RESUMO
Resumen El catastro sistemático de contactos con el objetivo de identificar y tratar a aquellos con infección tuberculosa es uno de los pilares establecidos por la OMS en su Estrategia de Fin a la Tuberculosis. El riesgo de infección tuberculosa en contactos escolares, aunque menor que en los domiciliarios, es significativo. Sin embargo, es bajo el cumplimiento del tratamiento preventivo y varios puntos se prestan a discusión, como ser el corte de la prueba tuberculínica a utilizar, el beneficio de iniciar un tratamiento quimioprofiláctico en ausencia de infección demostrada o de realizar estudios en contactos de casos índice no bacilíferos. Este escrito aborda dichos temas y propone, con evidencia actualizada, una modalidad de estudio para contactos en instituciones de enseñanza secundaria. Dicho catastro propone identificar a los infectados utilizando el punto de corte de 5 mm en la prueba de tuberculina, ofreciendo tratamiento preventivo y seguimiento activo solamente a aquellos con una prueba positiva.
Abstract The systematic registry of contacts with the objective of identifying and treating those with tuberculosis infection is one of the pillars established by the WHO in the end Tuberculosis Strategy. The risk of tuberculosis infection in school contacts, although lower than in households, is significant. However, compliance with preventive treatment is low and several points are open to discussion, such as the cutoff of the tuberculin test to be used, the usefulness of starting a chemoprophylactic treatment in the absence of confirmed infection or carrying out studies in contacts of non-bacilliferous index cases. This paper ad dresses these issues and proposes, with updated evidence, a screening modality for contacts in higher education institutions. This screening proposes to identify those infected using the cut-off point of 5 mm in the tuberculin test, offering preventive treatment and active follow-up only to those with a positive test.
RESUMO
Introduction: The risk of tuberculosis infection is associated with close and prolonged contact. Daily contact, poorly ventilated classrooms or delay in diagnosing the index case in a school setting could contribute to contagion. Objective: To know the incidence of latent tuberculosis infection (LTBI) in school contacts comparing two cut-off points of the tuberculin test (PPD, Purified Protein Derivative): ≥ 10mm and ≥ 5mm. To determine the degree of compliance with the performance of control and chemoprophylaxis (ChP) studies. Materials and Methods: We carried out a retrospective analysis of bacillary TB school contacts in teenagers between 12 and 19 years old of the Programmatic Area of the Hospital Parmenio Piñero between February 2016 and December 2017. The evaluation included chest x-ray, lab tests and PPD. We analyzed 2 cut-off points of the PPD: ≥ 10mm and ≥ 5mm, and repeated the test after 3 months in cases with negative results. Primary ChP with isoniazid was indicated for all the contacts, and secondary ChP for those with basal PPD+ or conversion at the third month. We considered ChP compliance in cases where patients followed > 80% of the indicated regime. Results: 331 (89%) of 373 students to be evaluated participated in the study. TB was diagnosed in 4 students (1.2%) through chest x-ray, and they were excluded. Within the remaining 327, the mean age was 15 ± 1.6 years, and 132 (40%) were male. The basal PPD was ≥ 10mm in 20 cases (6.1%), being more frequent in the group of 16-19 years versus the 12-15 years: 10.7% vs. 3.1%; p = 0.004. There wasn't any significant difference regarding sex. 135 contacts (45%) did the second PPD, and 3 conversions were found (2.2%). Primary ChP was indicated for everyone, and secondary ChP for 23 contacts, with 75% and 26% compliance respectively, and without any significant association with age or sex. 4 adverse events were reported (1.2%): polineuritis (n=2), skin allergy and food intolerance. 63 contacts (19.3%) were positive PPD, with PPD ≥ 5mm, being more frequent in males: 26.5% vs. 14.4%, p = 0.006; and in 16-19 vs. 12-15 years: 28.2% vs. 13.2%; p < 0.001. With the second PPD we observed 3 conversions (2.2%). Conclusion: We found 6.1% of LTBI considering a PPD+ ≥ 10mm and 19.3% with PPD ≥ 5mm. Compliance with the second PPD and the secondary ChP scheme was low.