Fear-Resistance: How Worried Should We Be about "Totally Drug-Resistant" Tuberculosis?

[xchrom]

http://www.scientificamerican.com/article.cfm?id=fear-resistance-how-worried-should

A few weeks ago a clinic in Mumbai claimed to have identified a dozen patients with a strain of tuberculosis (TB) resistant to all known treatments. TB is a highly contagious lung infection that kills about 1.5 million people each year worldwide, according to the World Health Organization (WHO), so the development of a totally untreatable form of the disease would be cause for alarm. "It conveys that there is no hope, that not a single drug works," says Madhukar Pai, a tuberculosis researcher at McGill University in Montreal.

Fortunately, it does not appear that the Mumbai cases are completely untreatable. After evaluating the cases last week, India's Ministry of Health and Family Welfare reported that the patients actually had "extensively drug-resistant" tuberculosis, a form of the disease that is difficult to treat, but not incurable. Although three of the 12 patients have died, the other nine are reportedly being treated with antibiotics used to treat extensively drug-resistant TB, such as clofazimine and rifabutin.

Still, the case has prompted WHO to schedule a meeting in March to discuss the merits of creating a new "totally drug-resistant” category of tuberculosis. Most likely, "extensively drug-resistant," or XDR, will remain the top level of tuberculosis threat. For one thing, current laboratory tests for determining drug-resistant TB are not reliable enough to rule out all TB drugs conclusively, particularly three of the six classes of second-line drugs. "The tests aren't highly reproducible," says Peter Cegielski, head of the U.S. Centers for Disease Control and Prevention's drug-resistant TB program. "You can even get different results from the same patient specimen."

WHO cannot designate a new disease category without clear, quantifiable diagnostic criteria. For example, XDR-TB is defined as tuberculosis that is resistant to the main first-line TB drugs—rifampin and isoniazid—and to two or more of the second-line drugs for which there are reliable susceptibility tests.

[bemildred]

1. Well, say there are 7 billion of us today, then

7 billion divided by 1.5 million means your chances of getting killed by TB any particular year is 1 in 4,667, or about .00021, or about two hundredths of one percent.

Just playing with their numbers to derive a guess at an answer to the question in the subject line.

Worth considering that the vast majority of those dead people are likely from the "undeveloped" world.

I've already had TB try to kill me once, so I must be safe now.