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Air travellers with TB triple since 2006

Authorities are discovering a growing number of tuberculosis patients who have travelled by air while contagious, several of them potentially exposing other passengers to the most worrisome, drug-resistant strains of the disease, public-health alerts suggest.

Reports of infectious air passengers more than tripled to 65 last year from 18 in 2006, prompting extensive attempts to warn travellers who might have been contaminated, Public Health Agency of Canada scientists say.

The agency notified 2,472 passengers who sat close to the TB patients on their flights between 2006 and 2008, though some airlines refused to divulge their passenger manifests, according to a just-published article.

Outside experts say the danger of contracting tuberculosis from someone on a plane is low, but called the statistical trend disquieting all the same.

“It is a concern whenever you have someone flying who has open TB,” said Dr. David Haldane, a microbiologist at Dalhousie University. “It’s certainly not desirable…. The more people you have flying, the more risk you have.”

Although the agency does not routinely follow up with passengers, it has yet to hear from local officials about any who tested positive, said Dr. Edward Ellis, the organization’s head of tuberculosis control. Still, he said it is important to track down contacts, especially when some risk contracting drug-resistant disease.

“I’d be much more concerned if the attitude was ‘Well, the risk is very low, so we’re not going to follow up at all,’ ” Dr. Ellis said. “If I’m a passenger and I’m sitting next to an infectious TB case, I know eventually I’m going to be contacted, and they’re going to check me.”

The increased numbers are likely a result of rising levels of air travel and more awareness of the question on the part of public-health units, he said.

The issue of infectious tuberculosis patients spending hours in the enclosed space of an airliner alongside hundreds of other people grabbed the world’s attention in 2007 when word got out that American Andrew Speaker had flown to Europe and back, with a stop in Canada, despite having multi-drug-resistant TB.

Tuberculosis is an airborne disease, meaning tiny particles remain suspended in the air for hours, said Dr. Wendy Wobeser, an infectious-disease specialist at Queen’s University.

Planes filter their cabin air, however, so the particles do not linger for long, and the greatest chance of being infected by a TB patient is on long flights, for those sitting within a couple of rows, she said. None of the people who sat close to Mr. Speaker tested positive. Most people who do get the infection can be cured with antibiotics.

Still, federal guidelines say that no one should board a plane—or frequent other crowded, public places—if they suffer from infectious tuberculosis.

The Public Health Agency of Canada received reports from local or international officials of 104 such patients taking flights into or out of Canada between 2006 and 2008, said its paper in the journal Travel Medicine and Infectious Disease. There were another 65 last year. Officials filed reports after diagnosing patients with tuberculosis and determining they likely flew while contagious.Nine had strains resistant to one or more antibiotics, including four who had multi-drug-resistant versions of the bacteria. Most were born outside Canada.

The agency identified 110 flights that fell under Canadian jurisdiction, then started the detective work. Although compliance has improved lately, airlines earlier ignored requests to turn over passenger manifests in five cases.

Even for the flights where patient manifests were released, actual contact information was not always available, so the agency used Canadian passport records and border-entry cards to fill in some of the blanks.

Affecting primarily the lungs, with such symptoms as chest pain and bloody coughing, tuberculosis still causes millions of deaths a year around the world. TB was a major killer in Canada, too, until the 1950s, when it started to disappear rapidly. It has levelled off in recent years to about 1,600 additional, active cases yearly, with new pockets among some recent immigrants and aboriginal people.

Given the relatively low risk posed by TB air passengers, the value of the federal program to track and investigate them is not absolutely clear, said Dr. Wobeser, who noted that some local tuberculosis programs, on the other hand, are quite under-funded.

“It is a costly intervention,” she said of the agency’s efforts. “I’d have to look at the actual yield to come to a conclusion about its effectiveness, its cost effectiveness.”

Via (The Nat’l Post)