Latent tuberculosis in HIV positive, diagnosed by the M. tuberculosis specific interferon-gamma test

Respir Res. 2006 Apr 1;7(1):56. doi: 10.1186/1465-9921-7-56.


Background: Although tuberculosis (TB) is a minor problem in Denmark, severe and complicated cases occur in HIV positive. Since the new M. tuberculosis specific test for latent TB, the QuantiFERON-TB In-Tube test (QFT-IT) became available the patients in our clinic have been screened for the presence of latent TB using the QFT-IT test. We here report the results from the first patients screened.

Methods: On a routine basis the QFT-IT test was performed and the results from 590 HIV positive individuals consecutively tested are presented here. CD4 cell count and TB risk-factors were recorded from patient files.

Main findings: 27/590(4.6%) of the individuals were QFT-IT test positive, indicating the presence of latent TB infection. Among QFT-IT positive patients, 78% had risk factors such as long-term residency in a TB high endemic area (OR:5.7), known TB exposure (OR:4.9) or previous TB disease (OR:4.9). The prevalence of latent TB in these groups were 13%, 16% and 19% respectively. There was a strong correlation between low CD4 T-cell count and a low mitogen response (P < 0.001;Spearman) and more patients with low CD4 cell count had indeterminate results.

Conclusion: We found an overall prevalence of latent TB infection of 4.6% among the HIV positive individuals and a much higher prevalence of latent infection among those with a history of exposure (16%) and long term residency in a high endemic country (13%). The QFT-IT test may indeed be a useful test for HIV positive individuals, but in severely immunocompromised, the test may be impaired by T-cell anergy.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • AIDS-Related Opportunistic Infections / blood
  • AIDS-Related Opportunistic Infections / diagnosis*
  • AIDS-Related Opportunistic Infections / epidemiology*
  • AIDS-Related Opportunistic Infections / microbiology
  • Adult
  • CD4 Lymphocyte Count
  • CD4-Positive T-Lymphocytes / chemistry
  • CD4-Positive T-Lymphocytes / metabolism
  • CD4-Positive T-Lymphocytes / microbiology
  • Denmark / epidemiology
  • Diagnostic Tests, Routine / methods
  • Female
  • HIV
  • HIV Infections / complications
  • Humans
  • Interferon-gamma / analysis
  • Interferon-gamma / blood*
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / physiology*
  • Prevalence
  • Risk Factors
  • Tuberculosis, Pulmonary / blood
  • Tuberculosis, Pulmonary / diagnosis*
  • Tuberculosis, Pulmonary / epidemiology*
  • Tuberculosis, Pulmonary / etiology


  • Interferon-gamma