CORRELATION OF CLIMATE VARIABILITY AND MALARIA A RETROSPECTIVE COMPARATIVE STUDY, SOUTHWEST ETHIOPIA

Abstract

BACKGROUND: Climatic variables can determine malaria transmission dynamics. To see thecorrelation between malaria occurrence and climatic variables, records of malaria episodes over eightyears period were analyzed incorporating climatic variables around Gilgel-Gibe Hydroelectric Dam andcontrol sites.METHODS: Records of 99,206 confirmed malaria episodes registered between 2003 and 2011 wereanalyzed along with local meteorological data of the same duration. Data were analyzed with SPSSstatistical software version 20 for Windows. Spearman correlation coefficient was estimated as a measureof the correlation.RESULTS: The major peaks of malaria prevalence were observed following the peaks of rainfall in theGilgel-Gibe Hydroelectric Dam site. In the control site, the peaks of malaria in some years coincided withthe peaks of rainfall, and the pattern of rainfall was relatively less fluctuating. Mean rainfall wasnegatively correlated with number of malaria cases at lags of 0 and 1 month, but positively correlated atlags of 2 to 4 months. Mean relative humidity showed significant positive correlations at lags of 3 to 4months. Monthly mean maximum and minimum temperatures weakly correlated at lags of 0 to 4 months.CONCLUSIONS: Correlations of malaria and climate variables were different for the two sites; inGilgel-Gibe, rainfall and relative humidity showed positive correlations. However, in the control site, thecorrelation of weather variables and malaria episodes were insignificant. Exploration of additionalfactors such as vegetation index and physico-chemical nature of mosquito breeding site may improveunderstanding of determinants of malaria dynamics in the area.