A Case of Active Tuberculosis in a Cabin Crew: The Results of Contact Tracing

Abstract

Transmission of communicable diseases on board aircraft is of considerable concern for passengers and aircrew. Previously published estimates of risk of tuberculosis (TB) transmission have been highly variable. Furthermore, very few studies have been published for active TB in aircrew. The public health authorities advised the Medical Advisor of an airline that a cabin crewmember had been diagnosed with active TB. Contact tracing was done for the cabin crew who worked with the index case for more than 8 h. Cabin crewmembers were divided in two groups according to their exposure and had one tuberculin skin test (TST) more than 8 wk after the last exposure. Those with a TST > or = 5 mm have been recommended to have a QuantiFERON-TB Gold In-Tube (QFT) assay. Among the 56 identified contacts, 32 agreed to be evaluated, of whom 6 (19%) had a TST > or = 5 mm. Of those six, four underwent a QFT with one positive result. None had active TB. The percentages of positives in the two exposure groups were similar. All the positive contacts were born in Canada in the period when the childhood Bacille Calmette-Guérin (BCG) vaccination program was in effect. The same percentage of positives in the two exposure groups, the proportion of positive contacts below the expected rate in Canadians, and the high proportion of QFT negative among the TST positive contacts suggest that transmission of TB to the cabin crew is unlikely.