Bivariate Modelling of Epidemiological Data

Dengue fever and Leptospirosis (rat fever) are two of the most common parasite based diseases in countries with tropical or subtropical climates. Both these diseases can develop into an epidemic situation. Many similar characteristics such as varying with climatic variables and similar clinical manifestation can be seen in dengue and rat fever. The life threatening nature of the two diseases and the spread of the diseases across Sri Lanka, have caused much concern amongst the society. This study focuses on analyzing the counts of dengue fever and Leptospirosis reported. Particular interest is on modeling these counts. Both these diseases vary with climatic factors. Further, the literature has shown the benefits of joint modelling more than one disease outcome that share common risk factors. Thus, this study was carried out with the objective of determining the bivariate distribution of the counts of dengue fever and rat fever, and identifying the determinants with regard to climatic factors. (Rainfall, humidity, temperature and their first two lag values).