Tuberculosis Risk in the Returning Traveler: Assessing TB Test Conversion Among Routinely Tested Patients at an Asian American Health Center

Abstract Background In the U.S., testing for latent tuberculosis infection (LTBI) is recommended for persons from higher-tuberculosis (TB)-prevalence countries, but guidelines do not address repeat testing for persons with international travel. Methods Using 2010-2022 data from a Californian federally qualified health center serving an Asian American population, we measured the incidence of TB test conversion (negative to positive result) and proportion of test converters receiving treatment among routinely-tested patients (i.e. patients with no history of TB infection, at least one prior negative result, and annual or biennial TB testing). We performed a nested case-control study to measure the association between TB test conversion and travel outside the U.S. Results Of 5,668 patients receiving routine TB testing at annual/biennial frequencies, conversions occurred in 117 patients with TB skin tests (2.9%) and 52 patients with interferon-gamma release-assays (3.2%); the overall test conversion incidence rate was 2.1/100 person-years. LTBI treatment was initiated in 57% of test converters. Two patients were diagnosed with TB disease after test conversion, representing a two-year TB incidence rate of 0.35/100 person-years. Patients with documented international travel had 1.95-fold increased odds of TB test conversion (aOR 95% CI 1.07, 3.57) compared to patients without documented travel, with most travel occurring in medium or high-TB-prevalence countries. Conclusions Within a 13-year study period, among a routinely tested population at higher risk of TB infection due to race and nativity, risk of TB test conversion was low. However, recent travel to higher-TB-prevalence settings nearly doubled the odds of TB test conversion.