The tuberculosis (TB) infection rate in the United States fell to a record low last year, but the relatively small decline raised fears that the nation was falling behind in its battle to eliminate the disease.

A total of 14,511 active TB infections, or 4.9 cases per 100,000 people, were reported to U.S. authorities in 2004, according to data published on Thursday by the Centers for Disease Control and Prevention.

That compared with 14,858 cases and a rate of 5.1 cases per 100,000 in 2003.

The rate last year was the lowest since national reporting of the disease began 52 years ago, but the rates of decline in the past two years - 3.3 percent in 2004 and 2.3 percent in 2003 - were the smallest since 1993, the CDC said.

TB rates fell an average 6.6 percent between 1993 and 2002.

“It might suggest that there is a slowing in our progress to eliminate TB in the United States,” said Lori Armstrong, an epidemiologist in the CDC’s division of tuberculosis elimination.

Once a leading killer, tuberculosis waned in the United States after the AIDS epidemic had peaked in the early 1990s. AIDS attacks the immune system and renders the body unable to fight opportunistic infections such as TB.

But U.S. efforts to eliminate TB, spread by coughing and close personal contact and usually cured with a long course of antibiotics, have been stymied in part by higher rates of the disease in other countries, including neighboring Mexico.

An estimated eight million new TB cases are reported worldwide every year, leading to 2 million deaths.

Foreign-born residents accounted for almost 54 percent of the TB cases in the United States in 2004, according to the CDC report. Hispanics, for the first time, had the largest share of overall cases due to their growing population.

Hispanics and blacks were about 8 times more likely than whites to have TB last year. Asians had a rate 20 times that of whites.

The CDC said it was working to improve screening of immigrants and refugees overseas, test recent arrivals from countries with high TB rates and coordinate with authorities fighting the disease along the U.S.-Mexican border.