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Tuberculosis (TB): Types, Symptoms & Treatment

The information you are going to get from this Article are:
1. What is TB and what causes it?
2. What is acid-fast staining?
3. Anatomy and Function of Lungs
4. Types of TB
5. Symptoms
6. Diagnosis
7. Treatment


Tuberculosis (TB) is a contagious (spreading) and life-threatening infectious disease caused by bacteria known as Mycobacterium tuberculosis. It is an acid-fast and aerobic (aerobic organism needs oxygen for its growth) bacteria. Most of the time this bacteria affects the lungs and in this case, it is called pulmonary TB. However, in some cases, this bacteria can also spread to other parts of the body and is called extrapulmonary TB.

Acid-Fast Staining

It is a lab test that is done to identify the presence of bacteria in the smear (spot). The doctor will collect the sputum (mucous) of the patient and send it to the lab for a test. After the process of staining if the sputum of the patient is infected with the bacteria then it will stain red.

Anatomy & Function of the Lungs

There is a pair of air-filled, spongy organs present on each side of the thorax (chest) called lungs. Lungs are the organs that play an important role in the respiratory system. The right lung is wider than the left lung because the left lung has a cardiac notch (space) on its surface. The cardiac notch is the area of the heart. The right lung is also shorter than the left because the liver is present on the right side of the body having its position just beneath the right lung. The tissue that covers, protects, and moisture the lungs are called the pleura. The right lung has three lobes as compared to the left which has two lobes. The parts which separate the lobes of the lungs are called fissures. The right lung has an oblique (tilted) fissure which separates the middle and lower lobes and a horizontal fissure that separates the upper and middle lobes. The left lung has an oblique fissure that separates the upper and lower lobes. The mediastinum is the area that is present between the lungs. It consists of the trachea, heart, esophagus, etc. The trachea (windpipe) enters both the lungs when it divides into the left and right primary bronchi. The primary bronchi then divide into secondary bronchi which further divide into bronchioles. At the terminal of the bronchioles present the tiny air sacs called alveoli. when we inhaled the air from the mouth or nose, it travels from the pharynx and larynx (voice box) to the trachea (windpipe). The air then enters the lungs through the bronchi. Then traveling from the bronchioles enters into the alveoli. Here the exchange of gases occurs. The oxygen from the outside air enters into the blood and carbon dioxide is removed from the blood when the person breathed out.


There are two types of TB latent or inactive state and active state. The majority of the cases are latent which is not harmful and only a few of them progress to an active state.

1. Latent TB

The mycobacteria are transmitted by the air and when a person inhaled the air the bacteria enters the body. Inside the body, the mycobacteria attack the lungs and move into the alveoli. This bacterial attack triggers the immune response. The macrophages (type of white blood cell) attack and ingest the bacteria but cannot kill them due to some virulence factors of bacteria. The macrophages continue ingesting the bacteria and also attract other immune cells to surround the macrophages that already ingest the bacteria. Together they form a mass called a granuloma. The bacteria inside the granuloma survive and remain dormant (motionless) but the macrophages having bacteria inside them begin to die and cause caseous (it means the conversion of damaged tissues into the cheese-like form) granuloma. This is called latent state. Most of the patients infected with TB don’t even know they are infected because this state does not show any symptoms and also it cannot spread. Generally, TB remains in the latent state for many years or even for a lifetime.

2. Active TB

This condition occurs when the immune system of the latent TB patient weakens. The factors that may cause weakness of the immune system are HIV, Diabetes, some medications, not treating latent TB, etc. The weak immune system is unable to avoid the bacteria from growing. In this way, the bacteria begin to spread and destroy lung tissues. In some patients, the bacteria spread into the bloodstream and affect other organs such as the liver, kidney, brain, etc. This serious form of TB is called miliary TB. The patient with active TB has symptoms and can spread the bacteria by coughing, laughing, speaking, etc.


Coughing out blood, fever, chills, night sweats, cough that is last for three weeks, etc.


If anyone wants to know whether one is having TB or not then there are two tests available that are TB blood test and TB skin test.


The medications that are used to treat TB are rifampicin, isoniazid, ethambutol, etc. Don’t use any of these medicines without asking your doctor. Your doctor will tell you which medicine you will take and for how long.

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