Tuberculosis Overview and Disease Mechanism

Tuberculosis or ‘TB’ is a very common and dangerous communicable infectious disease found in all parts of the world especially in developing countries like India. Tuberculosis is a bacterial disease caused by a microorganism called Mycobacterium tuberculosis. This tuberculosis-causing bacteria is a non-motile, intracellular parasite and actually belongs to the subgroup Actinomycetes (also called filamentous bacteria ).

The cause behind tuberculosis was discovered by Robert Koch and thus the disease is also known as Koch’s disease. He was awarded the Nobel prize for this in 1905. According to a study conducted by WHO, in 2020, India had the highest count of affected individuals among 30 high TB burden countries that accounts for 86% of TB cases. This is the reason why we must be aware of this disease. 

(Image will be uploaded soon)

Types of Tuberculosis

This disease can be broadly categorized into two groups as follows-

• Active TB - This is actually referred to as tuberculosis disease. The bacteria actively divide in the body of the host and symptoms become visible in the case of active Tuberculosis.

• Latent TB - This type of TB is asymptomatic. Due to the strong immune system of the body, the bacteria are not able to flourish in the body of the host.

Some types of Active TB are given below-

1. Pulmonary Tuberculosis- This kind of tuberculosis affects the lungs.

2. Extrapulmonary Tuberculosis- When tuberculosis not only affects the lungs but spreads to different parts of the body from the lungs, it is called extrapulmonary tuberculosis. This type of TB is very rare and can be found in people with low immunity.

3. Skeletal TB- Skeletal tuberculosis, also known as bone tuberculosis, is tuberculosis that spreads from your lungs or lymph nodes to your bones. Any of your bones, including your spine and joints, can be affected. 

4. Miliary TB- Miliary tuberculosis is a type of tuberculosis that spreads throughout the body, affecting one or more organs. The lungs, bone marrow, and liver are frequently affected by this kind of tuberculosis. However, it has the potential to spread to other regions of the body, such as the spinal cord, brain, and heart.

5. Genitourinary TB- The second most frequent type of tuberculosis is genitourinary TB. The kidneys are the most common site, however, it can infect any region of the genitals or urinary tract. It commonly spreads from the lungs to the surrounding area via the blood or lymph nodes. Intercourse can also spread genitourinary TB, however, this is uncommon.

6. Liver TB- Hepatic TB is another name for liver TB. When tuberculosis (TB) attacks the liver, this happens. It is responsible for less than 1% of all tuberculosis infections. The lungs, gastrointestinal system, lymph nodes, and portal vein can all transfer TB to the liver.

7. Meningitis TB- TB meningitis, also known as meningeal tuberculosis, is a kind of tuberculosis that affects the membranes that protect the brain and spinal cord. From the lungs or the bloodstream, tuberculosis can travel to the meninges. TB meningitis, unlike other varieties of meningitis, usually takes a long time to develop.

8. Peritonitis TB- TB peritonitis is a type of tuberculosis that involves inflammation of the peritoneum, a layer of tissue that covers the inside of your abdomen and most of its organs.

9. Pericarditis TB- When tuberculosis spreads to the pericardium, it is known as TB pericarditis. This is made up of two thin layers of tissue separated by fluid that surrounds and supports the heart.

10. Cutaneous TB- Cutaneous tuberculosis is a type of tuberculosis that affects the skin. Even in places where tuberculosis is common, it is extremely rare.

Tuberculosis Symptoms 

Tuberculosis is a chronic disease. It gradually starts and remains for a long time. Active pulmonary Tuberculosis is symptomatic and infectious. It shows the following symptoms-

• Persistent cough for 3-4 weeks

• Continuous fever

• Chest pain

• Blood in the cough of the patient

• Weight loss

• Loss of appetite

• Increase of hoarseness in voice

• Fatigue 

Tuberculosis Diagnosis 

As the symptoms appear, one must go to the doctor for confirmation of the disease. If left untreated, tuberculosis can even lead to death. Early detection of the disease plays a crucial role in saving the life of the patient. There are various diagnostic methods that are used to detect tuberculosis.

Some of them famous diagnoses are mentioned below:

• Tuberculin Test- This test detects pulmonary tuberculosis. Tuberculin is a toxin that is released by the bacteria Mycobacterium tuberculosis. The test used is the Mantoux Skin test. In this test, a small amount of old tuberculin is injected in the superficial layers of the skin. If in 72 hours some redness, scar, and swelling are found in the area of the application then the test is positive and the person is stated to be suffering from tuberculosis.

Extrapulmonary Tuberculosis is not common and affects organs other than the lungs like the brain, spinal cord, joints, bones, intestine, kidneys, etc. To diagnose this disease a sample of bacteria is taken from the lesions caused or from the secretions of these lesions.

• Sputum Test -Testing the sputum of the patient for the presence of causal bacteria can also reveal the status of the disease.

• X-Ray -Taking the x-ray of the chest also helps in the diagnosis of the disease.

Tuberculosis Treatment 

Treatment of tuberculosis is very important.  Untreated TB can be lethal.

• Antitubercular drugs like INH, Rifampicin are given to the patients for a time period of 4-6 months. The success of the treatment majorly depends upon the patient.

• If one discontinues the treatment before its completion the disease can return and can become untreatable. The tracing of the progress of the patient during the course of treatment is also very necessary.

• Isolating the patient is also a part of the treatment.

DOTS

Directly Observed Treatment Short-Course (DOTS) is a five-point strategy widely accepted and has been proved successful in treating TB. DOTS if applied effectively can prevent multi-drug resistance in the patient.

This treatment involves providing good drugs(medicines) to the patient on a regular basis using microscopy, observing the progress of the patient, and keeping track of it. This treatment course is continued for 6 months.

DOTS have been found effective in HIV patients also who are more susceptible to infections.

Conclusion

Tuberculosis is a chronic disease that affects many people throughout the world, especially in third-world countries. Focus on the different types of this disease and how it is treated.