Recall that two different conditions may occur when Mycobacterium tuberculosis bacteria invade the human body:
Active tuberculosis disease and latent tuberculosis infection.
In active TB disease: Infection occurs when an individual inhales droplet nuclei containing M. tuberculosis bacteria. The bacteria reside intracellularly, within the macrophages. The immune system is unable to keep the bacteria in check. Alveolar macrophages destroy most, but some may multiply intracellularly and are released – alive, and resulting in uncontrolled spread – thus causing active disease.
Symptoms: Unexplained weight loss, loss of appetite, night sweats, fever, fatigue, chills, coughing for >3 weeks, hemoptysis (coughing up blood), chest pain.
Lab and radiology results: Positive TB skin or blood test, may have abnormal chest x-ray, may have positive (sputum) acid-fast bacilli (AFB) smear or culture.
