Slowdown in TB decline worries experts

WASHINGTON (Reuters) - The rate of tuberculosis among the U.S. population fell more than 3 percent last year, but that is not as fast a decline as before and is worrying, federal health officials said on Thursday.

And more cases of extensive drug-resistant TB are showing up -- a hugely expensive and difficult-to-treat strain, the U.S. Centers for Disease Control and Prevention reported.

The CDC's report on TB in the United States was released alongside a World Health Organization report that showed rates of TB globally are stable, with nearly 9 million new cases in 2005 and 1.6 million deaths.

AIDS has fueled a resurgence of the age-old scourge, and new types that resist almost all current drugs are emerging. Years of intensive therapy are needed to cure these "XDRs," or extensively drug-resistant strains.

The CDC reported 13,767 tuberculosis cases in the United States in 2006, a rate of 4.6 cases per 100,000 population. That is a 3.2 percent decline from the 2005 rate.

But Dr. Kenneth Castro, Assistant Surgeon General and director of the CDC's Division of Tuberculosis Elimination, said this was the slowest rate of decline in 10 years.

"This overall slowing is worrisome because it signals stagnation in our progress in reducing tuberculosis," Castro said.

The average annual decline in the U.S. TB rate slowed from 7.3 percent per year in the 1993-2000 period to 3.8 percent per year in the 2000-2006 period, the CDC said.

Castro told reporters in a conference call that 55 percent of persons reported with tuberculosis in the United States were born outside of the country.

"Most of these persons were probably infected with tuberculosis in the countries of origin and subsequently developed tuberculosis disease once they were in the United States," he added.

"As long as tuberculosis continues to be global problem, we will see it manifesting in our own midst."

The CDC said it was considering making some changes in screening that is done for people who apply to come to the United States, including adding tests for drug resistance when screening would-be immigrants for TB.

The CDC said 124 cases of multidrug-resistant TB were reported in the United States in 2005, and 17 cases of XDR tuberculosis were reported between 2000 and 2006.

Castro said XDR TB is especially expensive.

"We are finding that on average, hospital costs run about $500,000," he said. "That is half a million dollars per person with XDR TB, not including indirect costs of lost wages, not including outpatient costs of care," he said.

To treat XDR TB requires 18 months to two years of treatment with a mixture of four to six drugs. XDR TB treatment can often require surgery as well as the newest drugs.

Multidrug-resistant TB is resistant to at least two first-line antibiotics. XDR TB is resistant to first-line antibiotics, and to an entire class of antibiotics called fluoroquinolones, as well as to at least one of three injectable drugs.