title: Focusing tuberculosis contact tracing by smear grading of index cases.
abstract: Several studies have confirmed that the contacts of sputum-smear-positive patients are a high risk group. We made a prospective survey to investigate the contacts of infectious cases of pulmonary tuberculosis in order to evaluate whether different grades of sputum-smear positivity have any consequence in the emergence of new cases. The number of contacts reported by 134 index cases was 609. These included 136 (22%) who had been in close contact to the index case, 69 of them to patients heavily positive by sputum smear. Tracing of 609 contacts over 2 yr revealed four (0.7%) new cases of active tuberculosis. All of them were close contacts, and, moreover, all four (5.8%) belonged to the group of 69 whose index case had a heavily positive sputum smear. This was significantly more than in other contacts, p = 0.0002. To be productive, tracing should be limited to close contacts of heavily smear-positive patients. This seems also to be the group in which chemoprophylaxis could be cost-effectively focused.
authors.affiliation: Department of Diseases of the Chest, Turku University Central Hospital, Preitilä, Finland.
authors.forename: K K
authors.initials: KK
authors.lastname: Liippo
authors.forename: K
authors.initials: K
authors.lastname: Kulmala
authors.forename: E O
authors.initials: EO
authors.lastname: Tala
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D016358:Contact Tracing / Q000706:statistics & numerical data; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D011446:Prospective Studies; D013183:Sputum / Q000382:microbiology*; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000382:microbiology