[New blood tests for diagnosis of infection with Mycobacterium tuberculosis].

INTRODUCTION

A major challenge in tuberculosis (TB) control is the diagnosis and the treatment of latent tuberculosis infection.

STATE OF THE ART: At the time, the diagnosis is based on tuberculin skin test (TST). TST is not specific, has poor sensitivity and is not easy to perform.

PERSPECTIVES: Two interferon-based tests for the diagnosis of tuberculosis have just been licensed. These tests have some advantages on TST. They require only a blood sample and their results are not dependent on the examinator. Their specificity is higher than TST because they don't cross-react with BCG vaccination and with most of the environmental Mycobacterium species. Their sensitivity is higher for the diagnosis of active tuberculosis too. For latent tuberculosis, the interferon-gamma assays show a better correlation with the exposure to Mycobacterium tuberculosis than TST. The ability to detect TB of the two tests seem to be reduced in immunocompromised patients, specially in medically ones.

CONCLUSIONS

Interferon-gamma assays seems to be useful tools in TB detection, but these good results have to be confirmed in larger studies with unselected patients.