Latent Tuberculosis Infection Control

Criteria for Determining Infectiousness in TB

Patients with suspected or confirmed active TB are considered infectious if they are coughing or undergoing cough-inducing procedures, have positive AFB sputum smears, or are not on chemotherapy, have just started chemotherapy, or have poor response to chemotherapy, as recommended by the Centers for Disease Control and Prevention 1
Additional factors that indicate infectiousness include laryngeal or extensive pulmonary involvement, cavitary TB on chest radiograph, and pronounced cough, according to the Centers for Disease Control and Prevention 1
Cavitary TB on chest radiograph is also an indicator of infectiousness, as noted by the American Thoracic Society 2

Isolation is only required for patients with suspected or confirmed active pulmonary TB, and patients should be placed in airborne isolation with negative pressure ventilation until they are deemed non-infectious, as recommended by the Infectious Diseases Society of America 3
Patients can be considered non-infectious after they have been on effective anti-TB therapy, shown clinical improvement, and had three consecutive negative sputum AFB smears collected on different days, according to the Centers for Disease Control and Prevention 1

Unnecessarily isolating patients with LTBI wastes resources and causes patient distress, as reported by the World Health Organization 4
Failing to recognize when patients with active TB become non-infectious after starting effective treatment is a common pitfall, as noted by the European Centre for Disease Prevention and Control 5
Not identifying the source case when a child is diagnosed with TB is a critical error, as the source is often a family member, according to the American Academy of Pediatrics 2

Even patients with active TB on effective therapy can be de-isolated once the risk of transmission is reduced to very low levels, as recommended by the International Union Against Tuberculosis and Lung Disease 6