Emory Report

January 31, 2000

 Volume 52, No. 19

Atlanta tuberculosis rate 6 times U.S. average

By Holly Korschun

Despite steady declines in tuberculosis rates in the United States since 1992, the TB rate in Atlanta-54.6 cases per 100,000 persons-was more than six times the national average between 1993 and 1997, according to a recent study published in the November 1999 issue of Clinical Infectious Diseases.

Henry Blumberg, associate professor of medicine-infectious disease, along with colleagues from Emory, Grady Health System, the Georgia Department of Human Resources and the Centers for Disease Control and Prevention, examined the epidemiology of TB in Grady patients from 1991 through 1997. They also assessed rates by ZIP code in eight metro Atlanta counties from 1993 through 1997, using state statistics.

Although the total number of culture-confirmed tuberculosis patients at Grady declined by 35.6 percent between 1991 and 1994, the number remained stable between 1994 and 1997, in contrast to a 7 percent annual decrease nationally over the same period. According to the Emory/Grady study, 1,378 patients (197 per year) were diagnosed with tuberculosis at Grady between 1991 and 1997, representing one-fourth of all cases in Georgia.

If Grady were a state, it would have ranked 28th in the number of tuberculosis cases over the seven-year period, with more cases than Oregon and just fewer than Hawaii. National tuberculosis rates declined 26 percent between 1992 and 1997 to a rate of 7.4 per 100,000-the lowest ever reported.

"Our experience at Grady contrasts starkly with nationally declining trends in tuberculosis," Blumberg said. "In 1997, for example, Grady cared for more tuberculosis patients than in 1980, when national tuberculosis rates were 40 percent higher.

"Tuberculosis remains a serious problem in urban areas. These findings indicate a severe need for concentrated efforts and resources in urban areas if tuberculosis control and elimination are to be achieved in the United States," Blumberg said.

More than 38 percent of Grady's TB patients also were HIV-positive. Over time, there was a significant decrease in the proportion of HIV-positive TB patients, corresponding to a time period when highly active antiretroviral therapy was available and greater numbers of patients in the community were treated with directly observed therapy.

"Tuberculosis case rates in inner-city Atlanta, and the proportion of patients with HIV co-infection, are similar to those seen in developing countries," Blumberg said.

Between 1993 and 1997, the annual TB incidence in the eight-county metropolitan Atlanta area was 14.1 cases per 100,000. Inner-city ZIP codes had the highest rates, with rates decreasing with distance from the inner city.

Two inner-city ZIP codes had annual rates greater than 120 cases per 100,000, and eight ZIP codes had annual rates between 47 and 87.5 cases per 100,000. Twenty-three other ZIP codes in urban areas had annual rates greater than 10 per 100,000. The additional 78 metropolitan ZIP codes had annual rates of less than 10 per 100,000.

Drug resistance among Grady's TB patients during the study period was relatively low compared to cities such as New York and Miami, which have had high rates of multidrug-resistant tuberculosis.

Although TB was once regarded as a disease that could be eliminated in the United States, incidence of the disease increased by 20 percent between 1985 and 1992 largely due to HIV and underfunding of the public health structure. Public health interventions, increased funding for TB control efforts, implementation of directly observed therapy and prevention of hospital infections led to the disease's decline in the 1990s and has raised new discussion about the feasibility of the U.S. Public Health Service's goal of eliminating tuberculosis by 2010.

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