Tuberculosis Basics

Tuberculosis (TB) is caused by *Mycobacterium tuberculosis*, which is inhaled into the alveoli. Alveolar macrophages may contain the bacilli, producing TB infection without active disease, or the organisms may replicate and cause pulmonary TB disease. Approximately 5–10% of infected people develop disease; the risk is greatest during the first 2 years after infection. Latent TB infection and active TB disease are not interchangeable. Latent infection generally has no disease symptoms and does not transmit TB. Active disease may cause tissue damage and transmission. The 2022 Canadian Tuberculosis Standards also recognize that subclinical TB disease can be asymptomatic yet transmissible, so a person who appears well is not automatically non-infectious. The RPN’s clinical contribution is practical and specific: recognize a concerning pattern, apply airborne precautions promptly, carry out ordered assessments and treatment safely, trend response and adverse effects, reinforce adherence, document accurately, and escalate changes through the appropriate team and public-health pathway.