Epidemiology and Infection

Original Papers

Outbreaks and control of infection

Population-based contact investigation of a cluster of tuberculosis cases in a small village

J. CASTILLAa1a2 c1, R. PALMERAa3, A. NAVASCUÉSa4, M. ABETIa5, A. GUILLERMOa5, F. IRISARRIa1a2, M. S. JIMÉNEZa6, M. GARCÍA CENOZa1a2 and A. BARRICARTEa1a2

a1 Insituto de Salud Pública de Navarra, Pamplona, Spain

a2 CIBER de Epidemiología y Salud Pública (CIBERESP), Spain

a3 Programa de Epidemiología Aplicada de Campo, Centro Nacional de Epidemiología, Instituto de Salud Carlos III, Madrid, Spain

a4 Servicio de Microbiología, Hospital de Navarra, Pamplona, Spain

a5 Centro de Atención Primaria, Navarra, Spain

a6 Centro Nacional de Microbiología, Majadahonda, Madrid, Spain

SUMMARY

A cluster of five cases of tuberculosis (TB) in persons aged 19–23 years who were not close contacts was detected in a small village in Spain in 2006. All culture isolates had the same chromosomal-DNA restriction pattern. Contact investigations of family members, friends, workmates and schoolmates were complemented with tuberculin screening offered to the resident population born between 1976 and 1995. Expanded contact tracing detected two new cases of TB, 27 tuberculin conversions and an excess of latent tuberculosis infections (LTI) in persons born between 1978 and 1990. The contacts of two cases had a significantly elevated prevalence of LTI. Two secondary cases of TB, 33·3% of those diagnosed with LTI and 47·8% of the converters were unaware of any contact with the TB cases, but had frequented some of the same bars. This study suggests that a considerable percentage of the episodes of TB transmission in young people may escape detection in conventional contact studies.

(Accepted January 20 2009)

(Online publication March 10 2009)

Correspondence:

c1 Author for correspondence: Dr J. Castilla, Instituto de Salud Pública de Navarra. Leyre 15, 31003 Pamplona, Navarra, Spain. (Email: jcastilc@navarra.es)

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