Table 2.

Characteristics or clinical features of persons who should receive treatment for LTBI corresponding to degree of induration on skin testing.

Diameter of induration	Characteristics or clinical features
5 mm	HIV infection
	Recent close contact with a person with active TB*
	Fibrotic changes on chest radiograph consistent with prior TB
	Organ transplant recipients and other immunocompromising conditions requiring the equivalent of 15 mg/day of prednisone for 1 month
10 mm	Foreign-born from high prevalence regions such as Asia, Africa and Latin America and immigrating to this country within the last 5 years
	Intravenous drug and alcohol abuse
	Residing or working in a high risk congregate setting (e.g., correctional facility, nursing home, homeless shelter, hospital, etc.)
	Employed in a mycobacteriology lab
	Medical conditions that places persons at high risk
	Less than 4 years of age or <18 years of age and exposed to adults in high risk categories
15 mm	No known risk factors for TB

*Recent close contact is defined as at least 12 hours of contact with a person with infectious TB. Persons who have had an initial negative skin test reaction after contact with a person with active TB should receive treatment for LTBI and should be retested 10 to 12 weeks after exposure. If the skin test is again negative (≤5 mm) and the person has been removed from the source of exposure, treatment can be discontinued. Persons with HIV or other immunocompromising conditions should be given treatment regardless of skin test results if they have come in contact with persons with active TB. LTBI, latent tuberculosis infection; TB, tuberculosis