The El Niño-Southern Oscillation (ENSO) phenomenon is the main mechanism forcing climate variability in tropical South America in several timescales, impacting the life cycles of disease vectors and host/vector relationships. The dengue is a vector-borne disease with great socioeconomic impact in Colombia, being the arbovirus with the highest mortality. In this analysis, we related the records of Dengue cases registered in Colombia in the period 2007-2017 and the series of sea surface temperature anomalies in the Niño 3.4 region. Furthermore, we studied the effect of the ENSO on precipitation, relative humidity, maximum and minimum air temperature, and wind velocity in Colombia to understand the impact of the ENSO in the dengue incidence. The effect of the ENSO on climatic variables spatially varies. During the warm (cold) phase, i.e., El Niño (La Niña), the maximum and minimum air temperature increase (decrease) throughout the country, but in the Amazonian region, it is less likely to occur. During El Niño the mean rainfall decreases, except in the Orinoquía region where it can increase. In the Pacific and Caribbean regions, rainfall is more likely to decrease in this phase of the ENSO, while surface radiation increases in the Andean region. Wind speed increases in the Andean, Caribbean and Pacific regions, and decreases in the Orinoquía and Amazonian regions. El Niño phase intensifies the incidence rate of Dengue in the Andean, Caribbean, and Pacific regions (correlation between 0.3 and 0.8 with 95% of confidence for lags between 1 and 14 months approximately) and La Niña in the Amazonian and Orinoquía regions (correlation between 0.2 and 0.5 with 95% of confidence for lags between 10 and 20 months approximately). The above should be explained by the decreasing in rainfall and increasing on temperature and wind velocity (less relative humidity) in the Andean, Caribbean and Pacific regions, and the increase in radiation in the Andean region during El Niño. On the other hand, during La Niña, rainfall decreases in the Orinoquía region and decreases on the temperature are unlike in the Amazonian region.

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.