Prevalence of tuberculous infection among students in Naples.

The aim of this study was to estimate the prevalence of tuberculous (TB) infection in Naples, Italy. The target population was defined as pupils aged 6, 9 and 13 yrs, studying in state and private schools in Naples. A stratified cluster sampling design was used. The stratification criteria were: age (6, 9, 13 yrs); type of school (state or private); and district within the town. Prevalence of TB infection was assessed through a tuberculin Tyne test. Some individual risk factors of tuberculous infection were also investigated by means of a simple questionnaire given to pupils' parents. Among observers reproducibility of test reading was also evaluated. An overall prevalence of TB infection of 5.7% (95% confidence interval (95% CI) 4.6-6.8) was observed in the 1,597 sampled subjects. Skin-test positivity was highly variable with age, ranging from 2.8 (95% CI 1.0-4.6) at 6 yrs to 9.4% (95% CI 7.1-11.7) at 13 yrs. In 458 children (28.7%) response was blindly assessed by three independent observers. Reproducibility of tuberculin skin-test reading was good, with an overall kappa value of 0.718. Only parents' drug abuse was found to be significantly associated with infection. This is the first study to evaluate the prevalence of tuberculous infection in Naples.

Asthma and bronchial reactivity: a contribution from multivariate analysis.

This study was performed on 508 young male candidates on the military pilot course of the Air Force Academy. Observations of the following parameters were made: immunoglobulin E (IgE) level, skin sensitivity test (prick test) to most common continuous and seasonal allergens, and results of nonspecific bronchial provocation tests with methacholine. The analysis strategy that has been developed consists of two techniques, "multiple correspondence analysis (MCA)" and "automatic classification". The correlation between the categories of the characters evaluated are: degree of high skin reactivity in relation to high IgE levels, hyperreactivity to low methacholine dose (noticed mainly in subjects allergic to continuous antigens), low degree of skin reactivity (both to continuous and seasonal antigens and found in relation to a low methacholine dose) and medium and low IgE levels. The cluster analysis defined three different classes of subjects: 1) 51.97% of the total observed subjects. 68.82% of those subjects that showed IgE levels above 7300 and a high reactivity to low methacholine dose; 2) 15.94% of subjects with a severe allergy to pollens; and 3) 32.09% of subjects with IgE levels lower than 900, low bronchial reactivity and no allergic component for either seasonal or continuous antigens. The use of multivariate statistical techniques in this field of pathophysiology has allowed a confirmative-explorative study of allergic phenomena in relation to several characters, and the determination of classes of subjects characterized by well-defined categories.