Trends of Climatic Factors and Malaria Incidence in the Low,Moderate and High transmissin Zones of Zambia

Abstract

Malaria causes about 1-3 million deaths annually in the world, out of which, more than 90% occur in Africa (World Health Report, 2012). Studies have shown that high incidence of malaria has been exacerbated by the effects of variations in climatic factors (Murray, et al. 2013). Despite the huge burden malaria imposes in Zambia, detailed data of how climate variation has influenced malaria incidence is very limited. A study to examine the influence of climatic factors on malaria incidence in the low, moderate and high malaria transmission zones of Zambia was conducted from June 2014 to January 2016. Multi stage sampling was used to select the districts from the malaria transmission zones. The first stage involved random selection of five provinces which was subsequently followed by random selection of five districts. The third stage involved collection of secondary data from the Ministry of health data base, Health Management Information System (HMIS) and also from the Meteorological Department. Only confirmed malaria cases from 2009 to 2013 were included in the study. Negative Binomial Regression analysis was used to measure the effect that the climatic parameters, have on malaria case counts. A Poisson regression model was used to fit mixed effects model on correlated panel data for count response variable. In this study, a model quasi-Poisson model can also account for dispersion. Results showed that an incidence rate ratio of 1.002 for rainfall which meant that the incidence of confirmed malaria cases in Zambia increased by 0.2 % with every 1 mm increase in rainfall (P = .028). Humidity had an incidence rate ratio of 1.002 which indicated that malaria incidence increased by 2 % for every 10 % increase in humidity (P = .294). The correlation between rainfall and all malaria cases was positive and highly significant (r = 0.197; P = .0006). Discussion-Results from this study found that there is a significant positive association between Rainfall and confirmed malaria cases. Findings of this study also shows that malaria cases increased at the onset of the rains. In March/April, however, the drop in rainfall led to an increase of in malaria cases from March to April. From this study it can be concluded that monthly total rainfall was the only variable influencing incidence of confirmed malaria cases. In conclusion, this study found evidence that rainfall was positively associated with the number of confirmed malaria cases. This study failed to find a significant correlation between relative humidity and malaria incidence in the three malaria epidemiological zones. This can be attributed to the fact that there was paucity of humidity data. Key words: climatic factors, temperature, rainfall, humidity, malaria transmission zones malaria