An estimate of the prevalence of hanseniasis by means of investigation into non-specific demand for health services

Abstract

In view of the importance of knowing the prevalence and incidence rates of a disease to learn about its behavior and control at the collective level, a study was undertaken to determine the occurrence of hanseniasis among the clients of health agencies and to expore the use of this methodology for estimating the epidemiologic "iceberg" of the disease, i. e., the total number of cases including those that are not officially reported. The city of Taubaté in the Paraíba Valley, State of S. Paulo, Brazil, was chosen for the study. All clients aged 15 years or older were screened regardless of variables such as sex, age, social condition or marital status. The study was based on what is known about the populational distribution of the disease and the characteristics of health services. In view of the local peculiarities of operationalization (e.g., identity of the different clientelles, availability of offices, hours of greatest flux), the sampling process used was simple randomization. The patients with active disease detected, 40 of the 10,013 persons examined, correspond to a prevalence of 3.99/1000, whith a confidence interval (at the 5% level of reliability) of 3,365 to 4,625/1000, indicating that the minimum estimated increase of prevalence is of the order of 52% and the maximum estimated increase is of the order of 109%. The indeterminate form of the disease predominated among the patients (35.00%), and this predominance was even more explicit when the patients were classified as registered or new cases: in this latter category, the indeterminate form reached 56.53% and its distribution by age range was dose to that observed in the officially recorded data, as verified by comparing observed cases with expected cases calculated from population indicators. As to sex ratio, a was predominance of males was observed.