This was my Oped in yesterday's Boston Globe.
Flying clear of tuberculosis
By Marc Siegel | June 6, 2007
FOLLOWING the news of Andrew Speaker's honeymoon escapade, where he flew unchecked while harboring a resistant tuberculosis bug, many of my patients have begun to ask me what their risks are of catching TB on a plane. The simple answer I give them is "extremely low." Big HEPA filters screen out more than 99 percent of viral and bacterial particles, including tuberculosis. The risk of Speaker infecting another passenger when he reportedly wasn't coughing, had no fever, and was receiving some treatment is probably less than 1 percent. The chance of an actual case of serious TB resulting from this exposure is even less than that, as there has not yet been a single case of active tuberculosis found to be the result of exposure on a plane.
Speaker suffers from the extensively drug resistant kind of tuberculosis, which is quite rare, with only 49 cases reported in the United States since 1993. TB itself is common, infecting one-third of the world's population, with more than 8 million people getting sick from it every year. Even with billions of airplane passengers every year, the plane is an unlikely place for TB transmission. There have been several small studies that have followed exposure to active TB on planes. From 1992 to 1994, the Centers for Disease Control and Prevention followed six passengers and a crew member who had TB in their sputum and exhibited active symptoms. Of the 2,600 contacts of these TB patients (two were deliberately flying without alerting the airline, the other five didn't know they had TB), only a few people showed subsequent transmission of TB and none got sick.
These patients were not only much sicker than Speaker, they were spewing TB in their sputum. The gold standard of transmissibility is the presence of the tuberculosis bacillus in the sputum or mucous of a patient. Speaker has been tested repeatedly, and his mucous is clear.
I have worked on the Chest Service of Bellevue Hospital where Speaker was briefly interned. It is routine practice for doctors there to remove masks and allow patients to roam the ward and even go home once their mucous tests negative. Speaker was no different. Isolation only became necessary once it was determined that his TB was so resistant that none of the standard treatments work for it. The fact that his brand of TB is so difficult to cure makes it that much more important to prevent spread even to a single person.
Speaker's case is a wakeup call for improved patient compliance. TB drug resistance is a growing problem, in part due to patients stopping their medicines partway through the treatment. It is often the same patients who don't take their medicines who also don't exercise the proper caution and put others at some risk. This is a good time for public health to employ more advanced genetic techniques to detect all drug resistance earlier and then restrict travel on an as-needed basis.
It is also a good time for public health officials to learn to communicate risk through facts rather than fear. Because of media dramatizations of rare killers, we tend to overpersonalize the dangers of the latest mystery bacteria or virus. Worldwide, tuberculosis itself is well worth being afraid of, but the numbers in the United States are much lower (14,000 cases per year). Americans fear it more now because of the hype, much as we once feared anthrax, smallpox, Mad Cow Disease, bird flu, and SARS. It is human nature to fear the unknown, but it is not good science.
Our civil rights should protect us from excess scrutiny every time we board a plane. But fear and distrust tend to erode these rights, which is why it is so important that we draw the right conclusions from the Speaker case.
Tuberculosis, a tiny hook-shaped airborne bacteria, is transmitted by deep coughing and prolonged exposure. Initial infections are generally very mild and TB goes on to cause significant disease in only 5 percent of cases, many of whom suffer from HIV or other chronic diseases.
More than 2 billion passengers fly on planes every year, but there has yet to be a documented case of someone getting sick with TB from an airplane exposure. Though TB kills close to 2 million people per year worldwide and cannot be trivialized, the more important lesson from Speaker is about public and media overreaction to remote risks.