A case of infectious tuberculosis on two long-haul aircraft flights: contact investigation

Aim. During a five-week period in 1996, a passenger with highly infectious tuberculosis travelled on five long-haul aircraft flights. We investigated passengers and crew on two of these flights to identify whether transmission of Mycobecterium tuberculosis had occured. Methods. Crew and passengers were identified from airline and immigration records. Contacts were notified of their exposure and invited to attend their local public health clinic. At the clinic, a questionnaire was administered by a public health worker, and a Mantoux skin test was perfomed. When indicated, a second test was carried out twelve weeks later. Test positivity and conversion were defined according to the 1996 New Zealand tuberculosis control guidelines. Results. Data were obtained on 206 (87%) of the 238 contacts. Twenty four contacts had a positive Mantoux test result, four of which were conversions. All of these contacts had a least one other major risk factor for a positive result, such as a previous BCG vaccination (n=17) or having lived in a country in which tuberculosis is endemic (n=15). To our knowledge, no contacts have subsequently developed tuberculosis disease. Conclusions. The investigation produced inconclusive evidence about the hypothesis that Mycobacterium tuberculosis was transmitted on one or both of these flights.