- An acute or chronic infection caused by Mycobacterium tuberculosis
- An acid-fast aerobic bacterium is characterized by pulmonary infiltrates, formation of granulomas with caseation, fibrosis, and cavitation
- Drug resistant TB or atypical Mycobacterial disease
Incubation Period
4-8weeks
Mode of Transmission
- Inhalation
- Ingestion of inoculation of droplet nuclei, spread through respiratory route.
- Swallowing infected sputum may lead to laryngeal. Oropharyngeal, and intestinal tuberculosis
Schematic Diagram
Inhaled Mycobacterium Tuberculosis
↓
Organism multiply-survive URT
↓
Spread through the body: Alveoli (established infection)
↓
Lymphatic channels carry them to regional lymphnodes
Circulatory system transport them to distant tissues and
organs
↓
The organism prefers body tissues with high oxygen
concentration: upper lungs and kidneys
↓
The immune system attacks
↓
Macrophages engulf the organism
↓
Macrophages surround them and wall them off in tiny, hard
capsules
(Tb organism can reside in these tubercles in dormant stage
indefinitely)
↓
Immune system weakens
↓
Infection develops into active TB
(Tb reactivation)
↓
TB organism multiply stimulating the immune system
↓
Activate the Cytotixic lymphocyte macrophages
↓
Emission of toxins that liquefy and destroy lung tissue
↓
Immune response results to formation of cavities
