Effect of climate change, connectivity, and socioeconomic factors on the expansion of the dengue virus transmission zone in 21st century Brazil: an ecological modelling study
Lee, SA; Economou, T; Barcellos, C; et al.Catão, R; Carvalho, MS; Lowe, R
Date: 20 April 2021
Journal
The Lancet Planetary Health
Publisher
Elsevier
Publisher DOI
Abstract
Background Globally, incidence of dengue fever has increased more than 30-times in the past 50 years, with outbreaks
becoming frequent in tropical and subtropical countries. This rapid emergence has been attributed to increased
urbanisation, globalisation, international mobility, and climate change. Brazil is endemic to all four ...
Background Globally, incidence of dengue fever has increased more than 30-times in the past 50 years, with outbreaks
becoming frequent in tropical and subtropical countries. This rapid emergence has been attributed to increased
urbanisation, globalisation, international mobility, and climate change. Brazil is endemic to all four dengue virus
serotypes with outbreaks occurring in every region of the country. Previous studies identified geographical barriers to
dengue diffusion, with some regions of Brazil being relatively protected from outbreaks. These regions included
areas in the south of the country where seasonal temperatures were too cold for vectors to efficiently transmit the
virus, regions of the western Amazon that were isolated from infectious hosts and vectors, and mountainous regions
of southeast Brazil.
Methods In this ecological modelling study, we used a Bayesian spatiotemporal model to understand the effect of
climate variation, connectivity between cities, and socioeconomic factors, such as urbanisation, on the expansion of
the permanent dengue virus transmission zone in Brazil. We obtained monthly dengue fever case data from
5560 municipalities in Brazil for 2001–19 from the Notifiable Diseases Information System (SINAN) surveillance
system. The model was fitted to an outbreak indicator defined as exceeding 300 cases per 100 000 inhabitants per
year. Fixed effects included climate suitability and hydrometeorological variables obtained from the Climate Research
Unit (University of East Anglia, Norwich, UK), the level of influence of a city from the Brazilian Regiōes de Influência
das Cidades study, and socioeconomic factors, such as urbanisation, from census data. Spatiotemporal random
effects were included to account for unobserved heterogeneity, spatial autocorrelation, and temporal trends.
Findings Data from the past 10 years showed that pre-identified geographical barriers to dengue virus transmission
are being eroded or destroyed completely. The emergence of dengue fever outbreaks in south Brazil coincided with
an increase in the number of months per year with temperatures suitable for transmission.
Interpretation Understanding the factors that lead to the erosion of barriers to dengue virus transmission will help
identify regions at risk of future outbreaks, and improve public health preparedness to emerging and re-emerging
diseases.
Mathematics and Statistics
Faculty of Environment, Science and Economy
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