Persistent latent tuberculosis reactivation risk in United States immigrants

Current guidelines limit latent tuberculosis infection (LTBI) evaluation to persons in the United States less than or equal to 5 years based on the assumption that high TB rates among recent entrants are attributable to high LTBI reactivation risk, which declines over time. We hypothesized that high postarrival TB rates may instead be caused by imported active TB.

Estimate reactivation and imported TB in an immigrant cohort.

We linked preimmigration records from a cohort of California-bound Filipino immigrants during 2001-2010 with subsequent TB reports. TB was likely LTBI reactivation if the immigrant had no evidence of active TB at preimmigration examination, likely imported if preimmigration radiograph was abnormal and TB was reported less than or equal to 6 months after arrival, and likely reactivation of inactive TB if radiograph was abnormal but TB was reported more than 6 months after arrival.

Among 123,114 immigrants, 793 TB cases were reported. Within 1 year of preimmigration examination, 85% of TB was imported; 6 and 9% were reactivation of LTBI and inactive TB, respectively. Conversely, during Years 2-9 after U.S. entry, 76 and 24% were reactivation of LTBI and inactive TB, respectively. The rate of LTBI reactivation (32 per 100,000) did not decline during Years 1-9.

High postarrival TB rates were caused by detection of imported TB through active postarrival surveillance. Among immigrants without active TB at baseline, reported TB did not decline over 9 years, indicating sustained high risk of LTBI reactivation. Revised guidelines should support LTBI screening and treatment more than 5 years after U.S. arrival.