Tuberculosis (TB) (from Latin tuberсulum meaning ‘tubercle’) is an infectious disease caused by Mycobacterium tuberculosis (bacillus Kochii) and in most cases affecting lungs.
Apart from lungs, it may affect bones and joints, urogenital apparatus, lymphatic nodes, eyes, nervous system, alimentary canal, skin as well as other body organs and tissues.
Source of infection:
The key agent of the infection is an individual having pulmonary tuberculosis and releasing mycobacteria from his respiratory passages. Besides, the source of infection may be farm animals, birds, fish as well as foods of animal and plant origin (meat, milk, etc.), contaminated with mycobacteria.
Routes of entry into human body:
- Through respiratory passages (with the drops of infected person’s sputum, with infected dust).
- Through gastrointestinal tract (with contaminated food, milk and meat obtained from infected animals).
- Through injured skin (this risk is typical for anatomic pathologists, laboratory workers, veterinarians).
- Through prenatal route from an infected mother to her fetus.
Peculiar characteristic of tuberculosis progress:
- When infected with Mycobacterium tuberculosis, healthy people do not always develop symptoms and the disease does not always progress as human immune system suppresses activity of the bacteria.
- Tuberculosis progresses when the immune system is weakened and loses its ability to fight Mycobacterium tuberculosis, which leads to reproduction of the bacteria and development of smear-positive tuberculosis.
Risk groups vulnerable to tuberculosis include people living in unsatisfactory social and economic conditions, having chronic diseases and bad habits, namely:
- People who abuse alcohol
- Drug users
- Chronic smokers
- Patients with diabetes mellitus
- Patients with gastric ulcer
- People living with HIV
- Low-income populations
- People having long-term contact with patients having smear-positive form of tuberculosis