The Brazilian program for schistosomiasis control, 1975-1979.

Schistosomiasis mansoni is increasingly epidemic and is one of the three worst threats to public health in Brazil. The Brazilian schistosomiasis control program aims to control the disease and, eventually, its transmission. It uses a new ecological approach, trying to find a breaking point in the chain of transmission. There are some known vulnerable links, but the breaking point may be at a higher level in more stable links than in less stable ones. An adaptable methodology, taking into account local peculiarities, is actively developed for each settlement. Chemotherapy may play an important role in screening the input links with low breaking point. Adaptable methodology leads to the identification of ecosystems in which costly and time-consuming sanitary measures may be postponed as far as schistosomiasis control is concerned. The program was tested during 4 years (1975 - 1979) in the State of Rio Grande do Norte, Brazil, and results surpassed expectation; however, appraisal of a schistosomiasis control program takes not years but decades. The available results indicate that schistosomiasis control should be given long-term evaluation. Research on epidemiological systems analysis, identification of variables, and quantification of probabilities are pressing needs. The lack of sound and comprehensive knowledge of the transmission ecosystem imposes the use of an adaptable methodology which will not produce merely a series of unfruitful control attempts if the assay conditions are adequately identified and results are properly analyzed in a continuous, active manner.