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[Chemotherapy of the source and the risk of infection in home contacts]
Abstract:
An attack treatment with 3 drugs during 4-6 months and a consolidation treatment with 2 drugs then INH was applied in 595 cases detected between July 1, 1968 and June 30, 1972, i.e. 264 group A (positive), 200 group B (negative cultures) and 131 group C (pleuretics). The contacts had been in close contact with the source for at least three months before establishing the diagnosis; 549 had been vaccinated at birth with BCG and 209 revaccinated; 413 had undergone chemoprophylaxis with INH. The control group comprised 1008 subjects, the mean age of the groups being very close; they were followed up for 2 years and 1 month and 2 years and 7 months. Testing was done every year with 1 u PPD IC 65. The contacts were controlled annually by radiophotography and X-ray and the controls only in case of shifting of the test. Among the contacts there were 44 conversions in the subjects with an initial tuberculin reaction of 0-5 mm and 4 in those with an initial tuberculin reaction of 6-9 mm, representing 15.1% (group A 27.7%, group B 9,8%, group C 10.5%). Three months after the initiation of chemotherapy the proportion of conversions in the three groups (group A 12.3%, group B 5.9%, group C 10.5%) was equal to that of the controls (8.8%). The next year there were 11.2% conversions among the contracts (group A 11.4%, group B 9.6% and C 17.7%) as against 11.9% among the controls. In the first year 8.3% of the contacts contracted tuberculosis (A 15.6%, B 2.4%, C 4.0%) and 0.32% of the controls. The next year 2.8% of the contacts fell ill (A 4.3%, B 2%, C 0%) and 0.5% of the controls. Among group A contacts aged 0 to 6 years there were 31.7% conversions and 30.7% cases of tuberculosis in the first year, and 7.1% and 1.8% respectively in the following year. Group B and C presented 10.9% conversions and 6% cases of disease in the first year, and no case of tuberculosis in the second year. Chemotherapy reduced conversions and sickness in this group three months after the diagnosis was established.