Smoking, BCG and employment and the risk of tuberculosis infection in HIV-infected persons in South Africa.

Abstract

BACKGROUND:

The increased susceptibility to latent tuberculosis infection (LTBI) of HIV-1-infected persons represents a challenge in TB epidemic control. However few studies have evaluated LTBI predictors in a generalized HIV/TB epidemic setting.

METHODS:

The study recruited 335 HIV-infected participants from Khayelitsha, Cape Town between February 2008 and November 2010. Tuberculin skin tests and interferon-gamma release assays were performed on all participants and active TB excluded using a symptom screen, TB microscopy and culture.

RESULTS:

LTBI prevalence was 52.7% and 61.2% (TST and IGRA respectively). Being a recent TB contact (OR 2.07; 95% C.I. 1.15-3.69) was associated with TST positivity. Participants with a CD4>200 had a two-fold higher risk of IGRA positivity compared to those with CD4 counts <200 (OR 2.07; 95% C.I. 0.99-4.34). There was also a 19% increase in IGRA positivity risk for every additional year of schooling and a strong association between years of schooling and employment (p = 0.0004). A decreased risk of IGRA positivity was observed in persons with a BCG scar (OR 0.46; 95% C.I. 0.31-0.69) and in smokers (OR 0.47; 95% C.I. 0.23-0.96).

CONCLUSION:

We report the novel findings of a decreased risk of IGRA positivity in HIV-infected smokers possibly due to decreased interferon production, and in the persons with a BCG scar suggesting a protective role for BCG in this population. We also found an increased risk of TST positivity in employed persons, possibly due to ongoing transmission in public modes of transport.

• Authors: Tolu Oni, Hannah P Gideon, Nonzwakazi Bangani, Relebohile Tsekela, Ronnett Seldon, Kathryn Wood, Katalin A Wilkinson, Rene T Goliath, Tom H M Ottenhoff, Robert J Wilkinson
• Journal: PloS one (PLoS One) Vol. 7 Issue 10 Pg. e47072 ( 2012) ISSN: 1932-6203 [Electronic] United States
• PMID: 23056584 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Topics

• Adult
• Employment
• Female
• HIV Infections (epidemiology, immunology)
• Humans
• Interferon-gamma Release Tests
• Male
• Mycobacterium bovis (immunology)
• Smoking (adverse effects)
• South Africa (epidemiology)
• Tuberculin Test
• Tuberculosis (epidemiology, immunology)