Tuberc Respir Dis.  2010 Jun;68(6):328-333. 10.4046/trd.2010.68.6.328.

Interferon-gamma Release Assay among Tuberculin Skin Test Positive Students in Korean High Schools

• Park YK
• Lee SH
• Kim SY
• Ryoo SW
• Kim CK
• Kim HJ
• Cho EH
• Yoo BH
• Lee JK
• Ko WJ

• KMID: 1458041
• DOI: http://doi.org/10.4046/trd.2010.68.6.328

Abstract

BACKGROUND
There are several active tuberculosis (TB) cases in Korean high schools each school year. The risk of transmission in schools is extremely high due to the considerable time spent in closed classrooms. We evaluated the control of latent tuberculosis infection in Korean high schools.
METHODS
When a student was identified with active TB, tuberculin skin testing was performed on their classmates and on students in their same school grade. When a student had a positive tuberculin skin tests (TST), they underwent follow-up testing with QuantiFERON-TB Gold In-Tube (QFT). The manufacturer recommended a cut-off of 0.35 IU/mL to determine QFT positivity was applied.
RESULTS
A total of 131 pulmonary tuberculosis (TB) patients were included based on the criteria for screening TB contacts in the National Tuberculosis Control Program. Seventy-five (57.2%) students tested smear positive. TST were performed on 7,109 students who were classmates of, or in the same grade as, a TB patient. Of the contacts, 1,231 students (17.3%) were TST positive and they were screened with QFT. Six hundred-sixty-six (55.0%) of the tested students returned a positive QFT result and the rate of positivity was significantly associated with the increasing size of TST indurations (p<0.0001).
CONCLUSION
The use of QFT resulted in approximately 45% of TST positive students not being given chemoprophylaxis.

Keyword

Interferon-gamma Release Assay; Latent Tuberculosis Infection; Tuberculin Test; Students

MeSH Terms

Chemoprevention
Follow-Up Studies
Humans
Interferon-gamma
Interferon-gamma Release Tests
Latent Tuberculosis
Mass Screening
Skin
Skin Tests
Tuberculin
Tuberculin Test
Tuberculosis
Tuberculosis, Pulmonary
Interferon-gamma
Tuberculin

Figure

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  Figure 1 Number of schools according to the tuberculosis (TB) patients of smear microscopy results.

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  Figure 2 Number of students according to tuberculin skin test induration size (mm).

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  Figure 3 QuantiFERON-TB Gold In-Tube (QFT) positive rate (%) by tuberculin skin test induration size (mm).

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