Malnutrition and helminth infection affect performance of an interferon gamma-release assay.
OBJECTIVE
We sought to compare the tuberculin skin test (TST) to the QuantiFERON-TB Gold In-Tube assay (QFT-IT) and assess the effects of malnourishment and intestinal helminth infection on QFT-IT results.


METHODS
In this population-based cross-sectional study from Dhaka, Bangladesh, we screened children for latent tuberculosis infection with the QFT-IT and TST. We assess the agreement between the TST and QFT-IT, risk factors associated with indeterminate QFT-IT results, and magnitude of interferon γ (IFN-γ) production.


RESULTS
Three hundred and two children (aged 11-15.3 years) were enrolled, including 93 (30.8%) who were malnourished. Of 251 participants who provided stool samples, 117 (46.6%) were infected with Ascaris lumbricoides and/or Trichuris trichiura. TST results were positive (≥10 mm) for 101 (33.4%) children and negative for 201 (66.6%) children. QFT-IT results were positive for 107 (35.4%) children, negative for 121 (40.1%) children, and indeterminate for 74 (24.5%) children. Agreement between the tests was moderate (κ = 0.55 [95% confidence interval: 0.44-0.65]; P < .0001) when excluding indeterminate results. Children with indeterminate QFT-IT results were separately compared with children with positive and negative QFT-IT results; malnutrition (P = .0006 and .0003), and helminth infection (P = .05 and .02), and the statistical interaction between these 2 terms (P = .03 and .004) were associated with indeterminate results. Higher levels of IFN-γ in response to tuberculosis antigens were associated with positive TST results (P < .0001); lower levels were associated with malnutrition (P = .02).


CONCLUSIONS
Malnutrition and helminth infections were associated with indeterminate QFT-IT results. Therefore, the presence of such conditions may limit the interpretability of QFT-IT results in children.
Division of Infectious Diseases and International Health, University of Virginia, Charlottesville, Virginia, USA. tthomasheysell@gmail.com
Tania A
TA
Thomas
Dinesh
D
Mondal
Zannatun
Z
Noor
Lei
L
Liu
Masud
M
Alam
Rashidul
R
Haque
Sayera
S
Banu
Haiyan
H
Sun
Kristine M
KM
Peterson
D000293:Adolescent; D000818:Animals; D001459:Bangladesh / Q000453:epidemiology; D002353:Carrier State; D002648:Child; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005243:Feces / Q000469:parasitology; D005260:Female; D005500:Follow-Up Studies; D006373:Helminthiasis / Q000097:blood / Q000150:complications* / Q000453:epidemiology; D006376:Helminths / Q000302:isolation & purification; D006801:Humans; D015994:Incidence; D007371:Interferon-gamma / Q000097:blood / Q000378:metabolism*; D008297:Male; D044342:Malnutrition / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D008403:Mass Screening; D015203:Reproducibility of Results; D012189:Retrospective Studies; D012307:Risk Factors; D014374:Tuberculin Test / Q000379:methods; D014376:Tuberculosis / Q000097:blood / Q000150:complications / Q000453:epidemiology
D007371:Interferon-gamma