Association between dengue incidence and climatic factors

OBJECTIVE: To describe the occurrence of autochthonous dengue cases according to sex, age, suspected infection site and its relation with climatic variables. METHODS: Autochthonous dengue cases reported in S?o Sebasti?o, Southern Brazil, from 2001 to 2002 and confirmed in laboratory were studied. Larval density was verified by three indexes: building, recipients and Breteau. The relationship between rainfall, temperature and number of cases was analyzed through Spearman's correlation using time lag. RESULTS: The annual incidence coefficients for 2001 and 2002 were 80.3 and 211.1 per 10,000 inhabitants, respectively. Most dengue cases (n=1,091; 65%) were reported in the district's central area. Females (n=969; 60%) and the age groups 20 to 29 and 30 to 39 years old of both sexes were mostly affected. Significant associations were not observed between climatic variables and the number of dengue cases in the first month; however, this association became evident in the second month throughout the fourth month. CONCLUSIONS: The association between the number of dengue cases and abiotic factors identified the time lag in which rain and temperature favored the occurrence of new cases. These aspects, associated to tourist vulnerability in the coastal area, promoted conditions for dengue occurrence. The urbanization without sanitary infrastructure possibly affected mosquito density and dengue incidence. Such factors may have contributed to mosquito dispersion and dissemination of different dengue serotypes.