Revista Brasileira de Epidemiologia
Print version ISSN 1415-790X
CARNEIRO, Mariângela. Epidemiological studies for evaluating the effectiveness of the Chagas' Disease Control Program: a discussion on methods. Rev. bras. epidemiol. [online]. 2002, vol.5, n.1, pp. 129-141. ISSN 1415-790X. http://dx.doi.org/10.1590/S1415-790X2002000100014.
The present paper describes the methodological aspects of different epidemiological designs tested as a model to evaluate the effectiveness of the Chagas' disease control program. The main outcome was the reduction of infection rates by Trypanosam cruzi (etiological agent) measured by serology, in those born after the intervention. The actions of Chagas' disease control programs were based on house spraying with insecticide with the objective of controlling the vector Triatoma infestans (intermediate hosts of T. cruzi). The epidemiological designs used were: 1) Quasi-experimental, conducted in 1987, when an area for comparison was available. The reduction of T. cruzi infection rates in the area where intervention had been carried out for 5 and 10 years was compared with those where there was no intervention (control). The program effectiveness was estimated by comparing the infection rates found in the study with those published by the Chagas' disease serological survey (1975-1980); 2) Panel study, conducted in one area with 13 years of intervention. The objectives were to investigate the T. cruzi infection transmission pattern in a cohort born after the intervention and to verify whether the duration of the program was a determinant factor in inducing change in the incidence. The reduction of T. cruzi infection rates was estimated from data collected on three separate occasions: a national serological survey (1975-80), a quasi-experimental study (1987) and the present investigation (1995); 3) Nested case-control, to evaluate the risk factors of T.cruzi infection, incorporated within a serological survey of school children, which was implemented by the National Health Foundation to evaluate the effectiveness of the Chagas' disease control program. The models tested in different phases of the Chagas' disease control program were adequate for evaluating the effectiveness of the program; methodologies can be extended to other programs; they provide quick answers to the question formulated; they are ethical, since they can be carried out while programs are in progress; they are operationally feasible and might be included by public health institutions at the planning phase of programs.
Keywords : Evaluation of effectiveness; Chagas' disease control program; Quasi-experimental Study; Panel Study; Case-control Study.