Ask Emily

26 01 2012

I’ve just read that there’s a kind of tuberculosis making a comeback that doesn’t respond to any known TB drugs. How does that happen and can anything be done to treat it or stop its spread?

Tuberculosis (TB) is a bacterial infection, usually of the lungs, although it can invade other tissues.

A healthy person may be infected but not show symptoms, but someone with an active infection may have a cough with blood in the sputum, night sweats, weight loss, and fever. The bacteria spread through coughs or sneezes.

As with seemingly all infections we treat with antibiotics, the TB bacterium has evolved to evade the arsenal of medications we throw at it.

While many cases still resolve after the long-term antibiotic treatment required (6 months or more), often people with the infection begin to feel better or get tired of the unpleasant side effects and will cease the therapy.

As with other similar situations with antibiotics, this premature cessation of therapy can give resistant bacteria the upper hand. The outcome is different grades of TB infection, based on the level of resistance. TB that resists most but not all drugs is multidrug-resistant. TB that resists all but drugs of last resort is extensively drug-resistant, and TB that responds to no antibiotics at all is totally drug-resistant (TDR).

That last form of TB strikes fear into the hearts of epidemiologists and public health officials because it is an infectious disease nightmare.

For a series of reasons ranging from an inability of low-resource countries to test for and detect TB to a lapse in treatment adherence because of poor healthcare management and patient follow-up, the most resistant forms of TB often emerge in areas poorly equipped to control it. Thus, when a report surfaced in January 2012 that a research team had identified 12 cases of TDR TB in India, on the heels of 15 identified cases in Iran in 2006, the worldwide response was, essentially, anxiety and fear.

The fear is that if this TDR form of TB gains a stronger foothold in overcrowded conditions where people walk ill and undiagnosed, it would be a plane flight away from toeholds anywhere else in the world. While humanity dealt with incurable and fatal TB for millennia before antibiotics started to fight back in the 1940s, this resurgence at a time when technology can take a disease around the world in a matter of hours adds a whole new dimension to the threat.

There is, of course, already the threat on the ground in India, where one of the cases is a 13-year-old girl and another of the people in the cohort has died from the disease. But lest anyone think that in their comfortable home in the West they are sheltered from threat, the news the day I wrote this contained reports of a student with TB in Fort Wayne, Indiana, which precipitated notification to 100 students who may have come in contact with their classmate. Another student in Westlake, Ohio, also had been diagnosed with TB, precipitating community action to make people aware of symptoms and prevention of spread.

The communities in these cases benefited from a public health surveillance program that moved into action once each diagnosis was made. But in India, the result has led to public health chaos, with officials arguing over whether or not some of the cases truly were TDR TB. That does not change the fact that TDR TB has already been identified in Iran, or the economic and healthcare gaps that will only continue to contribute to the likelihood of its spread.

Do you have a question for Emily? Send it to: pkids@pkids.org

By Emily Willingham

Video courtesy of IBNLive


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26 01 2012
Emily Willingham (@ejwillingham)

More from Emily:

In response to some of the news stories about “totally drug resistant” TB, the World Health Organization (WHO) released a statement that “TDR” has not been clearly defined for TB and that no method is thus far considered reliable for diagnosing it. In addition, data are lacking about the relationship between a finding of drug resistance in vitro and how a patient will respond to treartment. The statement says that “current WHO recommendations advise against the use of these results to guide treatment.” They have provided a link to a frequently asked questions list: http://www.who.int/tb/challenges/mdr/tdrfaqs/en/index.html

Thanks to PKIDs for forwarding this statement to me.

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