UTILITY OF TUBERCULIN AND ANERGY SKIN TESTING IN PREDICTING TUBERCULOSIS INFECTION IN HUMAN IMMUNODEFICIENCY VIRUS-INFECTED PERSONS IN THAILAND

SETTING: Chiang Rai, the northernmost province of Thailand, where exte nsive human immunodeficiency virus (HIV) transmission has resulted in a rapid increase in tuberculosis. OBJECTIVE: To assess the utility of tuberculin and anergy skin testing to identify latent Mycobacterium tu berculosis infection in HIV-infected persons. DESIGN: A cross-sectiona l study and analysis were conducted to examine reactivity to tuberculi n and two control antigens (mumps and candida) in HIV-negative and HIV -positive blood donors and female sex workers. RESULTS: HIV-positive p ersons had markedly decreased tuberculin reactivity; 14%, 19%, and 40% had an induration of greater than or equal to 10 mm, greater than or equal to 5 mm, greater than or equal to 2 mm, respectively, while 51% of 525 HIV-negative persons had an induration of greater than or equal to 10 mm (P < 0.001). Mumps and candida positivity (reactions of grea ter than or equal to 3 mm) were found in 94% and 78% of HIV-negative p ersons compared with 72% and 61% of HIV-positive persons, respectively (P< 0.001). Although HIV-positive persons had markedly less tuberculi n reactivity even at higher CD4 + cell counts (>400 cells/mu L), react ivity to mumps and candida was present in more than half of HIV-positi ve persons with low CD4 + cell counts (less than or equal to 200 cells /mu L). Reaction to control antigens did not predict tuberculin reacti vity. CONCLUSION: In this setting, tuberculid and anergy skin testing have a low predictive value in detecting M. tuberculosis infection in HIV-infected persons, and therefore such testing has a limited role in identifying HN-infected persons who may benefit from tuberculosis pre ventive therapy programs.