Progression to active tuberculosis, but not transmission, varies by Mycobacterium tuberculosis lineage in the Gambia

Bouke C. De Jong, Philip C. Hill, Alex Aiken, Timothy Awine, Martin Antonio, Ifedayo M. Adetifa, Dolly J. Jackson-Sillah, Annette Fox, Kathryn DeRiemer, Sebastien Gagneux, Martien W. Borgdorff, Keith P W J McAdam, Tumani Corrah, Peter M. Small, Richard A. Adegbola

Research output: Contribution to journalArticlepeer-review

219 Scopus citations


Background. There is considerable variability in the outcome of Mycobacterium tuberculosis infection. We hypothesized that Mycobacterium africanum was less likely than M. tuberculosis to transmit and progress to tuberculosis disease. Methods. In a cohort study of patients with tuberculosis and their household contacts in The Gambia, we categorized 1808 HIV-negative tuberculosis contacts according to exposure to M. tuberculosis or M. africanum. Positive skin test results indicated transmission, and development of tuberculosis during 2 years of follow-up indicated progression to disease. Results. Transmission rates were similar, but rates of progression to disease were significantly lower in contacts exposed to M. africanum than in those exposed to M. tuberculosis (1.0% vs. 2.9%; hazard ratio [HR], 3.1 [95% confidence interval {CI}, 1.1-8.7]). Within M. tuberculosis sensu stricto, contacts exposed to a Beijing family strain were most likely to progress to disease (5.6%; HR relative to M. africanum, 6.7 [95% CI, 2.0-22]). Conclusions. M. africanum and M. tuberculosis transmit equally well to household contacts, but contacts exposed to M. africanum are less likely to progress to tuberculosis disease than those exposed to M. tuberculosis. The variable rate of progression by lineage suggests that tuberculosis variability matters in clinical settings and should be accounted for in studies evaluating tuberculosis vaccines and treatment regimens for latent tuberculosis infection.

Original languageEnglish (US)
Pages (from-to)1037-1043
Number of pages7
JournalJournal of Infectious Diseases
Issue number7
StatePublished - Oct 1 2008

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Immunology


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