Patients with pulmonary tuberculosis (TB) can infect people in their environment but children and adolescents are rarely contagious. A recent case of an adolescent girl in Lausanne, however, proved to be infectious and required extensive contact tracing.
The source case was a 15-years-old adolescent girl of African origin. Upon her arrival in Switzerland in 1994 the tuberculin skin test was 14 mm. The patient did not receive preventive treatment. She developed smear-positive pulmonary tuberculosis in May 1999. Contact tracing identified contacts in the surrounding population. The contact persons were divided into 3 groups according to their proximity. The first group consisted of close family and friends, the second of classmates and teachers and the third of more distant contacts. Costs were also evaluated.
Of the 53 people examined, 24 (45%) were infected and required treatment. Eight out of 9 cases (88%) were infected in the first group (including another case of culture-positive pulmonary tuberculosis). Fourteen out of 33 cases (42%) in the second group and 2 of 11 (18%) to the third group. Passing from one proximity group to the next decreased the relative risk of infection 4 fold. The costs of contact tracing and treatment are estimated at over CHF 24,000.
(1) Pulmonary TB can be contagious even in adolescents. (2) Subdividing contacts into proximity groups allows for better targeting of the people to be screened. (3) Contact tracing and the high costs involved could have been avoided if the patient had received preventive chemotherapy upon her arrival in Switzerland.