Tuberculosis cases in the United States resurged in the late 1980s, after dropping for four decades. Since 1992, the number of cases has been declining, but it is estimated that more than 15,000 people are infected in this country each year, and worldwide between 2 and 3 million die of the disease. Children are among the most vulnerable to the disease, and represent recent infections (whereas adults who get the disease could have had the bacteria laying dormant for many years). Researchers from the Centers for Disease Control and Prevention analyzed the extent of the problem in U.S. children.

What the researchers wanted to know: How many children, and which children, are being infected with tuberculosis?

What they did: The Centers for Disease Control and Prevention has been collecting data on the number and characteristics of TB cases in the United States since 1953 through healthcare centers that report each new case. The researchers took a portion of this data— people younger than 15 who were diagnosed between 1993 and 2001—and analyzed the demographic characteristics.

What they found: Overall, rates of tuberculosis are decreasing in U.S. children, dropping from 1663 cases in 1993 to 931 cases in 2001. However, there are disparities among certain groups of children—Hispanic and black children make up 74 percent of all cases, and children younger than 5 also make up a disproportionately high number of cases. Children born in other countries are more likely to develop TB, and the authors speculate the effect of immigration would be greater if they knew where an infected child's parents were born—you'd expect more TB cases in kids whose parents came from countries where the disease is common. In adults, having HIV or AIDS can often open the door to a TB infection because of the body's weakened immune system. However, only 1 percent of the children in this study had simultaneous HIV and TB infections.

What it means to you: Tuberculosis is still a problem in the United States, especially among groups that traditionally have had the hardest time accessing good health care. TB is largely preventable and curable, especially when caught in its latent stage, and, as the authors point out, efforts are needed to readdress this issue.

Caveats: Childhood TB can be harder to diagnose than adult TB, primarily in young children for whom the popular TB skin test in inappropriate. Also, the incidence of TB may be underreported in the CDC survey. So, both these factors mean that the number of cases may actually be higher than is reported in this study.

Find out more: The Centers for Disease Control and Prevention contains a Division for Tuberculosis Prevention. Their website has updated news and fact sheets: ww.cdc.gov/nchstp/tb/

The TB surveillance studies are published online by that group, going back to 1999.

Read the article: Nelson, L.J., Schneider, E., Wells, C.D., and Moore, M. "Epidemiology of Childhood Tuberculosis in ihe United States, 1993–2001: the Need for Continued Vigilance." Pediatrics. August 2, 2004, Vol. 114, No. 2, pp. 333–341.

Abstract online: http://pediatrics.aappublications.org