Current World Health Organisation (WHO) guidelines recommend the screening of airline passengers who have been seated in rows adjacent to a passenger with suspected pulmonary (lung) TB for longer than three hours.    It prohibits those with active TB from all commercial travel until they are no longer infectious, which is usually after two weeks of treatment for pulmonary TB, but could be longer if the TB is resistant.

Researchers said limited resources could be put to better use by countries on other more effective aspects of TB control than air passenger screening.

Dr Ibrahim Abubakar of the University of East Anglia, UK, who chaired the European Centre for Disease Prevention and Control (ECDC) working group on tuberculosis and air travel, reviewed 39 studies that addressed the transmission of TB during commercial air travel to determine if the recommendations were justifiable. About 13 studies involving more than 4328 passengers from six countries were analysed.

Only two of the studies showed convincing evidence of transmission related to air travel while the bulk showed no evidence of any association between air travel and TB transmission.

Ten out of 2761 passengers and crew members screened for TB were found to have converted from negative to positive TB skin reaction test (to determine high probability of progressing to active disease). No active transmission was reported to have resulted during air travel.

Researchers said the reason for this could be associated with the duration of exposure to those infected with the disease.

 ‘€œAlthough an airline cabin is a closed confined space, the cumulative duration of exposure is relatively short compared with households or other modes of transport where individuals might travel on the same route daily,’€ said researchers.

They said factors such as tracing passengers, contacting different national authorities, the cost of investigation and the number of those found to have TB among others made the process highly inefficient.    

 Abubakar said the burden of TB was relatively enormous in many countries including middle income countries.

‘€œMany of these countries do not have the resources to investigate incidents of tuberculosis related to air travel’€¦and resources might be better spent addressing other priorities of tuberculosis control and helping achieve all millennium development goals related to tuberculosis,’€ he said.

According to the WHO several cases of travellers with TB or multidrug resistant TB infecting fellow travellers and the crew were reported in 1999. This caused panic among passengers, health officials and airline companies and led to the screening recommendations.

The third edition of the WHO: Tuberculosis and air travel guidelines for prevention and control said that recommendations were based on the limited evidence available at the time. It involved investigations involving seven contagious TB patients and some 2 600 potentially exposed air travelers.

For more information on the study visit: http://press.thelancet.com/airtravel.pdf

To read the WHO guidelines visit: http://www.who.int