But it's a potential public health catastrophe with the new strain called XDR-TB, for extensively drug resistant tuberculosis.

NPR: TB Traveler Exposes Diagnosis Problems

Treatment options for XDR-TB are limited and can themselves be toxic.

WSJ: Dangerous TB Patient Nabbed On U.S. Border

And that's why people like Lawrence Gostin are rethinking what public health authorities should do about people with suspected XDR-TB in the weeks before the diagnosis is in.

NPR: TB Traveler Exposes Diagnosis Problems

XDR-TB is a particularly dangerous form of the disease that is resistant not only to the two most potent TB drugs, but also a handful of second-line drugs.

WSJ: Dangerous TB Patient Nabbed On U.S. Border

But experts agree the number of XDR-TB cases is growing.

NPR: TB Traveler Exposes Diagnosis Problems

For confirmed XDR-TB, in which the bacterium is resistant to the most potent first- and second-line TB medicines, the WHO recommends that a proper combination of any medicine left among those available, dictated by knowledge of susceptibility, should be used.

WSJ: The WHO Supports India's Fight Against MDR-TB �� Letters to the Editor