PREDICTING HIGH-RISK YEARS FOR MALARIA IN COLOMBIA USING PARAMETERS OF EL-NINO SOUTHERN OSCILLATION

The interannual variation in malaria cases in Colombia between 1960 an d 1992 shows a close association with a periodic climatic phenomenon k nown as El Nino Southern Oscillation (ENSO). Compared with other years , malaria cases increased by 17.3% during a Nino year and by 35.1% in the post-Nino year. The annual total number of malaria cases is also s trongly correlated (r = 0.62, P < 0.001) with sea surface temperature (SST) anomalies in the eastern equatorial Pacific, a principal paramet er of ENSO. The strong relation between malaria and ENSO in Colombia c an be used to predict high and low-risk years for malaria with suffici ent time to mobilize resources to reduce the impact of epidemics. In v iew of the current El Nino conditions, we anticipate an increase in ma laria cases in Colombia in 1998. Further studies to elucidate the mech anisms which underlie the association are required. As Colombia has a wide range of climatic conditions, regional studies relating climate a nd vector ecology to malaria incidence may further improve an ENDO-bas ed early warning system. Predicting malaria risk associated with ENSO and related climate variables may also serve as a short-term analogue for predicting longer-term effects posed by global climate change.