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


RESULTS
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.


CONCLUSIONS
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.
Department for Infectious Diseases, University Hospital, Hvidovre 2650, Denmark. ibrock@dadlnet.dk
Inger
I
Brock
Morten
M
Ruhwald
Bettina
B
Lundgren
Henrik
H
Westh
Lars R
LR
Mathiesen
Pernille
P
Ravn
D017088:AIDS-Related Opportunistic Infections / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology* / Q000382:microbiology; D000328:Adult; D018791:CD4 Lymphocyte Count; D015496:CD4-Positive T-Lymphocytes / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology; D003718:Denmark / Q000453:epidemiology; D003955:Diagnostic Tests, Routine / Q000379:methods; D005260:Female; D006678:HIV; D015658:HIV Infections / Q000150:complications; D006801:Humans; D007371:Interferon-gamma / Q000032:analysis / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000502:physiology*; D015995:Prevalence; D012307:Risk Factors; D014397:Tuberculosis, Pulmonary / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology
D007371:Interferon-gamma