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Impact of Climate Change on Malaria Distribution in Thailand

By Salsabila Lohya and Uma Langkulsen


Background:
 Climate change remains a global problem that poses wider economic, social and environmental effects. Global temperatures are rising and are likely to increase every year. Because it is difficult to avoid, the rate of climate change may even be intensified by a quarter. Effects of climate change are being witnessed, both directly and indirectly, and with varying levels of severity. Climate change has proved to be taking its toll on malaria distribution. Thailand is not spared, as malaria is a significant health problem in the country especially in the provinces along the borders. Currently, there is a downward trend in the reported number of malaria cases, but the distribution of the disease in new areas and infections in old areas are still major problems for the country.   

Objective: The main purpose of this study was to analyze the relationship between climatic factors and the distribution of malaria in Thailand.  

Methodology: Analysis was conducted using data on monthly and yearly climatic factors as well as monthly and yearly malaria cases reported in Thailand during the period 2004 - 2013. The study population comprised 76 provinces of Thailand. All the data were entered and analyzed using SPSS - 17 database program. Simple regression, multiple regression and Spearman correlation analyses were used to assess the association between temperature, rainfall, relative humidity and morbidity rate of malaria.  

Results:
 Climate change affects malaria distribution as a result of three climatic factors. These three climatic factors (namely temperature, rainfall, and relative humidity) are all correlated amongst themselves and they each have independent associations with malaria morbidity rate. However, temperature has the greatest impact on malaria morbidity. Temperature, rainfall, relative humidity all had relationships with malaria morbidity rate in the same direction with positive correlation coefficients [0.539; 95%CI (0.339, 0.739)], [0.009; 95%CI (0.005, 0.013)], [0.110; 95%CI (0.045, 0.175)] respectively. After adjusting f or other variables, only temperature was associated with malaria morbidity rate with a statistically significant correlation coefficient [0.416; 95%CI (0.188, 0.643)].  

Conclusion: There was a significant association observed between climate change and malaria distribution in the last decade. In the future, multi - disciplinary research involving researchers from fields such as public health, parasitology, epidemiology, entomology, botany, agriculture and climatology is necessary to evaluate and investigate the real effect of climatic factors on malaria distribution.