Human immunodeficiency virus associated tuberculosis more often due to recent infection than reactivation of latent infection [Review article]

BACKGROUND: It is unclear whether human immunodeficiency virus (HIV) increases the risk of tuberculosis (TB) mainly through reactivation or following recent Mycobacterium tuberculosis (re)infection. Within a DNA fingerprint-defined cluster of TB cases, reactivation cases are assumed to be the source of infection for subsequent secondary cases. As HIV-positive TB cases are less likely to be source cases, equal or higher clustering in HIV-positives would suggest that HIV mainly increases the risk of TB following recent infection.

METHODS: A systematic review was conducted to identify all studies on TB clustering and HIV infection in HIV-endemic populations. Available individual patient data from eligible studies were pooled to analyse the association between clustering and HIV.

RESULTS: Of seven eligible studies, six contributed individual patient data on 2116 patients. Clustering was as, or more, likely in the HIV-positive population, both overall (summary OR 1.26, 95%CI 1.0–1.5), and within age groups (OR 1.50, 95%CI 0.9–2.3; OR 1.00, 95%CI 0.8–1.3 and OR 2.57, 95%CI 1.4–5.7) for ages 15–25, 26–50 and >50 years, respectively.

CONCLUSIONS: Our results suggest that HIV infection mainly increases the risk of TB following recent M. tuberculosis transmission, and that TB control measures in HIV-endemic settings should therefore focus on controlling M. tuberculosis transmission rather than treating individuals with latent M. tuberculosis infection.