Tuberculosis: Causes, Types, Mechanism and Clinical Indications of Tuberculosis

Definition of Tuberculosis:

It can be defined as a chronic,communicable and granulomatous disease which is caused by Mycobacterium tuberculosis.It usually affects the lungs but may involve any organ or tissue of the body.It is one of the short articles on health.

How infection spreads:

There are three common ways of spreading the infection.

1-Direct droplet spread:

It spreads from person to person by inhalation of air born bacilli that have been coughed or sneezed into the atmosphere.

2-Indirect spread:

This spreads through clothing,dishes and other daily use articles.

3-Via ingested milk:

Ingestion of contaminated milk may spread the infection.This results in intestine and oropharyngial tuberculosis.

Cause of the disease:

It is one of the short articles on health.

There are two strains of Mycobacterium tuberculosis which cause the Pulmonary tuberculosis.

a)Mycobacterium tuberculosis hominis:

Most common strain of the bacteria which affects humans only not the animals.

b)Mycobacterium tuberculosis bovine:

Mostly dairy animals are affected but human may be affected when use contaminated milk.

Factors:

It is one of the short articles on health.

1-Environmental factors;

Environmental factors include the Poverty,overcrowding,unhygienic conditions.

2-Pathological factors:

These include diabetes mellitus,chronic lungs disease, Hodgkin lymphoma,malnutrition and alcoholism.

Mechanism of its development:

The harmful effects of Mycobacterium tuberculosis are not due to any endo-toxins.It due to tissue destruction by the host immune response.Cell mediated immunity or Type4 hypersensitivity develops and T-lymphocytes and activated macrophages and their products are accumulated.It is important to note that all infected individuals do not develop tissue damage.Only 5% of the infected persons develop active disease.The organisms may remain dormant for many years and may be for the whole life of the patient.In later life of the individual the infection may be re-activated to produce the disease.

Types of tuberculosis:

It is one of the short articles on health.

1-Primary tuberculosis:

It is the form of disease that develops in a previously unexposed and non-sensitized individuals.

2-secondary tuberculosis:

It results from reactivation of the dormant primary infection in previously sensitized host.

Clinical presentation of pulmonary tuberculosis:It is one of the short articles on health.

a)Chronic cough with hemoptysis

b)weight loss

c)unresolved pneumonia

d)Exudative pleural effusion

e)Pneumothorax