Delayed tuberculin reactivity in persons of Indochinese origin: implications for preventive therapy

UMMS Affiliation

Department of Quantitative Health Sciences

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Adult; Aged; Cross-Sectional Studies; Female; Humans; Hypersensitivity, Delayed; Lymphocyte Activation; Male; Middle Aged; Radiography, Thoracic; Refugees; Risk Factors; *Tuberculin Test; Tuberculosis; Vietnam


Bioinformatics | Biostatistics | Epidemiology | Health Services Research


OBJECTIVES: To 1) study a variant delayed reaction to tuberculin testing as a way to enhance screening for tuberculosis among high-risk persons and 2) correlate the delayed reaction with lymphocyte blastogenesis.

DESIGN: Cross-sectional study.

SETTING: 2 public health department clinics in North Carolina. Participants: 121 adults who had recently emigrated from Vietnam to North Carolina and who were ethnic Vietnamese and ethnic Dega, a minority population group from the central highlands region of Vietnam.

MEASUREMENTS: Medical history, physical examination, laboratory evaluation, and standard purified protein derivative (PPD) testing (Mantoux method). Skin test results were read at 72 hours and again at 6 days. Variant reactivity was defined as induration of less than 10 mm at 72 hours that, when reassessed at 6 days, had increased in size to 10 mm or greater. Persons with negative (n=54) and variant (n=32) PPD results also had booster testing at 10 to 12 weeks. Serum samples were obtained from 57 participants for lymphocyte blastogenesis studies.

RESULTS: 26% of participants had variant tuberculin reactivity. Variant reactivity was strongly associated with booster positivity: Sixty-five percent of persons with variant PPD results had booster positivity compared with 16% of persons with negative PPD results (P<0.001). The lymphocyte blastogenesis response of persons with variant PPD results was between the response of persons with negative PPD results and that of persons with positive PPD results.

CONCLUSION: Variant reactivity in this high-risk group was a predictor of booster positivity. Together with the blastogenic response pattern, this association strongly suggests that variant reactivity has a high positive predictive value for tuberculous infection. Clinicians should incorporate these findings into their approach for choosing candidates for preventive therapy.


Ann Intern Med. 1996 May 1;124(9):779-84.

Journal/Book/Conference Title

Annals of internal medicine

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