Impact of El Niño-Southern Oscillation and local climate in Dengue in
Colombia at different spatiotemporal scales
Abstract
Dengue virus (DENV) is an endemic disease in the hot and humid low-lands
of Colombia. We characterize diverse temporal and spatial patterns of
monthly series of dengue incidence in diverse regions of Colombia during
the period 2007-2017 at different spatial scales, and their association
with indices of El Niño/Southern Oscillation (ENSO) and local climatic
variables. For estimation purposes, we use linear analysis tools
including lagged cross-correlations (Pearson test), cross wavelet
analysis (wavelet cross spectrum, and wavelet coherence), as well as a
novel nonlinear causality method, PCMCI, that allows identifying common
causal drivers and links among high dimensional simultaneous and
time-lagged variables. Our results evidence the strong association of
DENV cases in Colombia with ENSO indices and with local temperature and
rainfall data. El Niño (La Niña) phenomenon is related to the
intensification (weakening) of dengue cases at the national level and in
most regions and departments, with maximum correlations occurring at
shorter time lags in the Pacific region, closer to the Pacific Ocean.
This association is mainly explained by the ENSO-driven increase in
temperature and decrease in rainfall, especially in the Andes and
Pacific regions. The influence of ENSO is not stationary (there is a
reduction of DENV cases since 2005) and local climate variables vary in
space and time, and thus it is not easy to extrapolate results from one
site to another. The association between DENV and ENSO varies at
national and regional scales when data are disaggregated by seasons,
being stronger in DJF and weaker in SON. Specific regions (Pacific and
Andes) control the overall relationship between dengue dynamics and ENSO
at national scale, and the departments of Antioquia and Valle del Cauca
determine those of the Andes and Pacific regions, respectively. Cross
wavelet analysis indicates that the ENSO-DENV relation in Colombia
exhibits a strong coherence in the 12 to16-months frequency band, which
denotes the frequency locking between the annual cycle and the
interannual (ENSO) timescales. Results of nonlinear causality metrics
reveal the complex concomitant effects of ENSO and local climate
variables (Fig. 1), offering new insights to develop early warning
systems for DENV in Colombia.