Search

Problems referring to the School curriculum of graduates in Public Health are discussed, and a programme for a one semester course is presented, in order to shorten this preparation.

The increasing endemicity of tuberculosis resulting from causes such as immigration, poverty, a declining public health infrastructure and co-infection by HIV/Mycobacterium tuberculosis, is leading to a change in tuberculosis control programmes. One of the main reasons for the resurgence of tuberculosis is HIV infection--the risk of tuberculosis is greater in HIV patients than in the majority of the population as can be seen from numerous research projects. The need for systematic testing for HIV infection in all tuberculosis patients by undertaking confidential HIV tests on admission to a tuberculosis programme is brought out. This measure would increase the number of cases diagnosed and provide data for better surveillance of the co-infection.

The applicability of tuberculin test in children under five years of age, BCG-vaccinated during their first year of life, is a controversial matter. With a view to clarifying the subject the predictive positive value of the test in a region of high BCG coverage and low prevalence of tuberculous infection was analysed. From the proportion of strong reactors among infants and school-age children, vaccinated and not unvaccinated, the declining rate of BCG induced allergy and the increment rate of naturally acquired tuberculin sensitivity between the first and the seventh years of life were calculated. Those calculations allowed for the estimation of the respective values for the intermediate ages. The numbers of false positives to be expected were calculated by difference. Knowing the sensibility and the specificity (1 - FP) of the test, the BCG coverage and the prevalence of infection, the predictive values for tuberculous infection were: 1.52%, 4.22%, 8.26%, 14.86% and 23.00%, respectively from the first to the fifth years of life. Under these conditions, the probability of a strong reaction being provoked by BCG is very high, decreasing the applicability of the test both in clinics and epidemiology.

The revaccination of schoolchildren can restore the residual allergy induced by vaccination in the first years of life but can not modify the allergy resulting from a natural infection. So revaccination in this population should indicate the group infected by the Koch bacilli. To assess the applicability of these assumptions in estimating the risk of tuberculosis infection in regions with high BCG coverage a study was undertaken on schoolchildren between 6 and 9 years of age who were attending the municipal schools in the east zone of S. Paulo City, in the course of the first semester of 1988. Of 11,455 who were vaccinated only 7,470 were tested with PPD, revaccinated and retested ten weeks later; 3,314 of these were vaccinated in the first trimester of life with a half dose and 4,156 received a full dose at later ages (75% during the first year, 20% during the second and 5% during the third). In comparing the results pre and post vaccination by correlation table, the calculation of infection was made according to the criteria of the original method and to the modifications made by the authors under separate cover for those vaccinated in the first trimester and those vaccinated later. The risk of infection was 0.35% and 0.37%, respectively, for the original model and 0.45% and 0.49% for the modified model. The referential was 0.55%. The difference between model and age or with the referential was not significant (p > 0.005). Data suggest that the method is applicable to estimate the risk of tuberculosis infection in schoolchildren vaccinated with a full dose of BCG during the first year of life.

The successful application of Bhattacharya's method (decomposition of frequency distribution into normal components by a graphic method) in the analysis of the results of tuberculin test performed on a population sensitized by "anonymous" strains of mycobacteria, suggested the possibility of its application to two samples of BCG vaccinated school-children, living in the city of S. Paulo (Brazil). One of the sample groups, vaccinated between the second and seventh years of life, was surveyed in 1982 and the other, vaccinated during the first year of life, was surveyed in 1988. In both populations it was possible to characterize the normal component corresponding to children infected by tuberculous bacilli and to quantify them. In the first one, the average size of the reactions was 17.40 mm, the standard deviation 3.72 mm and the proportion of infected children 7.71%, against 4.85% in the unvaccinated control group; otherwise, in the population surveyed in 1988, the average size was 17.00 mm, the standard deviation 4.67 mm and the proportion of infected children amounted to 4.14% against 4.48% in the control group. It is concluded that the method permits the estimation of the prevalence of tuberculosis infection among BCG-vaccinated school-children, provided that the vaccine has been given during the first year of life.