6 - Climate and ENSO Variability Associated with Vector-Borne Diseases in Colombia

Summary

Abstract

Climatic factors are associated with the incidence of diverse vector-borne diseases (VBDs). Colombia, located in tropical South America, witnesses high precipitation rates and temperatures, varying with elevation over the Andes. We show how temperatures are linked to malaria incidence throughout the country, and we compare those results with those obtained via simple mathematical expressions that represent indices associated with malaria transmission as a function of temperature. Interannual climatic variability in tropical South America is strongly associated with El Niño/Southern Oscillation (ENSO). Most of the region, including Colombia, experiences prolonged dry periods and above normal air temperatures during El Niño, and generally opposite conditions during La Niña. Through correlation analysis, we show that during El Niño events there are outbreaks of malaria and dengue fever in Colombia. These outbreaks could be explained in terms of a decrease in precipitation and an increase in air temperature, which favor the ecological, biological, and entomological components of these diseases.

We illustrate the ability to predict malaria cases in Colombia by using an epidemiological model based on the concept of vectorial capacity (see Martens et al. 1997). This transmission potential model is driven with surface air temperatures derived from an atmospheric general circulation model (ECHAM3 model, Max Planck Institute for Meteorology) with a spatial resolution of about 300 km. The malarial model produces peaks in Plasmodium vivax vectorial capacity during El Niño years and an upward trend with time, in agreement with the Colombian malarial historical record.