Little risk of TB transmission during flights: Study
Reported February 24, 2010
NEW DELHI: The World Health Organisation (WHO)’s international guideline for the control of tuberculosis in relation to air travel — tracing passengers who sat for longer than eight hours in rows adjacent to people with pulmonary TB — may be futile and exaggerated.
A British scientist who reviewed evidence from 39 studies that looked at transmission of TB during commercial air travel found that there was little risk of TB transmission linked to air journeys.
Ibrahim Abubakar from the University of East Anglia (UK), who chaired the European Centre for Disease Prevention and Control’s (ECDC) working group on TB and air travel, after reviewing the studies involving more than 4,328 passengers from six countries found only two studies that reported realistic evidence of transmission.
Dr Abubakar, who wanted to verify if current international recommendations were justified, has reported in the medical journal `Lancet’ that tracing and screening air passengers and crew who might have been exposed to a person with TB was a highly inefficient resource-intensive process.
The scientist said, “Although 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.”
Director of India’s revised TB control programme Dr L S Chauhan agreed with Dr Abubakar’s conclusion.
Dr Chauhan told TOI a TB patient on treatment was allowed to travel on an airplane whereas those still not on treatment should avoid air travel.
“TB can spread only if an airplane stands still for over half-an-hour after the doors have been shut, which usually does not happen. However, even if a TB patient takes a long flight, he will not spread the TB bacteria to others because the air inside the flight is constanlty being refreshed when the plane is moving,” Dr Chauhan said.
Experts say most planes now have high-efficiency air filtration designed to trap germs bigger than 0.3 nanometres, which means it is possible to trap the TB bacterium. The cabin air is renewed over 15 times in an hour.
Dr Abubakar’s review indicates that compared with the actual number of passengers with TB, the resource-intensive process is highly inefficient because of the difficulty of tracing air passengers, the complexity of contacting different national authorities, the poor response from passengers who are usually told that their risk is very low and the cost of investigation.
“Tracing and screening is advocated in international guidelines. Of all the passengers and crew screened in the studies I reviewed, only 10 were found to have converted from a negative to a positive tuberculin skin reaction with a high probability of progressing to active disease. Significantly, there were no reports of cases of active TB resulting from transmission during air travel,” Dr Abubakar said.
“The burden of TB in many countries, including some middle-income countries, remains high. Many of these countries do not have the resources to investigate incidents of TB related to air travel and resources might be better spent addressing other priorities of TB control,” he added.
Source : THE TIMES OF INDIA
