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Table 1 Current tuberculosis classification for U.S. immigration applicants

From: Tuberculosis progression rates in U.S. Immigrants following screening with interferon-gamma release assays

TB classification Status Description
No TB classification No evidence of TB infection or disease
A Smear or culturea positive pulmonary TB. Typically requires treatment prior to U.S. entry.
B1-Pulmonary 1. Suspected active pulmonary TB based on clinical findings but with negative sputum smears and culturesa
2. History of pulmonary TB, treatment complete
B1-Extrapulmonary Extrapulmonary TB
B2 TST ≥ 10 mm or positive IGRA but otherwise negative TB evaluation (LTBI)
B3 Recent close contact with a known active TB case and TST/IGRA negative
  1. Abbreviations: TB tuberculosis, LTBI latent tuberculosis infection, TST tuberculin skin test
  2. aCultures were gradually introduced into the overseas screening process from 2007–2014