Tuberculosis latente: diagnóstico y tratamiento actual

Abstract

Latent tuberculosis infection (LT) affects 23% of the population and constitutes a reservoir of tuberculosis (TB) as 10% progresses to TB. LT is recognized by tests such as tuberculin (PPD or TST) and Interferon gamma release assays (IGRAs). The sensitivity of IGRAs (Quantiferon TB Gold plus version) is 94% and PPD 77%. The specificity of Quantiferon TB Gold Plus is 97% and PPD 68%. The predictive value of progression to active TB of these tests is low (PPD: 1.5%, IGRAs: 2.7%) but improves in people at high risk of contracting TB (PPD: 2.4%, IGRAs: 6.8%). People with negative tests who subsequently turn around (positive) have a higher risk of progression to active TB. These tests are useful in the follow-up of intra-household contacts, foreigners from countries with high rates of TB, immunosuppressed, chronic kidney disease, diabetes, silicosis and pulmonary sequelae of untreated TB. In LT therapy, self-administered isoniazid (H) is used for periods from 6 to 12 months with protective efficacy of 60% and risk of liver toxicity of 2%, but with low adherence (50-70%). The association of H with rifapentine in a single weekly dose for 12 weeks has efficacy of 81%, adherence of 82% and low liver toxicity (0.4%). New LT biomarkers and vaccines that improve immunity in LT are under study. Treatment of LT may reduce the incidence of TB in the long term.