What is Tuberculosis ?

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What is the meaning of Tuberculosis (TB)?

Tuberculosis (TB), also known as Koch’s disease, is a highly infectious chronic disease caused by bacteria called Mycobacterium tuberculosis that spreads through contact with an infected person. This disease most commonly affects the lungs (pulmonary tuberculosis), however, other parts of the body such as intestines, bones, meninges (brain covering), lymph glands, etc., can also be affected.

Tuberculosis (TB) is a worldwide public health problem. It is estimated that about 33.3% of the current global population is infected asymptomatically (showing no symptoms) with tuberculosis, of whom only a few develop the clinical disease during their lifetime. Tuberculosis is one of the leading causes of infection-related deaths, with a majority of the new cases and deaths occurring in developing countries. An infectious pulmonary tuberculosis patient can, on average, infect 10-15 people in a year. India is the country with the highest TB burden in the world, and in 2015, India accounted for about one-fourth of the estimated global cases of tuberculosis. More than 80% of tuberculosis cases in India are in the age group of 15-54 years. With the correct diagnosis, treatment, and prevention strategies, tuberculosis is curable. 

Let us tell you more in detail about tuberculosis in this article:

• What is the Cause of Tuberculosis (TB)?
• Types of Tuberculosis (TB)
• Who is most at risk of getting Tuberculosis (TB)?
• Symptoms of Tuberculosis (TB)
• Diagnosis of Tuberculosis (TB)
• Treatment of Tuberculosis (TB)
• Complications of Tuberculosis (TB)
• Prevention of Tuberculosis (TB)

What is the Cause of Tuberculosis (TB)? 

Tuberculosis is caused by a bacterium called Mycobacterium tuberculosis. This disease spreads through direct inhalation of the bacilli present in the air. Sneezing, coughing, and talking release a large number of droplets that contain as many as 3000 infectious particles per cough. The disease spreads most commonly among those who are in close or prolonged contact with an infected person, i.e., a person whose sputum (phlegm) contains a minimum of 10,000 bacilli per ml. Consumption of unpasteurized (unsterilized) milk can lead to intestinal tuberculosis though this is rarely seen now due to pasteurization of milk.

Usually, the inhaled bacilli are prevented from reaching the lungs by the natural defenses of the body. However, factors such as the number of infectious bacteria, age, low immunity, stress, malnutrition, and other coexisting illnesses increase the chance of getting infected by tuberculosis. 

Types of Tuberculosis (TB)

Based on the time of infection and the type of response of the individual, tuberculosis is classified as-

• Primary tuberculosis – It is the initial infection by Mycobacterium that almost exclusively affects the lungs. Primary tuberculosis is mostly seen in children and is generally asymptomatic and less severe. In most cases, primary tuberculosis heals in 2-6 months, while in some cases, a few bacilli may survive in the body and remain latent (inactive). 
• Secondary tuberculosis – It occurs due to the reactivation of the latent (inactive) infection or due to re-infection by Mycobacterium. It is seen both in children as well as adults. In secondary tuberculosis, the infection spreads to other organs and tissues such as the intestine, meninges, skin, etc. This type of tuberculosis is usually symptomatic and more severe as compared to primary tuberculosis.

Who is most at risk of getting Tuberculosis (TB)?

Anyone can contract tuberculosis, but there are certain risk factors that increase the chance of developing tuberculosis. These factors include-

1. Close or prolonged contact with an infected tuberculosis patient
2. Low immunity/weak immune system. It is particularly seen in the following conditions –

• HIV and AIDs ( Know more about- What are the symptoms of STDs )
• Uncontrolled diabetes ( Know more about- What is Diabetes ? )
• Kidney disease 
• Cancer 
• Treatment of cancer such as chemotherapy
• Drugs that suppress the body’s immune system such as steroids.
• Old age

3. Traveling to or staying in an area where tuberculosis is very common such as Asia, Africa, Russia, Latin America, and Eastern Europe.
4. Health care workers and nurses who are treating tuberculosis patients
5. Consumption of alcohol and intravenous drugs that weaken the immune system
6. Smoking 
7. Socio-economic factors such as poverty, overcrowding, inadequate medical facilities, inability to afford medications, etc.

