Public Health Impact of Targeted Tuberculosis Screening in Public Schools

People born where TB is prevalent are at higher risk of contracting the disease. In Anne Arundel County, Md., where only 3 percent of the population is foreign-born, foreign-born persons comprised 40 percent of active TB cases in 1998.

In 1987, two foreign-born students in the Anne Arundel County public school system contracted active pulmonary TB. Thirty-five school contacts developed latent TB infection (LTBI). Two years later, the county Department of Health, in collaboration with the public school system, instituted a policy of targeted screening, with the tuberculin skin test (TST) of all foreign-born students entering public schools, under the guidelines of the American Academy of Pediatrics, the Advisory Committee for Elimination of Tuberculosis of CDC and the American Thoracic Society.

Students born outside the United States, even American citizens, must show TST documentation before enrolling in school. Those with a history of TB must show documentation of treatment.

In 1999, the county Department of Health reviewed data on students the department had screened from 1993 to 1998 to evaluate the impact of targeted TB screening. In that time period, 706 foreign-born students took TSTs. One hundred sixteen were positive (median age 14) and 590 were negative (median age 10). Physicians evaluated students with positive TSTs, and the students received chest x-rays. Median time between TST readings and x-rays was 26 days. Only one student had active TB. One hundred seven of the 115 candidates eligible for LTBI took isoniazid under parental supervision. Six students refused treatment, and two candidates, contacts of a child with isoniazid-resistant TB, took rifampin. Adherence rate to the treatment was 90 percent.

The authors estimate that without treatment, 11 cases of active TB would have occurred during the lifetimes of those with LTBI. About six to eight cases were averted with isoniazid treatment, assuming an isoniazid efficacy of 69-99 percent in children, the study reports.

Economically, staff salaries and benefits accounted for 85 percent of the intervention cost, an estimated $32,617 for six years. The researchers estimated the potential cost of lifetime disease averted at $98,350, giving a net savings of $65,733. "From the societal long-term perspective," the study reports, "$2 was saved for every $1 invested."

The authors concluded that, "As US rates decline, the treatment of LTBI and the control of imported TB become priorities. Despite its limitations, targeted school screening followed by LTBI treatment can be cost-effective against TB in recent immigrants (< five years). This study offers further support for the recommendations of the American Academy of Pediatrics, the CDC and the American Thoracic Society."

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