TB strain resistant to many drugs emerges

A "virtually untreatable" form of tuberculosis is quickly emerging across the globe, according to a federal report Thursday.

The total number of infections by the new strain is relatively small, but researchers fear it will spread rapidly in the TB incubators of Eastern Europe, India and China.

In 2004, the strain accounted for 11 percent of all drug-resistant TB cases in industrialized countries, up from 3 percent in 2000. "The time to act is now to prevent a new pandemic," said Dr. Marcos Espinal, executive secretary of the World Health Organization's (WHO) Stop TB Partnership.

The data on the new TB strain, published in the U.S. Centers for Disease Control and Prevention's Mortality and Morbidity Weekly Report, come at a time the prevalence of the disease in the United States has reached its lowest point since record keeping began in 1953: 4.8 cases per 100,000 people.

That translates to 14,516 cases in 2005, a 3.8 percent decline from the previous year, according to a second study in the report, timed for World TB Day today.

Even that news has its dark side, said Dr. Kenneth Castro, assistant surgeon general and director of the CDC's division of tuberculosis elimination. "This decrease is one of the smallest declines in more than a decade," suggesting efforts to control the infection have reached a plateau, he said Thursday.

The multi-drug-resistant strains began appearing in the 1980s. The term refers to bacteria resistant to the two first-line therapies normally used to treat the disease. The new strain, "extensively drug-resistant TB," is resistant to those two and to at least three of the six classes of drugs used for second-tier therapy.

The normal death rate for patients with TB is 5 to 6 percent. In contrast, the mortality rate is about 20 percent with multi-drug-resistant TB and at least 33 percent with extensively drug-resistant TB, Castro said.