Immune correlates of acute Mycobacterium tuberculosis infection in household contacts in Kampala, Uganda.
To determine immunologic and epidemiologic correlates of acute Mycobacterium tuberculosis infection in household contacts of infectious tuberculosis cases, we performed a prospective, community-based cohort study of index cases and their household contacts in Kampala, Uganda. Contacts were evaluated for tuberculin skin test (TST) conversion over two years. Interferon-gamma expression was measured using a whole blood assay after stimulating with M. tuberculosis culture-filtrate. In 222 contacts with a TST less than 5 mm at baseline, the one-year rate of TST conversion was 27%. The TST conversion was associated with the infectiousness of the index case and proximity of contact. Interferon-gamma levels at baseline were greater among TST converters compared with those who did not convert. The risk of TST conversion increased four-fold as the baseline interferon-gamma increased 10-fold, but only in contacts with BCG vaccination. In household contacts of tuberculosis, interferon-gamma responses to non-specific mycobacterial antigens may be used to make an early diagnosis of tuberculosis infection, especially in resource-limited settings where bacille Calmette-Guérin vaccination is commonly used.
Whalen
Christopher C
CC
Department of Epidemiology and Biostatistics, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA. ccw@case.edu
Chiunda
Allan
A
Zalwango
Sarah
S
Nshuti
Lorna
L
Jones-Lopez
Edward
E
Okwera
Alphonse
A
Hirsch
Christina
C
Peters
Pierre
P
Boom
W Henry
WH
Mugerwa
Roy D
RD
D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D007371:Interferon-gamma / Q000032:analysis* / Q000096:biosynthesis; D008297:Male; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D011446:Prospective Studies; D012307:Risk Factors; D014374:Tuberculin Test; D014376:Tuberculosis / Q000453:epidemiology* / Q000276:immunology*; D014454:Uganda / Q000453:epidemiology
D007371:Interferon-gamma