Symptoms of Tuberculosis (TB)

Symptoms of primary tuberculosis that primarily affect the lungs are-

• Chronic cough with sputum ( Know more about- Causes of Whooping cough )
• Cough with blood-stained mucus
• Breathlessness 
• Chest pain ( Know more about- Home remedies for chest pain )
• Fever
• Night sweats
• Weakness
• Loss of weight 
• Loss of appetite

In secondary tuberculosis, the infection spreads to other parts of the body and is known as extrapulmonary tuberculosis. The symptoms of extrapulmonary tuberculosis include-

1. Swollen or pus-filled lymph nodes (Tuberculous lymphadenitis)
2. Fever, headache, stiff neck, vomiting (Tuberculous meningitis)
3. Pain during urination, abdominal pain, blood, and pus in urine (Renal tuberculosis)
4. Abdominal pain, fever, weight loss, vomiting (Intestinal tuberculosis)

Diagnosis of Tuberculosis (TB)

• History taking and physical examination during which the doctor examines the chest for abnormal breath sounds and other signs and symptoms such as swollen lymph nodes, fever, etc.
• Examination of sputum – The added benefit of this method of diagnosis is that it not only confirms whether the patient has tuberculosis or not, but also helps to select the most effective course of treatment.
• Chest X-ray and CT scan 
• Blood tests to check the number of white blood cells and the rate at which red blood cells sediment, known as Erythrocyte Sedimentation Rate (ESR).
• Fine needle aspiration cytology (FNAC), in which cells from enlarged lymph nodes are examined for tuberculosis.
• Molecular methods such as polymerase chain reaction (PCR)
• Tuberculin skin test (Mantoux test) – In this test, a small amount of tuberculoprotein (purified protein derivative) is injected into the arm. The site of injection is examined after 48-72 hours, and the health care worker interprets the reaction to the tuberculoprotein. A positive tuberculin test indicates infection with tuberculosis bacilli, whereas a negative test indicates no infection. 

Treatment of Tuberculosis (TB)

Mycobacterial infections require prolonged treatment. The first line antitubercular drugs are Isoniazid (H), Rifampicin(R), Pyrazinamide (Z), Ethambutol (E), and Streptomycin(S). These drugs are very effective, cheap, less toxic, and routinely used in drug-sensitive cases of tuberculosis.

Newly diagnosed patients are required to take these medications for 6 months, whereas previously treated patients who got re-infected are required to take these medicines for 8 months. It is extremely important to complete the entire treatment as stopping the treatment in between or skipping doses can make the person resistant to these drugs, and hence, these medicines will no longer be effective. 

The treatment of multidrug-resistant tuberculosis (MDR-TB) is complicated and a combination of antibiotics such as fluoroquinolones, macrolides, aminoglycosides are administered for about 24-27 months.

The World Health Organization in 1994 announced a new strategy for the worldwide treatment of tuberculosis known as DOTS- Directly Observed Treatment Short course. An important part of DOTS is that the patient is required to take the medicine in front of the healthcare professional at the DOTS center. It ensures that the treatment is thoroughly followed and prevents the occurrence of drug resistance. India DOTS is the fastest expanding program in the world. ( Know more about- What is Lung transplants? )

Complications of Tuberculosis (TB)

Tuberculosis, if left untreated or poorly treated, can be fatal. Complications of tuberculosis include-

• Drug resistance – It is most commonly seen when diagnosed tuberculosis patients do not complete their treatment course. Multi Drug Resistant (MDR) and Extreme Drug Resistant (XDR) tuberculosis are more complicated to treat, and the treatment continues for a longer period of time.
• Joint pain commonly affecting the hips and knees.
• Meningitis (Inflammation of the coverings of the brain) is commonly seen in children and is usually fatal.
• Back pain and stiffness
• Miliary tuberculosis in which the infection spreads to the entire body through the bloodstream

Prevention of Tuberculosis (TB)

• General measures such as avoiding contact with an infected tuberculosis patient or wearing a face mask while caring or interacting with a tuberculosis case.
• Cover mouth and nose while sneezing and coughing.
• When traveling to areas where tuberculosis is prevalent, avoid crowded places.
• Good nutrition, prevention of overcrowding, adequate ventilation, and health education can be helpful to prevent the spread of tuberculosis.
• Diagnosed tuberculosis patients must complete their entire course of treatment so that they are less infectious and reduce the chances of drug-resistant tuberculosis.
• Vaccination with BCG (Bacille Calmette-Guerin) vaccine. In endemic countries like India where tuberculosis is more common, the BCG vaccine is given at birth or as early as possible before 12 months of age to protect infants and children against the more serious types of disease, such as tuberculous meningitis. ( Know more about-What is DPT Vaccine? )

We hope we were able to answer questions pertaining to Tuberculosis through this article.

You can contact a Pulmonologist for more information and treatment of Tuberculosis. 

We only aim to give you information through the article. We do not recommend medication or treatment in any way. Only a doctor can give you the best advice and correct treatment plan.