Tuberculosis is not contagious without expulsion of tubercle bacilli through sputum or respiratory secretions, as seen in some secondary forms of tuberculosis. Not all TB is contagious. It usually manifests as multiple cavities in the lungs and small nodular foci on imaging, often discharging sputum or respiratory secretions with Mycobacterium tuberculosis, such as hematogenously disseminated TB, cavernous TB, fibrotic cavernous TB, and caseous pneumonitis that develops worm-like cavities. Some secondary tuberculosis, such as caseous tuberculosis without cavitation or bacteriophage-negative tuberculosis, are not infectious. Therefore, the presence and level of tuberculosis bacteria in the patient’s sputum and respiratory secretions should be used to determine whether tuberculosis is infectious or not. Consult a medical professional for advice.