TUBERCULOSIS (TB) : DEFINITION, SYMPTOMS, CAUSES AND MORE

Tuberculosis, that is more commonly known as TB, is a very serious and contagious infection that usually occurs in the lungs. The causative agent of tuberculosis (TB) is a type of bacteria that is known as Mycobacterium tuberculosis.

This bacteria that causes tuberculosis, that is Mycobacterium tuberculosis, spreads by droplet infection from one person to another ( air borne disease) and hence it is contagious that is it can spread from one person to other person easily.

TB is usually caused in an immunosuppressed patient, that is in a person whose immune system is really weak. People who are suffering from HIV and AIDS are more prone to this kind of disease of the lungs. As in HIV / AIDS, the immune system of the person is completely destroyed and the person is not able to fight back with any of the disease, hence the immune system cannot fight back with the causative agent of this disease, and hence cannot protect the body from it, which eventually leads the body of the person to be affected with this disease.

The treatment of this kind of disease is not very easy. Though various drugs and medications are available for curing this disease, but most of the TB strains have developed resist to most of these drugs and medications over the year. A person has to do a long treatment and course of these medications to get rid of the disease.

STAGES OF TUBERCULOSIS

The stage of tuberculosis helps one know that in which direction the causative agent of TB is heading and how mild or severe is the infection caused by this causative agent. There are basically 4 stages of tuberculosis. They are listed below :

Stage 1

• As this is just the initial stage, in this stage the causative agent of TB, that is Mycobacterium tuberculosis bacilli enters respiratory passage of the person
• The stage 1 actually begins after a week when the person has inhaled the bacilli of the causative agent of TB.
• As the bacilli reaches the air sacs (alveoli) in the lungs, the special cells of the immune system that have a phagocytic function – macrophages picks up these bacilli and attacks them
• The function of macrophage is to destroy any foreign substance that enters in the alveoli of the lungs, as these macrophages reside inside the wall of these alveoli
• If the number of TB bacillus are too large or the macrophage was not strong enough to digest and destroy it, that bacilli reproduce within the macrophage itself leading to further infection in the body

Stage 2

• As the macrophage was not strong enough to destroy and digest the TB bacilli, the infection enters the stage 2 phase
• Stage 2 begins after almost a week of stage 1
• In this stage, the TB bacilli, start reproducing more and more exponentially and as a result such a great number of TB bacilli are formed in the body that can no more further be destroyed by the macrophages.
• The duration of stage 2 is almost a week after the initial infection that occurred in stage 1

Stage 3

• In this stage 3, the TB bacilli does not anymore reproduce exponentially and the rate of reproduction of TB bacilli and the destruction of these TB bacilli by macrophages is almost balanced.
• This is the fate deciding stage of the disease, if in this stage the body is able to produce enough immune cells to destroy all the TB bacilli, then the person’s infection does not go beyond this stage and he or she recovers only after few weeks of this stage
• If the person’s body fails to produce enough amount of immune cells that can fight all the TB bacilli that are present in the body in that stage, then the infection proceeds further
• If the infection proceeds further, then in the lungs of the infected person, he TB bacilli and the macrophages that destroy this bacilli form a complex together that is known as the Ghon focus
• The TB bacilli are protected in this complex by the lung tissue and they can survive for many years in the macrophage in this stage.
• The person who is infected in this stage is not at all contagious
• This is the latent stage

Stage 4

• Usually all the TB bacilli die in the Ghon focus itself after several years of their inactivation, only a few of them (nearly 5 percentage) get re – activated and enter in thus stage 4
• This stage is also known as the active stage
• The TB bacilli that are re – activated now reproduce and multiply very quickly and forms a cavity in the tissue
• The immune system of the body cannot reach this cavity and hence the infection increases further
• In most of the cases the reactivation of TB bacilli does not occur, it just occurs in people whose immune system is suppressed by disease such as HIV / AIDS

SYMPTOMS OF TUBERCULOSIS

The symptoms of TB depend at what stage or infection of the disease the person is at. If the person is at the latent stage of the disease, this means that the bacteria is present in the body but is in inactive form as does not show any symptoms. If the person is in the active stage this means that the bacteria is present in the person’s body in active form and the symptoms can also be seen. There are various symptoms TB that might occur in the person who is infected by the disease. Some of the common symptoms of the disease are listed below :

• Night sweats
• A persistent cough ( which lasts for about 3 weeks or more)
• Cough with phlegm which sometimes may be bloody as well
• Unintended weight loss
• High temperature
• Fatigue and extreme tiredness
• Loss of appetite
• Swelling in the neck
• Pain in chest due to coughing
• Pain while breathing
• Night chills

 

CAUSES OF TUBERCULOSIS

Tuberculosis can happen to any person who comes in contact with the person who is infected by the disease. As this is an air – borne disease so when an infected person sneezes, coughs or speaks, the infection can be transferred easily.

There are various causes that lead to immunocompressed  state of a person and eventually to this infection, some of them are listed below :

• Suppression of immunity due to HIV
• Drug – resistant TB
• Malnutrition, low body weight
• Diabetes
• Certain cancers
• Severe kidney disease

DIAGNOSIS OF TUBERCULOSIS

There are various diagnostic tests that are available for the diagnosis of this infection. Some of them are listed below :

• Physical examination
• Skin test
• Blood tests
• CT scan
• Sputum tests

TREATMENT FOR TUBERCULOSIS

There are a number of treatments that are available for the cure of this infection. Some of them are listed below :

• Drugs like isoniazid, rifampin, etc.
• Linezolid
• Bedaquilline
• Ethambutol
• pyrazinamide