U.S. Tuberculosis Rate at All-Time Low

The U.S. tuberculosis rate in 2005 was the lowest since the federal government began collecting data on TB in 1953, but the number of cases of multi-drug resistant TB, or MDR-TB, increased for the first time in a decade in 2004, CDC said in a report released on Thursday, the Washington Post reports (Brown, Washington Post, 3/24).

There were 14,093 TB cases reported in the U.S. during 2005 -- about 4.8 cases per 100,000 U.S. residents (McNeil, New York Times, 3/24). By comparison, there were 24,000 TB cases reported in 1994 (Washington Post, 3/24).

However, according to the CDC report released on Thursday, the number of U.S. residents with MDR-TB -- which is resistant to first-line antibiotics -- increased 13.3% in 2004 (McKay, Wall Street Journal, 3/24). CDC examined 169,654 cases of TB in the U.S. from 1993 to 2004 and found that 1.6% were MDR-TB and 0.04% were extensively drug resistant, or XDR-TB (Stobbe, AP/Long Island Newsday, 3/23).

Health authorities recently created the XDR-TB category, which includes strains that are resistant not only to first-line antibiotics but "also to at least one of the expensive toxic second-line drugs," the Times reports (New York Times, 3/24).

The percentage of XDR-TB cases in the U.S. rose from 3.9% in the period between 1993 and 1996 to 4.5% in the period between 2001 and 2004 (Washington Post, 3/24). The CDC report said there were 74 cases of XDR-TB in the U.S. between 1993 and 2004, half of which were in foreign-born residents, and found that 33% of the patients died, compared with 25% of MDR-TB patients and less than 5% of patients with regular TB (McKenna, Atlanta Journal-Constitution, 3/24).

A separate CDC and World Health Organization study of 25 TB laboratories on six continents between 2000 and 2004 found that 2% of worldwide TB samples were XDR-TB and that the prevalence of XDR-TB increased from 5% of MDR-TB cases in 2000 to 6.5% of MDR-TB cases in 2004 (Wall Street Journal, 3/24). Twenty percent of worldwide TB cases were MDR-TB (Atlanta Journal-Constitution, 3/24).

Kenneth Castro, assistant surgeon general and director of CDC's division of tuberculosis elimination, said that the increase in XDR-TB cases in the U.S. was
"modest" but added that "it is a movement in the wrong direction" (Washington Post, 3/24). Castro added that the overall decline of TB in the U.S. has slowed and attributed the change to funding cuts for TB-control measures (Wall Street Journal, 3/24).

Henry Blumberg, epidemiologist at Grady Memorial Hospital in Atlanta and professor of medicine at Emory University, said he was "very concerned" about XDR-TB, adding, "It shows that what happens in other parts of the world clearly impacts" the U.S. (Atlanta Journal-Constitution, 3/24).

Marcos Espinal, a WHO official and head of the Global Partnership to Stop TB, said, "Drug-resistant TB is growing, and that should worry us" (Washington Post, 3/24).

NPR's "Morning Edition" on Friday reported on XDRTB. The segment includes comments from Castro and Espinal (Wilson, "Morning Edition," NPR, 3/24). The complete segment is available online in RealPlayer.