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5 Common Causes of Tuberculosis


Tuberculosis affects millions of people every year and is a threat to humankind. It is a dreadful disease caused by the pathogenic bacteria Mycobacterium tuberculosis. This causative agent of tuberculosis proliferates in the walls of the lungs and causes the infection. Several other organs like the kidneys, brain, and spine can also be invaded by this TB causing bacteria, leading to significant health complications. The causative organism of tuberculosis can easily spread from one person to another through the air.

The contagious disease took the lives of over 1.5 million people in 2021 and is found to be the 13th cause of overall infectious disease deaths worldwide. Even though many measures are drawn by governments and the World Health Organization (WHO), the lack of awareness and reluctant attitude are leading causes of TB disease.

This page can help draw your attention to tuberculosis causes and associated symptoms along with available treatment and dealing measures. Read further and gain information on tackling and winning over the life-threatening TB disease.

Spread of Tuberculosis

The spread of tuberculosis starts from the time you inhale the aerosolised particles of the causative agent of tuberculosis. Simultaneously, it starts multiplying in the minute air sacs of your lungs. Some of these TB causing bacteria even enter the bloodstream and reach various body parts. However, your body will only react to these particles after it intervenes in the immune system, which takes around 2 to 8 weeks to happen. After invading our immune system, Mycobacterium tuberculosis stops spreading further.

This is when your immune system starts battling the bacteria, halting its growth. Not every TB disease is the same; the kind varies among individuals. The disease in humans is primarily categorised into two types:

Latent TB Infection

A person who never develops symptoms specific to tuberculosis supposedly has a latent TB infection. In many individuals, the bacteria cannot replicate within a person’s immune system. As a result, the bacteria cannot further the infection; thus, no active disease is seen. This phenomenon is termed latent TB. This condition does not make an individual capable of passing the disease to someone else. However, this does not mean the person requires no treatment. Every tuberculosis patient has to go through a well-planned treatment to avoid further infection.

Active TB Infection

This TB infection leads to several symptoms. Active TB infection is common among people with a compromised immune system. This may be due to some illness or as a result of continuous medications. Mycobacteria can replicate within the immune system of such individuals and infect their system as a whole. Around 50% of the individuals with latent TB infection witness an active infection within 5 years since the invasion making it pivotal to go through a rigorous treatment and be free of any TB disease-causing germs.

Drug-Resistant TB

This is a major threat to building a healthy society. The causes of tuberculosis remain the same, but the strain of the bacteria is different. These strains spread in our bodies just like the drug-susceptible strains do. Over time, these strains have developed resistance to several drugs, making it difficult to treat them with the available sources. This especially happens when:

  • People ignore to complete their course of medication, and as a result, the bacterial strain gets immune to those drugs.
  • In many cases, healthcare providers prescribe inappropriate medications futile to treat tuberculosis.
  • When the drug prescribed is of inferior quality, such a threat can take over.
  • Many a time, the spread of resistant strains can also cause drug-resistant tuberculosis.

Various Drug-Resistant TB

Among resistant TB, there are 3 major classes to define as resistant causes of tuberculosis. Plus, most of the deaths from resistant microbial strains worldwide happen due to tuberculosis variants. Read on to know further about them.

Multidrug-Resistant TB

This is caused by the mycobacterium strain that can resist the most potent drugs for tuberculosis, including rifampin and isoniazid. These are the primary drugs prescribed by physicians to treat even the deadliest of strains. In case a person is diagnosed with MDR TB, they need to consult a TB expert immediately.

Pre-Extensively Drug-Resistant TB

Also known as pre-XDR TB, pre-extensively drug-resistant TB is a variant of MDR TB that is particularly resistant to drugs like fluoroquinolone, isoniazid, and rifampin. With these potent drugs, they are also resistant to capreomycin, amikacin, and kanamycin, the second-line injectable in the case of tuberculosis.

Extensively Drug-Resistant TB

This is the rarest of the resistant types of tuberculosis. In addition to rifampin, fluoroquinolone, and the second-line injectables, it is also resistant to bedaquiline or linezolid. In such cases, doctors are only left with less effective options to treat affected patients.

People at Risk of Tuberculosis

Several factors increase the risk of tuberculosis, and some of the causes of TB disease spread are discussed below.

Compromised Immune System

Our immune system is our body’s saving soldier. When it is weakened, we are prone to various infections that might prove fatal. For the same reason, people with a compromised immune system are at a risk of having tuberculosis.


Poverty and homelessness lead to stays in overcrowded and poorly ventilated places. This helps the TB bacteria to spread and remain suspended in the air. Many people living together means more people are subjected to the infection.


The place where you stay is a key determinant of being susceptible to diseases like tuberculosis. Some areas, like the equatorial belt, have numerous Mycobacterium strains. People here suffer from tuberculosis more than people in the rest of the world because of the climate of their geographical region ideal for the growth of such microbes.

