Criteria for latent tuberculosis - both of the following:
(1) no signs or symptoms of tuberculosis AND one or more risk factors (see below)
(2) positive PPD (intermediate strength) irrespective of past BCG use
Risk factors associated with latent tuberculosis:
(1) history of close contact to someone with tuberculosis
(2) Ghon complex or other typical chest radiographic findings for tuberculosis
(3) HIV infection
(4) immunodeficiency or immunosuppressive therapy
(5) diabetes, cirrhosis, alcoholism or other disease that predisposes to reactivation tuberculosis
where:
• Many of the changes seen with tuberculosis on chest X-ray can also occur with histoplasmosis.
• Some of the risk factors allow mycobacteria to persist by interfering with normal host defense.
Possible modifications to criteria:
(1) addition of a history of tuberculosis that was untreated or inadequately treated to the risk factors
(2) addition of the whole blood interferon gamma release test to the positive PPD
(3) addition of histologic evidence of acid fast bacilli in a pathology specimen
