Frequencies for Tuberculosis Picked Up on Airline Flights

Electron micrograph of M. tuberculosis courtesy of the Institut Pasteur image library.

Mycobacterium tuberculosis is a rod-shaped bacterium that can cause disseminated disease but is most frequently associated with pulmonary infections. The bacilli are transmitted by the airborne route and, depending on host factors, may lead to latent tuberculosis infection (sometimes abbreviated LTBI) or tuberculosis disease (TB).

Low level tuberculosis infections are routinely picked up on airplanes. Althought the CDC has documented only one case, anyone who flys regularly will need to apply tuberculosis frequencies multiple times per year. These frequencies should be checked when any noticeable decrease in lung function appears after an airline flight. People who run regularly may notice more difficulty breathing than usual.

Fortunately, the tuberculosis bacterium is easily knocked out with frequencies. However, it tends to become systemic and form a chronic infection when not eliminated quickly. The need for frequencies must then be checked periodically and applied as necessary.

Diagram from CDC. Published in N Engl J Med 1996;334:933-8.

Thomas A. Kenyon, M.D., M.P.H., Sarah E. Valway, D.M.D., M.P.H., Walter W. Ihle, M.P.A., Ida M. Onorato, M.D., and Kenneth G. Castro, M.D.
Background. In April 1994, a passenger withinfectious multidrug-resistant tuberculosis traveled oncommercial-airline flights from Honolulu to Chicago andfrom Chicago to Baltimore and returned one month later.We sought to determine whether she had infected any ofher contacts on this extensive trip.
Methods. Passengers and crew were identified from airline records and were notified of their exposure, asked to complete a questionnaire, and screened by tuberculin skin tests.
Results. Of the 925 people on the airplanes, 802 (86.7 percent) responded. All 11 contacts with positive tuberculin skin tests who were on the April flights and 2 of 3 contacts with positive tests who were on the Baltimore-to-Chicago flight in May had other risk factors for tuberculosis. More contacts on the final, 8.75-hour flight from Chicago to Honolulu had positive skin tests than those on the other three flights (6 percent, as compared with 2.3, 3.8, and 2.8 percent). Of 15 contacts with positive tests on the May flight from Chicago to Honolulu, 6 (4 with skin-test conversions) had no other risk factors; all 6 had sat in the same section of the plane as the index patient (P 0.001). Passengers seated within two rows of the index patient were more likely to have positive tuberculin skin tests than those in the rest of the section (4 of 13, or 30.8 percent, vs. 2 of 55, or 3.6 percent; rate ratio, 8.5; 95 percent confidence interval, 1.7 to 41.3; P 0.01).
Conclusions. The transmission of Mycobacterium tuberculosis that we describe aboard a commercial aircraft involved a highly infectious passenger, a long flight, and close proximity of contacts to the index patient. (N Engl J Med 1996;334:933-8.)

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