TB Challenge: Partnering to Eliminate TB in African Americans
Pediatric TB Epidemiology: Preventing Cases and Evaluating Health Systems
John Jereb, MD, Medical Officer, CDC/DTB
What does pediatric tuberculosis (TB) tell us about TB control? Pediatric TB cases in a community provide a sensitive indicator of the trends, the successes, or the short-comings of the healthcare and public health systems. A re-view of the epidemiologic trends of pediatric TB reveals whether or not TB transmission is being prevented; exploration of each pediatric case opens the way to learning about missed opportunities to prevent transmission by diagnosing TB in adults sooner, to find all high-priority contacts promptly, and to treat latent infections before TB disease develops.
By the fact of their young age, children who have TB must have been recently infected with Mycobacterium tuberculosis. Pediatric cases rarely develop into contagious forms of disease; therefore, child-to-child transmission is rare. This is unlike the timeline and contagiousness of TB in adults, who could have been infected a generation earlier, and who are more likely to become contagious. Children who are younger than age 5 years are more likely than adults to have disease instead of just latent infection. When preschool-age children have TB, the cases most often point to prolonged exposures in the household, the extended family, or the close community, for example, at a child day-care center. Brief exposures to strangers who have TB in the wider community are not likely to cause cases.
Pediatric cases always represent recently missed opportunities and gaps in healthcare services or public health systems. If every adult who has TB could be diagnosed before the disease became contagious, or if contact investigations were comprehensive and early enough, all infect-ions and disease in children could be avoided. When children do have advanced TB disease, it shows that contact investigations were incomplete or that cases in adults were discovered too late to prevent transmission and subsequent progression of the infections in contacts. These factors might be different for immigrant children who have TB in the United States, because infection could have happened overseas.
Pediatric TB, defined here as TB in children younger than age 15 years, is uncommon in the United States: 779 pediatric cases out of 13,299 total TB cases in 2007. Nationally the numbers and the rates of reported pediatric TB cases have been decreasing in parallel with the numbers and the rates for older groups.
Dividing pediatric TB cases into the patients' racial groups reveals disparities that are more extreme than those for adults. When non-Hispanic white children are the reference group, the rates for children in the other racial groups are about 15 times greater.
The rates are greatest for Asian and Hispanic children, but these two groups have large fractions of cases among foreign-born children.
On average, the rates for foreign-born children are about 10 times greater than those for US-born children. Until recently, almost all non-Hispanic black children who had TB in the United States were born here. New immigration trends appear to be increasing the fraction of foreign-born children among non-Hispanic black children who have TB.
Children are, in effect, accidental victims when adults have TB. If all adult cases could be prevented, or caught early enough to avoid transmission, then all pediatric cases would be averted. When this cannot be achieved, intensive contact investigations are the next safeguard. Children are listed as high-priority contacts in the recommendations from the National TB Controllers Association (NTCA) and CDC: Guidelines for the Investigation of Contacts of Persons with Infectious Tuberculosis. Most pediatric cases in the United States are found during contact investigations. In very young children, TB is highly lethal unless it is treated in its early stages. Deaths associated with TB are reported for less than 1% of pediatric cases, although the rate of deaths is 2% for children younger than age 1 year. Any death of a child because of TB should provoke an intensive review of missed opportunities.
Tuberculin skin testing is not recommended for all children. The Academy of Pediatrics recommends screening all children with a questionnaire reviewing the indicators of exposure, for example, birth or residence in a country with a large TB incidence rate. Only children who have indicators of exposure should be tested. For children born in the United States, the risks usually depend on the TB risks of adults who share the household. The testing of children who are unlikely to be infected wastes resources and contributes to false-positive results, which cause unintended consequences such as expense, psychological stress, unnecessary treatment, and adverse effects of treatment.