Tuberculosis: Forgotten but not gone

It’s World TB Day: 129 years ago today, Robert Koch announced the identification of the tuberculosis bacillus. It must have looked, back then, as though solving TB — effectively the AIDS of the 19th century, the disease that took leading artists and writers in the prime of their creative lives and inspired novels, poems and operas of loss — was tantalizingly close at hand.

But not. In 2011, the World Health Organization reports, tuberculosis is stubbornly persisting, and the twin problems of multidrug-resistant and extensively drug resistant TB — MDR and XDR — are growing worse.

MDR-TB is resistant to the two drugs that are taken in combination to quell the infection; XDR-TB is resistant to those two and to most of the next-best rank as well. At the best of times, TB treatment is difficult, requiring that a patient take the drug regimen faithfully and accurately for 6 months. In resistant cases, the regimens can take two years or longer. The drugs have unpleasant side effects that make it difficult for patients to stick with them  without monitoring and persuasion. But if patients don’t keep taking them — mostly pills, some injectables — the disease persists, and the person remains infectious and can pass the disease along.

Every year, according to the WHO report, more than 3 percent of all TB cases are MDR, the equivalent of about 440,000 cases per year; every year, there are 150,000 MDR deaths. Every year, there are 25,000 cases of XDR; 69 countries, including the United States, have had at least one detected case. Those may seem like small numbers, compared with the full burden of the TB epidemic: 9.4 million just in 2009 and  1.7 million deaths. But if resistant TB cannot be slowed, it will become an ever-larger portion of the epidemic as a whole.

Detection is key to getting patients the right treatment and monitoring, but it is a phenomenal challenge: Only two-thirds of countries with resistant TB epidemics have the lab capacity to detect the resistant strains. Even fewer have the ability to treat patients adequately: Currently, only one MDR patient out of every 10 even gets into treatment. When they do, cure (and protection of others) is not guaranteed. Cure rates range from 82 percent of patients down to 25 percent.

If those percentages cannot be improved, the WHO predicts there will be 2 million resistant TB cases in just 4 years, by 2015.

It’s hard to know what to say in the face of an epidemic so huge, old and stubborn. The Financial Times has a good analysis of what is needed next.

Update: Sarah Boseley of the Guardian covers the TB situation in Europe. The CDC announces that TB in the US has declined to a record-setting low. And on Twitter, Thomas Goetz flags a fascinating Harvard collection on tuberculosis history.



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