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Background: Most people exposed to M. tuberculosis show no evidence of clinical disease. Five to 10% of individuals with latent infection progress to develop overt disease during their life time. Identification of people with latent TB infection will increase case detection rates and may dictate new treatment policies to control tuberculosis. This study aimed to determine LTBI point prevalence in a population from Sudan using two different diagnostic methods: the tuberculin skin test (TST) and the IFN-γ release assay (IGRA).
Methods: This was a prospective, community-based and case-controlled study. Following informed consent, household contacts (HHCs; n = 98) of smear-positive index cases and Community controls (CCs; 186), were enrolled. Tuberculin skin test (TST), whole blood stimulation with ESAT-6/CFP-10 ± TB7.7 antigens or purified protein derivative (PPD) and IFN-γ levels determination with ELISA were performed. The levels of IFN-γ and TST induration between the CCs and the HHCs were compared using student t-test, Chi-square and Kappa coefficient. Pearson correlation test was used to compare TST and IFN-γ. P levels of <0.05 were considered significant.
Results: TST induration of ≥ 10 mm gave an LTBI point prevalence of 327 cases/1000 individuals among HHCs compared to 126 cases/1000 individuals among CCs (p = 0.000). PPD-induced IFN-γ release assay gave an LTBI point prevalence of 418 cases/1000 individuals among HHCs compared to 301 cases/1000 individuals among CCs (p =0.06). On the other hand ESAT-6/CFP-10 ± TB7.7-induced IFN-γ gave an LTBI point prevalence of 429 cases/1000 individuals among HHCs compared to 268 cases/1000 individuals among CCs (p = 0.01). IFN-γ productions levels induced by ESAT-6/CPF-10 ± TB7.7 antigens in HHCS and CCs were not significantly different from those induced by PPD (p = 0.7).
Conclusion: IFN-γ release assay (IGRA) gave higher LTBI point prevalence compared to TST in HHCs and CCs. PPD gave comparable results to ESAT-6/CFP-10 ± TB7.7 antigens in whole blood IFN-γ release, making it a cheap alternative to the recombinant antigens.
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http://dx.doi.org/10.1186/1471-2458-13-1128 | DOI Listing |
Clin Infect Dis
September 2025
Tuberculosis Unit, Department of Infectious Diseases, Bellvitge University Hospital-Bellvitge Biomedical Research Institute (IDIBELL), L'Hospitalet de Llobregat, Barcelona, Spain.
Background: This study builds on previous evidence to assess the risk of tuberculosis (TB) in patients treated with biologic therapies (BioT), the role of the interferon-γ-release assay (IGRA) QuantiFERON-TB (QFT) Gold as a stand-alone screening test, and whether periodic re-testing is warranted for patients with a negative pre-BioT screening.
Methods: A total of 1,368 patients starting BioT were screened for TB infection using four screening strategies over four consecutive periods: (1) two-step tuberculin skin test (TST); (2) two-step TST plus QFT Gold In-Tube; (3) single-step TST plus QFT Gold In-Tube; and (4) QFT Gold In-Tube (or QFT Gold Plus) alone. All patients with TB infection were offered preventive therapy.
Monaldi Arch Chest Dis
September 2025
Neuroscience, University of Leeds.
Traditionally, tuberculosis (TB) has been viewed as having two distinct manifestations, known as TB infection (TBI) and TB disease. The spectrum, however, has recently been expanded to include the elimination of TBI with the help of innate and/or adaptive immunity, TBI, incipient and subclinical TB disease, and TB disease. Epidemiologically speaking, identifying individuals with TBI is critical since diagnosis and treatment of TBI are essential in controlling the TB burden.
View Article and Find Full Text PDFMaedica (Bucur)
June 2025
Department of Dermatology, University Hospital of Ioannina, Ioannina, Greece.
Erythema induratum of Bazin (EIB) is a rare subcutaneous granulomatous disease that is considered to represent a form of tuberculin hypersensitivity. We present the case of a 74-year-old Bacillus Calmette-Guerin (BCG)-vaccinated female patient, who presented to our dermatology clinic with painful, erythematous purple nodules on the lower extremities. Clinical examination, histopathological analysis, a positive tuberculin skin test (TST) and interferon-gamma release assay (IGRA) supported the diagnosis of EIB.
View Article and Find Full Text PDFJ Clin Microbiol
August 2025
Department of Bacteriology, Animal and Plant Health Agency, Addlestone, United Kingdom.
Unlabelled: Bovine tuberculosis is an infectious livestock disease of global economic and zoonotic importance. Surveillance programs are largely dependent on the skin test that utilizes purified protein derivatives (PPDs) of tuberculin. PPDs suffer from a number of limitations regarding their production, characterization, and performance.
View Article and Find Full Text PDFPLOS Glob Public Health
August 2025
Department of Global Health, Boston University School of Public Health, Boston, Massachusetts, United States of America.
Tuberculin skin test (TST) remains the standard-of-care test for TB infection in many high TB-burden settings. Despite existing diagnostics overcoming challenges associated with TST implementation, there has been poor uptake programmatically. We conducted formative research into patients' and providers' perceptions of acceptability and usability of a novel IGRA test, called QIAreach QuantiFERON TB (or, QIAreach), compared to TST in a programmatic setting in Mexicali.
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