Treatment of latent TB infection for close contacts as a complementary TB control strategy in Singapore.

Abstract

To describe our initial experience with treatment of latent tuberculosis infection (LTBI) for close contacts of infectious TB cases in Singapore, an intermediate TB burden country with mass BCG (re)vaccination since the 1950s. Screening of 5699 contacts of 1374 index cases notified in 1998 was carried out at the TB Control Unit. Seventy-five per cent (4239) completed tuberculin skin testing (TST). Fifty-three cases of TB disease were detected (0.9% yield). Twenty-one per cent (895/4239) of the TST-screened contacts were started on LTBI treatment, comprising 92% (810/883) of contacts with TST > or = 15 mm, 5% (64/1195) of those with TST 10-14 mm and 1% (21/2161) of those with TST < 10 mm. The regimen utilized was isoniazid for 6 months in adults and 9 months in children. Eighty-one per cent completed treatment. The incidence of isoniazid-induced hepatitis was 0.45%. Over the ensuing 4 years, one case of active TB was reported among those treated for LTBI, and 10 cases (five without TST readings) were notified among contacts who did not receive treatment. Where good case-finding and treatment of TB disease exist, and where resources permit, LTBI treatment for close contacts is feasible as a complementary TB control strategy in an intermediate TB burden country with a BCG-vaccinated population.