Longitudinal studies on human Chagas disease in Bambui, Minas Gerais, Brazil

The region of Bambui, in Minas Gerais, Brazil, has been followed since 1944 by the Oswaldo Cruz Foundatrion, in terms of morbidity, epidemiology and control of human Chagas Disease (HCD). The highly endemic period was between 1940 and 1955, when an elevated triatomine density resulted in more than 300 acute cases. Since 1956, regular control activities against domestic triatomines were implemented, reducing drastically the incidence of HCD. The regular clinical follow up of acute cases permited to study the natural history of the disease, revealing several factors risks such as gender, severity of acute phase and clinical findings such as cardiac failure, complexes arrhythmias and advanced AV or intra ventricular blocks. For acute period, the more severe prognosis factors were: low age, black skin color, cardiac failure, meningoencephalitis and QRS low voltage in EKG. At long term, a significant correlation between the severity of the acute onset with the development of digestive and cardiac involvement was found. This point remarks the importance of vector control in the area, since low indoors triatomine density was correlated with benign acute phase and minor proportion of acute disease in lower age groups. The reduction of re-infection could also be responsible for a more benign evolution in the chronic stage. The study also showed tilt: initerrupt evolution of digestive and cardiac chronic forms, even SO years after the acute phase. In terms of mortality, HCD has been the most important cause of death in this group, specially the advanced cardiac forms.