncrasies not evident from a coarse spatial analysis. Even in a major city like Campinas, the vast majority of population daily mobility occurs at short distances. Based on our results, public policies on DENV transmission control should dedicate special attention to local hubs of population mobility, especially during high transmission weeks and in high dengue incidence areas.\n\nAuthor SummaryCurrently, about half of the world population is at risk of a dengue infection. Numerous studies have addressed the socioeconomic and environmental determinants of the disease. However, little is known about the role played by population mobility on dengue transmission, particularly at the local scale. This study aims at investigating this issue. Our hypothesis was that population movements are a prominent driving force for dengue diffusion locally. We investigated the case of Campinas, a municipality with over 1.2 million inhabitants in Brazil that recorded dengue epidemics in 2007, 2014 and 2015. Our study focused on the years 2007 to 2015, comprising more than 114 thousand cases, geocoded to the household address, and combined with socioeconomic, environmental and daily population mobility data. Our results showed that even controlling for demographic and environmental factors, population mobility was the most important predictor for dengue fever incidence.