QuantiFERON®-TB Gold In-Tube reliability for immigrants with parasitic infections in Boston, USA

SETTING: Accurate testing and treatment for latent tuberculosis infection is necessary for tuberculosis elimination. Certain parasite infections are associated with increased tuberculin skin test positivity; species-specific effects on QuantiFERON-TB Gold In-Tube (QGIT) are not yet described. OBJECTIVE: We sought to determine whether infection with helminths or protozoa affects QGIT results. DESIGN: We retrospectively analyzed QGIT and parasite testing results for immigrants screened in Boston from 2012–2017. We also prospectively measured cytokines in QGIT supernatants for a subset (n=68) with 1) helminths, 2) Blastocystis hominis, 3) other protozoa, and 4) no parasites. RESULTS: Of 527 immigrants screened, 141 (26.8%) had a positive QGIT and 229 (43.4%) had parasites detected: 27/527 (5.1%) helminths and 202/527 (38.3%) protozoa. Cytokine analysis revealed increased IL-10 concentrations with protozoa (p=0.04), and non-significantly higher Th2 concentrations with helminths compared to no parasites. No significant differences emerged in QGIT positivity or interferon-gamma concentrations in any group. CONCLUSION: This study supports use of QGITs in parasite-endemic settings.