Presence of Life-Threatening Diseases

People with kidney diseases and who have gone through organ transplants may catch infections like tuberculosis at a faster rate than others. People suffering from rheumatoid arthritis, commonly known as Crohn’s disease, go through specialised treatments that make them prone to TB.

Substance abuse

Alcoholics and drug addicts have a weakened defence mechanism. Their immune system is too fragile to protect them from infections, including tuberculosis.

Diagnosis of Tuberculosis to Eradicate the Disease

Several tests have to be performed to know if a person is infected with the tuberculosis causal agent. Besides, other confirmatory tests for detecting the variant are also crucial for designing the right treatment plan.

Preliminary Tuberculosis Tests

TB Skin Test
This test is commonly known as the Mantoux tuberculin skin test (TST). In this test, the physician injects a minimal dose of a fluid called tuberculin, mostly on our arm’s lower part. After the injection, the patient needs to revisit the clinic after 48 to 72 hours to check for any subsequent reaction on the skin.

Positive Results
A Positive result indicates that the person suffers from a tuberculosis infection. It is deduced by the occurrence of a swollen or raised portion in the area where tuberculin was injected.

Negative Results
When the body does not react to the fluid injected, it is considered that they are not infected with tuberculosis-causing bacteria.

TB Blood Test
This test is termed as an interferon gamma release assay (IGRA). It is an alternative to the Mantoux skin test. The blood test associated with finding tuberculosis germs are of two types, QuantiFERON TB and T-SPOT TB.

Positive Results
A positive report shows the presence of the infectious germ of tuberculosis in your body. To further confirm the presence, doctors recommend a chest x-ray.

Negative Results
When no tuberculosis bacteria are found in your blood, it is inferred as a negative result.

Specific Tuberculosis Tests

Test for Pulmonary TB
To assess whether you have pulmonary TB, take a few rounds of tests to confirm. A chest x-ray is suggested to check for any changes in the lung walls, besides a phlegm test to check for the bacterial strain.

Test for Extrapulmonary TB

For detecting extrapulmonary TB, one has to go through a CT scan, an MRI, and a USG in the parts affected by the bacteria besides the preliminary tests. In some cases, endoscopy and laparoscopy are also recommended. To check if the bacteria has invaded the spine and brain, a lumbar puncture is suggested. In this test, a small amount of the cerebrospinal fluid is sampled to check if the brain and spinal cord are infected by the bacteria.

Preventive Measures of Tuberculosis

As we all know, it is better to prevent than suffer and look for a cure; and tuberculosis also can be prevented if certain measures are taken at an early stage of life.

BCG Vaccination

Bacille Calmette Guerin (BCG) is an attenuated (inactive) strain of tuberculosis bacteria. This cocktail is prepared by using a weakened strain of Mycobacterium bovis. This vaccine is 80% effective on individuals for around 15 years. This is especially beneficial for children. However, the effectiveness of this vaccine decreases after we attain the age of 35.

Furthermore, the vaccine is not as effective in equatorial areas because of the presence of numerous mycobacterium strains in these regions.


ow does a person get tuberculosis?

Tuberculosis is spread by the air-borne bacteria Mycobacterium tuberculosis. It is spread through the air from an infected person to others through droplets released while sneezing and coughing.

What are the causes and effects of TB?

The bacterial strain of Mycobacterium tuberculosis is responsible for causing tuberculosis infection. It weakens the immune system by invading the lungs and other body parts like the brain, spinal cord, and kidney.

What is the major cause of tuberculosis?

Tuberculosis is mainly caused due to homelessness, unhygienic living, compromised immune system due to existing health complications like kidney or liver disease, and diabetes. Substance abuse and unprescribed drug abuse are also vital causes of tuberculosis spread.

What is the most common way to get tuberculosis?

When we are in close proximity to a patient of tuberculosis, we are highly susceptible to such infections as they can easily spread through the air and are transferable from person to person.


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About The Author

Dr.William Lewis Aliquam sit amet dignissim ligula, eget sodales orci. Etiam vehicula est ligula, laoreet porttitor diam congue eget. Cras vestibulum id nisl eu luctus. In malesuada tortor magna, vel tincidunt augue fringilla eget. Fusce ac lectus nec tellus malesuada pretium.

MBBS (Bachelor of Medicine & Bachelor of Surgery) Gold Medalist (2009-2015) M.D In General Medicine (2016-2019), CCID (Infectious Diseases)

PG Diploma In Clinical Endocrinology v& Diabetes, Clinical Associate in Non-Invasive Cardiology

Dr.William Lewis Aliquam sit amet dignissim ligula, eget sodales orci. Etiam vehicula est ligula, laoreet porttitor diam congue eget. Cras vestibulum id nisl eu luctus. In malesuada tortor magna, vel tincidunt augue fringilla eget. Fusce ac lectus nec tellus malesuada pretium.

MBBS (Bachelor of Medicine & Bachelor of Surgery) Gold Medalist (2009-2015) M.D In General Medicine (2016-2019), CCID (Infectious Diseases)

PG Diploma In Clinical Endocrinology v& Diabetes, Clinical Associate in Non-Invasive Cardiology

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