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Interview: Disease Expert on Rare TB Case

Posted on: Tuesday, 5 June 2007, 18:00 CDT

By ROSALIE WESTENSKOW

Recent trans-Atlantic air travel by a man infected with a rare strain of tuberculosis has raised serious public health concerns and exposed a communication meltdown between medical authorities and government officials.

Atlanta attorney Andrew Speaker has an extremely drug-resistant strain of the disease, more dangerous and likely to cause fatalities than ordinary TB. During his May travels to Europe and back, Speaker, currently isolated in a Denver hospital, potentially exposed hundreds of his fellow passengers to the disease.

Since Speaker's return to the United States on May 24, controversy has emerged regarding how he contracted the disease, whose responsibility it was to keep him off commercial flights and what can be done in the future to prevent similar incidences.

No single person or institution can be pointed out as the culprit, said Richard Wenzel, president of the International Society for Infectious Diseases, an organization that attempts to prevent and control global infections.

A number of factors ... (including) administrative and legal deficiencies regarding responsibility internationally; weaknesses in border security; the lack of individual patient responsibility; (and) confusing, mixed messages from medical authorities, all show us how unprepared we are to manage the threat of global transmission, Wenzel told United Press International.

The story behind Speaker's unfortunate journey extends far beyond one infection, requiring a look at infectious disease history to understand.

Q: How do resistant strains like this develop, particularly for TB?

A: Each time an organism multiplies, there's always a small risk, like one in a million or so, that it will escape (DNA) proofreading and develop resistance. They're so low in numbers when you think about it ... that most of the time that's not a problem. However, as we bombard infections with currently available drugs, we knock off all the susceptible population, and what emerges is the population of really rare, resistant organisms that now can overwhelm the person.

Q: With the increasing use of antibiotics, should we then expect to see an increasing number of these types of strains developing?

A: Absolutely, and the key point is this: the priority has to be on the development of a new and effective vaccine. We will never control tuberculosis without a vaccine.

Q: Why would a vaccine be more effective?

A: Because organisms don't develop resistance to vaccines. ... The one really major triumph of infectious disease is the control of smallpox, almost exclusively because of an effective vaccine. Today, we still don't have an effective drug for smallpox.

Q: What are the barriers to developing an effective vaccine for TB?

A: I think it's part technical and part biological. We have to find a key part of the organism that exists in all organisms -- a key protein, for example, or a key enzyme -- and then make sure that if you knock that out by antibodies that the organism won't live. And that's been a sort of biological, medical challenge. I think a second is that there has to be a lot more resources going into (the development) of a vaccine for tuberculosis.

Q: Considering the ability of this particular TB strain to resist drugs, how do you think Speaker is being treated?

A: What you wind up doing is running the organism against any known antibiotic to see if there might be some that are effective. ... I haven't seen the cocktail of antibiotics this person's taking, but what I read is that he's on five different antibiotics. And the reason that you want multiple antibiotics is that by using many antibiotics, you reduce the risk that the organism will develop quick resistance to any one of them.

Q: What is the hope for a cure for Speaker or other people who contract this strain?

A: It's hard to know because I don't know his situation, but, in general, this carries a very high mortality rate of 50 percent or more. So I think one of the key points that's been lost ... (is that) this person's a real patient right now. He's a victim of an infection which he surely didn't want, and he has some risk of not surviving.

Q: So far, health officials haven't identified TB in any of Speaker's fellow passengers, but do you think there's a high likelihood, in this case or others, of somebody developing TB from exposure aboard an airplane?

A: There was a similar story of a passenger with TB who flew from Chicago to Hawaii that was published about 10 years ago in the New England Journal of Medicine. And, although the numbers were small, about 30 percent of the passengers who were either up or behind two rows (of the infected person), became infected. ... So there's no question that, generically, patients with TB on an airplane can infect others.

Q: Is there any way to keep passengers with diseases like this off of airplanes or are there any efforts being taken to do so?

A: No ... there's almost no screening of passengers. I think if someone fainted or just looked really horrible they might be screened off the plane. The only other thing we've had experience with is certain epidemics, like the SARS epidemic. Almost everybody with SARS had a fever, so they were screening people at the airport for fevers. That will keep off SARS, but it will keep off people with other infections as well, so it's not pinpointing accuracy, but at least it works to keep (those with) life-threatening infections off.

Q: In this case, where health officials knew about his condition, what could have been done further to keep Speaker from spreading the disease?

A: If he had any inkling that he had active tuberculosis -- and there's going to be debate, apparently, about how much he knew or didn't know -- I think he has to accept some responsibility for having a serious infection. In the future, I think what could be done to address some of these shortcomings is if the World Health Organization and the Centers for Disease Control and some public health authorities from different countries got together ... to create communication guidelines to contain travelers with serious infections. Apparently, there are no such guidelines today, so the communication broke down.

Q: What is the potential for an epidemic occurring as a result of infected airplane passengers?

A: The fact that, within two weeks, a person with a serious infection took seven airline flights to five countries exposing around 500 people shows the potential for global transmission of a life-threatening disease in a very short time.

Q: Is there anything other passengers can do to protect themselves?

A: It's very, very difficult if busy passengers are flying, and they don't know what the person nearby has, particularly if it's two rows away. Many people might carry a mask or something like that, but routinely no one's going to wear one of those thick masks for long flights. It's too uncomfortable ... you can't say that's a practical solution.

Source: United Press International

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