[Prevalence of tuberculosis infection in the school age in Guadalajara, Spain]

To estimate the prevalence of tuberculosis infected children in the first grades of Primary Education and to analyse the distribution of infected people among social class groups and other previous circumstances.

Cross-sectional study with diagnostic test application and questionnaire survey, in a representative sample of the school population of the province of Guadalajara, Spain (two stages sampling design). Tuberculin skin tests with 2 I.U. of P.P.D. RT-23 and the Sokal method for lecture were used. For occupational classification and social class definition were used the criteria of the last report of Spanish Epidemiology Society.

A total of 1,093 children (50.8% males) between 6 and 9-year-old were studied. The overall prevalence of infected children was 1.64 (I.C.:1-2.3). The distribution of infection did not show significant differences between urban/rural population, previous disease, family antecedent, social class, dwelling area and occupational activities of parents. The prevalence increased in the older upper school years and among the older children. Prevalence ranged from 0.4% (CI: 0.01-1.3) in the first year to 3.53% (CI: 2.4-4.6) in the last year. Children born in 1988 had a 3.23% prevalence (CI: 1.2-5,1), while those born in 1989; 1990 and 1991 had a prevalence of 0.73 (CI: 0-1.77), 1.88% (CI: 0.2-3.51) and 0.4% (0-1.2), respectively.

Tuberculosis infection is less prevalent at school ages than other areas of Spain. In spite of the increase prevalence per school year, the low frequency and sample size did not allow to test for other associations.