Masi E. Intervention analysis in time series of dengue and leptospirosis of the city of São Paulo: political, administrative, technical and environmental factor impact [Thesis]. São Paulo: "Faculdade de Medicina, Universidade de São Paulo"; 2014.Dengue and leptospirosis are among the major zoonosis of occurrence in the world; the first because of the epidemic potential and the second due to high lethality. In São Paulo, dozens of leptospirosis cases and hundreds of dengue fever cases are registered annually, being some of the most important events to the municipal public health surveillance system. To understand the effect of climatic conditions and the impact of measures of prevention and control over the transmission of such diseases in the time context, two time series approaches were used: 1) Transfer Functions, with ARIMA error structure (ARIMAX), modeled by Box-Jenkins methods and 2) Additive Generalized Models (GAM) of Poisson regressions, with time structure given by Polynomial Distributed Lags (PDL). The most important climatic factors that increased the number of cases of dengue fever in the city of São Paulo were the elevation in air temperature, precipitation, vector density and the number of imported cases, which increased after carnival holiday (an important calendar event). The arrival of cold fronts from the south (air temperature <16°C) and extreme precipitations (<7mm or >70mm) are factors that decrease the number of new dengue cases. The public health preventive interventions adopted by the municipality were effective in diminishing the dengue occurrence. The most important factors that increased the number of leptospirosis cases in São Paulo were elevation in maximum air temperature and precipitation. Largest amount of hours of sunshine decreased the number of new cases of leptospirosis. The methods used were adequate to the study objectives, the relations among the interest lagged factors and dengue and leptospirosis transmission in the city of São Paulo were satisfactorily modeled. Such techniques also seem appropriate as tools to be incorporated into the municipal health surveillance system, allowing the prediction of the number of future disease cases and understanding temporal relations between diseases and their determinants and conditioning factors.