title: Risk of tuberculosis among air passengers estimated by interferon gamma release assay: survey of contact investigations, Japan, 2012 to 2015.
abstract: Although the World Health Organization recommends contact investigations around air travel-associated sputum smear-positive tuberculosis (TB) patients, evidence suggests that the information thus obtained may have overestimated the risk of TB infection because it involved some contacts born in countries with high TB burden who were likely to have been infected with TB in the past, or because tuberculin skin tests were used, which are less specific than the interferon gamma release assay (IGRA) particularly in areas where Bacillus Calmette-Guérin (BCG) vaccination coverage is high. We conducted a questionnaire survey on air travel-associated TB contact investigations in local health offices of Japan from 2012 to 2015, focusing on IGRA positivity. Among 651 air travel-associated TB contacts, average positivity was 3.8% (95% confidence interval (CI): 2.5-5.6) with a statistically significant increasing trend with older age (p < 0.0094). Positivity among 0-34 year-old contacts was 1.0% (95% CI: 0.12-3.5%), suggesting their risk of TB infection is as small as among Japanese young adults with low risk of TB infection (positivity: 0.85-0.90%). Limiting the contact investigation to fewer passengers (within two seats surrounding the index case, rather than two rows) seems reasonable in the case of aircraft with many seats per row.
authors.affiliation: Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Matsuyama 3-1-24, Kiyose city, Tokyo, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Ota
authors.affiliation: Research Institute of Tuberculosis, Japan Anti-Tuberculosis Association, Matsuyama 3-1-24, Kiyose city, Tokyo, Japan.
authors.forename: Seiya
authors.initials: S
authors.lastname: Kato
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D000401:Aircraft; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003141:Communicable Diseases / Q000635:transmission; D016358:Contact Tracing / Q000706:statistics & numerical data*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007371:Interferon-gamma / Q000097:blood; D059425:Interferon-gamma Release Tests / Q000379:methods*; D008297:Male; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D011795:Surveys and Questionnaires; D014195:Travel; D014376:Tuberculosis / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D015415:Biomarkers; D007371:Interferon-gamma
keywords: air travel; air-borne infections; epidemiology; interferon gamma release assay; outbreaks; tuberculosis