The effects of rainfall and temperature factors on temporal and spatial distribution of malaria in the Anuradhapura District

Abstract

In the Anuradhapura district of Sri Lanka, malaria has been a seriously risky threat over the past decades and malaria epidemic continuous to be a major public healdi problem, particularly in the Eastern and Northern parts of the district. The natural environmental factors that affect die spread of malaria under spatial and temporal conditions are being studied in detail the finding supports to overcome problems associated with the present and future situation in the Anuradhapura district. The aim of this study is to investigate the natural environmental factors related to the occurrence of malaria in the district. Since recent times a gradually decrease in the spatial and temporal pattern of malaria can be detected. Yet, 27 % or 448 of the total number 1,628 of malaria cases found in Sri Lanka in 2005 have been reported from the Anuradhapura district. The peak transmission season of malaria in the district occurs during October to February each year, while highest recorded in January. Seasonal rainfall created in forming breeding grounds for mosquitoes. During the Yala season, there isn't much rain when small tanks dry-up leaving puddles of water here and there forming breeding grounds of mosquitoes. Larger tanks also dry-up to a lesser extent, flow slow forming puddles intermittendy which favour breeding of mosquitoes. Under these favorable conditions, Anopheles mosquitoes emerge from these breeding grounds and may easily suck blood from humans. There is much evidence that temperature and rainfall of Sri Lanka, has changed considered during the last century. The data collected on annual and monthly rainfall as well as on temperature of the Anuradhapura district were collecteted to malaria, incidence to understand if weather has any effects of climatic phenomena on the distribution of malaria both in temporal and spatial perspectives. These results show that monthly rainfall and the occurrence of malaria exhibits a positive relationship and the Maha season is dominated by widespread malaria cases. The temperature between 28.1-28.8 ° C create the most favourable conditions for the occurrence of malaria