Epidemiology of persistent tuberculosis in DeKalb County, Georgia, 1990-1996

In DeKalb County, Georgia, during 1990 to 1996, tuberculosis incidence rates fluctuated between 15.3 cases/100,000 person-years (PY) and 19.2 cases/100,000 PY. These rates are approximately 1.5 to 2 times higher than those measured for the United States as a whole, and do not reflect the decline observed nationally since 1993. We reviewed DeKalb tuberculosis registry to investigate risk factors for tuberculosis and describe trends of tuberculosis incidence over time.

We compared average annual tuberculosis case counts and incidence rates in DeKalb before and after 1993. We calculated rates of tuberculosis incidence using race, age and sex stratified population estimates from the U.S. Bureau of the Census. We compared these rates for the periods 1990-1992 and 1993-1996 using Poisson regressions.

Between both time periods, tuberculosis case counts decreased by 6% among whites, by 2% among blacks, and increased by 34% among Asians. Despite this large increase in case numbers, tuberculosis incidence rates among Asians only increased by 4%. For all three race groups, tuberculosis incidence almost doubled for those younger than 15 years of age.

Trends of tuberculosis incidence in DeKalb County varied between different population groups. Migration from countries with a high prevalence of tuberculosis accounted for a larger number of foreign-born cases in recent years. However, increasing tuberculosis incidence rates found among the youngest age groups suggest that active transmission of Mycobacterium tuberculosis also took place.