The New York Times’ website has a little list of "most e-mailed articles". It is sometimes frightening. The list is often topped by stories related to furniture decision dilemmas, private schools for macramé, 100 recipes with cauliflower, or the latest Apple iGadget. These subjects appear to be of utmost importance, setting aside news.
Every once in a while, however, a few important stories make the "most e-mailed" list. Some of them recently have related to public health, often the belated articles about a recent pandemic threat, which portray the sense that we yet again escaped a "superbug"–bird flu, SARS–that never really seemed to happen anyway (well, not to "us" at least), or just fizzled off like the latest winter storm. The most recent of these has been extensively drug-resistant (XDR) tuberculosis, a form of TB that is resistant to most available medications, and is therefore more difficult to treat than its drug-susceptible counterparts [1]. Americans were recently told of two separate incidences of XDR TB among airline passengers–an American defense lawyer, and an Indian national–both of whom knew about their disease status and chose to fly anyway [2]. The sense was one of appall–a kind of "How could you put us in danger? What right do you have…" and yet in many ways, the sense of appall could be directed at those who seemed shocked.
That reasoning is more understandable if we look closely at the worldwide picture of XDR TB, and its causes. The disease has appeared on every continent, and in nearly every country that has TB, including the
But increasingly, we are finding that "non-complaint" patients are not the origin, but the side-effect, of inadequate medical care. Many patients are not prescribed an adequate regimen by their doctors. In fact, the World Health Organization’s (WHO) guidelines instruct physicians to use a regimen that is often ineffective when patients are failing therapy [8]; this regimen often amplifies the drug resistance [9]. But it’s cheap to use this regimen, and avoid rapidly testing patients for drug-resistant TB to give them "second-line" therapy. Indeed, XDR TB in
We can understand why this is the case if we take the patients’ perspective. Patients with TB in many regions of
What complicates the picture is that some of these drug-resistant TB strains are transmissible, so the problem is not merely the build-up of resistant bacteria due to treatment interruptions and the difficulties of accessing effective drugs. Rather, some people catch already drug-resistant TB bacteria [18, 19].
What is particularly frightening is that the number one risk factor for them to have XDR TB was "hospitalization" [22]. In many of these regions, patients are admitted to hospital wards if they are too ill to stay home. Sometimes, given the media attention received by XDR TB, health officials will try to "quarantine" such patients out of fear that they may infect people in the community [23]. But there are rarely isolation facilities available. Patients will be detained in large rooms (often without adequate ventilation) with 40 or more other "suspects", many of whom are HIV-infected and therefore at greater risk of getting active, potentially infectious, TB [24]. It takes months to determine who has XDR, who has TB at all, and who just has a cough and possibly a pneumonia. During the time these patients stay together, many patients who did not have XDR TB will become "superinfected" with XDR TB, on top of whatever they already have [22]. A few bigger hospitals have a spare trailer home or additional room to put XDR TB patients, but the detection system takes a month or more to determine who has drug-resistant TB, while the median survival time of the XDR TB patients has been just 16 days after arrival getting tested at the hospital [21]. Most XDR TB patients die after they have been placed in circumstances where they could transmit the disease on the hospital ward, and before they can be isolated from other patients. That explains why so many patients who presented to hospitals with non-XDR TB or some other condition later returned and died with XDR TB, after being hospitalized with XDR TB patients but not exposed to XDR TB in the community [22].
Indeed, in spite of the focus on travelers on airplanes, the truth of the matter is that ventilation on airliners is actually sometimes much better than ventilation in some of these hospital wards, particularly in the hospitals located in the poorest areas affected by both HIV and TB [25, 26]. The risk of airplane transmission is remarkably low for most passengers [25], but on some hospital wards it would be difficult to avoid catching TB, particularly when being "detained" for a month or more in a stuffy room with several dozen other patients [24]. Some patients in
But ironically, this disconnect between patient realities and health system approaches is highlighted even by the airline passenger cases. In both
Why are these TB systems having so much trouble?
Indeed, Americans shocked by the importation of XDR TB into their country should be aware that their economic decisions have fueled, if not rendered inevitable, this drug-resistant pathogen’s emergence. In a large economic analysis of TB incidence, prevalence and mortality, it was found that even drug access was not as large a determinant of TB incidence and outcomes as were International Monetary Fund programs [34]. These programs, funded in part by
In the case of XDR TB, we have hope. Improving the standards of care is an accessible strategy; if
Sanjay Basu is at the Yale University School of Medicine. http://omega.med.yale.edu/~sb493
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