Impact of Climatic Factors on Dengue Incidences in Eastern Province, Sri Lanka

Introduction: Health sector is one of the most important sectors of any country. Many aspects such as diseases, health practices, and institutions are associated with health. Among different infectious diseases, dengue has become a major health issue for human in most tropical and subtropical regions. It is a viral disease originated and spread from mosquito and it is in several forms. Since, this seriously affects human life, taking necessary measures, including policies, rules, regulation and best practices to bring this menace into a minimum level, is essential. Such actions require proper background about the disease including factors that this disease depends on. Several factors may be associated with dengue fever and climatic variables take a greater place. Effect of these variables may vary from area to area.

Aims: This study aimed to investigate the impact of climatic variables for progression of dengue disease in the Eastern Province of Sri Lanka, which is consisted of three districts: Batticaloa; Trincomalee and Ampara.

Study Design: Number of dengue incidences and climatic variables such as rainfall, temperature, number of rainy days, day time humidity, night-time humidity, number of sunny days, and UV Index were obtained for each month in the period from 2009 to 2017 from Meteorology Department and statistical abstracts of Sri Lanka. Analysis was carried out by using the statistical techniques: correlation analysis; regression analysis; principle component analysis and a graphical technique, contour maps.

Results: Only a few climatic factors affect dengue incidences in these three districts. However, no any regular pattern could be observed. Impact of each climatic factor varies from district to district. In Batticaloa district, a number of rainy days and day time humidity affect dengue incidences negatively and positively respectively meanwhile wind speed positively affects dengue incidences in Ampara district. No any climatic variables in Trincomalee district show a relationship with dengue incidences in the district. In general, moderate humidity creates a favourable situation for the spread of dengue disease irrespective of districts. Heavy rainfall does not show a relation with dengue incidences as people believe.

Conclusion: It is difficult to investigate the impact of each climatic factor alone on dengue incidences because there are inter correlated. Number of dengue incidences may depend on many other variables such as population density, geographical location, health practices, personal health status, knowledge, policies of different institutes and organizations. It is essential to incorporate these sorts of variables also to have a proper understanding of the dengue disease and its spread.