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
