An induration of 5 or more millimeters is considered positive for

•HIV-infected persons

•Recent contacts of persons with infectious TB

•People who have fibrotic changes on a chest radiograph

•Patients with organ transplants and other immunosuppressed patients (including patients taking a prolonged course of oral or intravenous corticosteroids or TNF-a antagonists)

An induration of 10 or more millimeters is considered positive for

•People who have come to the United States within the last 5 years from areas of the world where TB is common (for example, Asia, Africa, Eastern Europe, Russia, or Latin America)

•Injection drug users

•Mycobacteriology lab workers

•People who live or work in high-risk congregate settings

•People with certain medical conditions that place them at high risk for TB (silicosis, diabetes mellitus, severe kidney disease, certain types of cancer, and certain intestinal conditions)

•Children younger than 5 years of age

•Infants, children, and adolescents exposed to adults in high-risk categories

An induration of 15 or more millimeters is considered positive for

•People with no known risk factors for TB