Determinants of dengue 2 infection among residents of Charters Towers, Queensland, Australia

Dengue fever is caused by one of the four serotypes of the dengue virus and is transmitted by the urban mosquito Aedes aegypti. In 1993, the city of C harters Towers in the tropical north of Australia experienced an epidemic c aused by the dengue 2 virus. A cross-sectional sample of 1,000 people was a ssessed for determinants of recent symptomatic dengue infection. After excl usion of people with prior exposure to dengue 2, a study group of 797 perso ns, including 196 patients with recent infection, were evaluated. Stepwise logistic regression analysis identified four determinants of infection: the presence of a case of dengue fever within two residential blocks (odds rat io (OR) = 3.61, 95% confidence interval (CI) 2.56-5.10), house screening (O R = 0.60, 95% CI 0.40-0.89), the presence of a water tank within two reside ntial blocks (OR = 1.51, 95% CI 1.02-2.22), and the use of knockdown insect icide (OR = 1.75, 95% CI 1.22-2.51). Classification and Regression Tree ana lysis identified a group of 152 individuals in whom the prevalence of dengu e infection was 50%. These people lived within two blocks of a suspected de ngue fever case, did not have house screening, and used knockdown sprays. I f dengue had not occurred within two residential blocks, there were no addi tional factors that significantly influenced the prevalence of dengue fever , Control of dengue epidemics should involve attempts to geographically con tain the spread of infection, use of house screening, and the removal of mo squito breeding sites such as water tanks.