ucsdhealthsciences:

Trouble with a capital TB

The history of tuberculosis is long and terrible. The lung disease, caused by Mycobacterium tuberculosis, is highly infectious. The bacterium is easily spread within aerosolized droplets produced by the coughing, sneezing, laughing or talking of carriers.

One-third of the world’s population is thought to have been infected with M. tuberculosis (pictured above). New infections occur at a rate of about one per second. In 2010, there were an estimated 8.8 million new cases, mostly in developing countries, with more than 1.5 associated deaths.

Antibiotics have been the primary treatment of TB, but increasingly, strains of drug-resistant M. tuberculosis are making that fight more difficult. Indeed, cases of multidrug-resistant TB are on the rise. A new study in the journal The Lancet underscores the seriousness of the threat.

The study, led by researchers at the Centers for Disease Control and Prevention  examined the effectiveness of second-line drugs in patients with TB who were already resistant to primary drugs like rifampin and isoniazid.

Currently, public health officials assume that roughly 5 percent of TB cases are resistant to the most common antibiotic treatments. The latest CDC report suggests that may be a gross underestimation, especially in second- and third-world countries. In Minsk, Belarus, for example, CDC scientists say almost half of newly reported tuberculosis infections last year were resistant to common drugs.

The growing TB crisis is fueled by its easier spread in places already ravaged by the concurrent HIV epidemic, which has left millions of people with compromised immune systems unable to fend of a TB infection.