Spatial diffusion of the 2015-2016 Zika, dengue and chikungunya epidemics in Rio de Janeiro Municipality, Brazil

Abstract

Different countries, especially Brazil, that have faced recurrent dengue epidemics for decades and chikungunya epidemics since 2014, have had to restructure their health services to combat a triple epidemic of arboviruses - Zika, dengue and Chikungunya - transmitted by the same vector, mainly Aedes aegypti, in 2015-2016. Several efforts have been made to better understand these three arboviruses. Spatial analysis plays an important role in the knowledge of disease dynamics. The knowledge of the patterns of spatial diffusion of these three arboviruses during an epidemic can contribute to the planning of surveillance actions and control of these diseases. This study aimed to identify the spatial diffusion processes of these viruses in the context of the triple epidemic in 2015-2016 in Rio de Janeiro, Brazil. Two study designs were used: cross-sectional and ecological. Sequential Kernel maps, nearest-neighbour ratios calculated cumulatively over time, Moran global autocorrelation correlograms, and local autocorrelation changes over time were used to identify spatial diffusion patterns. The results suggested an expansion diffusion pattern for the three arboviruses during 2015-2016 in Rio de Janeiro. These findings can be considered for more effective control measures and for new studies on the dynamics of these three arboviruses.

Keywords: Chikungunya virus; Zika virus; dengue virus; spatio temporal analysis.

Fig. 1.

Maps of Brazil, and the State and Municipality of Rio de Janeiro, with divisions by planning regions and neighbourhoods. (a) Map of Brazil with divisions by State. The State of Rio de Janeiro is indicated in grey. (b) Map of the State of Rio de Janeiro with divisions by the municipality. The municipality of Rio de Janeiro is shown in grey. (c) Municipality of Rio de Janeiro with divisions by planning regions (colours) and by neighbourhoods (codes).

Fig. 2.

Zika, chikungunya and dengue epidemic curves for the Rio de Janeiro municipality in 2015 and 2016.

Fig. 3.

Georeferences of registered cases of ZIKV, CHIKV and DENV infections in Rio de Janeiro.

Fig. 4.

Sequential kernel maps of Zika cases from epidemiologic weeks 40 of 2015 to 39 of 2016.

Fig. 5.

Sequential kernel maps of Chikungunya cases from epidemiologic weeks 44 of 2015 to 51 of 2016.

Fig. 6.

Sequential kernel maps for dengue for epidemiological weeks 01 of 2015 to 40 of 2015.

Fig. 7.

Sequential kernel maps for dengue for epidemiological weeks 41 of 2015 to 40 of 2016.

Fig. 8.

Best fit resulting curves generated by the nearest-neighbour variation over time for Zika, chikungunya and dengue.

Fig. 9.

Correlograms of the global Moran's I for the incidence rates of Zika, chikungunya and dengue in Rio de Janeiro, 2015–2016.