Tuberculosis

UPDATED ON: 22 Feb 2024, 16:16 PM

Medically Reviewed by

Dr Manav Manchanda

What is Tuberculosis?

Causes of Tuberculosis

Here are 5 causes that contribute to its prevalence and transmission:

1. Bacterial transmission: TB spreads through the air when an infected person coughs, sneezes, or talks, releasing tiny infectious droplets containing the bacteria. Close and prolonged contact with an infected individual increases the risk of transmission.

2. Weak immune system: People with compromised immune systems, such as those living with HIV/AIDS, malnutrition, or certain chronic diseases like diabetes, are more susceptible to TB infection due to their inability to fight against the bacteria.

3. Overcrowded and poorly ventilated settings: TB thrives in overcrowded and poorly ventilated environments, such as prisons, refugee camps, and homeless shelters. In these settings, close contact among individuals facilitates the spread of the bacteria.

4. Lack of access to healthcare: Limited access to healthcare services, including diagnostic tools and treatment, contributes to TB prevalence.

5. Drug resistance: Misuse or incomplete courses of antibiotics can lead to the development of drug-resistant strains of TB.

Risk factors of tuberculosis

While TB is caused by exposure to Mycobacterium bacteria, some risk factors increase your chances of developing this disease:

• Having a weakened immune system significantly increases susceptibility to TB. This includes conditions like HIV/AIDS, malnutrition, and certain medications (e.g., corticosteroids or chemotherapy) that suppress the immune response.
• Individuals aged 65 and older, as well as young children, face heightened susceptibility due to developing or weakened immune systems, respectively.
  Poverty, overcrowded living conditions, and a lack of access to healthcare amplify TB risk.
• Substance abuse, particularly alcohol and tobacco, can compromise immune function and increase vulnerability.
• Undernourished people are also at higher risk of TB as compared to healthy people.
• People who are suffering from diabetes and are on medicines such as steroids also exacerbate the risk of TB infection and progression to active disease.

Key Facts About Tuberculosis

Major Symptoms	Persistent cough lasting more than three weeks Coughing up blood or sputum Chest pain Chronic fatigue Fever Night sweats Unintentional weight loss Loss of appetite
Necessary Health Tests	Medical history Tuberculin skin test (TST) Blood test Sputum analysis Imaging studies
Treatment	Antibiotics (for 6–9 months of course) Other medications such as isoniazid, rifampin, ethambutol, and pyrazinamide Healthy diet Lifestyle modifications

Symptoms of Tuberculosis

Tuberculosis presents a variety of symptoms that can vary depending on the stage of infection and the type of TB such as brain, kidneys, bones, intestine, and genitals. But TB of the lungs is the most common type of it. Here are common symptoms of TB:

• Persistent cough lasting more than three weeks
• Coughing up blood or sputum
• Chest pain
• Chronic fatigue
• Fever
• Night sweats
• Unintentional weight loss
• Loss of appetite

In some cases, TB can affect other parts of the body, leading to symptoms such as swollen lymph nodes, joint pain, abdominal pain, and a general feeling of illness. However, not everyone infected with TB bacteria develops symptoms, especially in the latent stage when the immune system keeps the bacteria under control.

Types of Tuberculosis

Tuberculosis is a contagious bacterial infection caused by Mycobacterium tuberculosis. It primarily affects the lungs but can also affect other body parts, each with distinct characteristics, treatment, and management. Here are the most common types of TB:

1. Pulmonary TB

Pulmonary TB is the most common form of the disease, affecting the lungs. It typically presents with symptoms such as persistent coughing, chest pain, coughing up blood, fatigue, weight loss, and fever. Pulmonary TB can be further classified into:

• Drug-susceptible TB: This refers to TB strains that are susceptible to standard antibiotics like isoniazid and rifampicin.
• Drug-resistant TB: This form of TB occurs when the bacteria develop resistance to one or more of the first-line drugs used to treat the infection. Drug-resistant TB can be further categorised as multi-drug-resistant TB (MDR-TB) or extensively drug-resistant TB (XDR-TB), depending on the extent of resistance.

2. Active TB

Active TB refers to when the infection spreads beyond the lungs to other parts of the body. Common sites of extra-pulmonary TB include the lymph nodes, bones, joints, meninges, abdomen, and genitourinary tract. Symptoms vary depending on the affected area and may include swelling, pain, neurological symptoms, or abdominal discomfort.

3. Latent TB infection (LTBI)

Latent TB infection occurs when a person has been infected with the TB bacteria but does not have the disease. Individuals with LTBI do not experience symptoms and are not contagious. However, they are at risk of developing active TB if the bacteria become active due to factors such as a weakened immune system caused by diseases such as HIV.

4. Miliary TB

Miliary TB is a rare and severe form of the disease where the bacteria spread through the bloodstream to various organs, leading to millet seed-sized tiny lesions. This can result in widespread symptoms and organ dysfunction.

Diagnosis of Tuberculosis

Tuberculosis (TB) diagnosis involves a multifaceted approach to confirm the presence of the disease accurately.

1. Medical history: The process typically begins with a thorough medical history review and physical examination. Symptoms such as persistent coughs, weight loss, night sweats, and fatigue often indicate TB. However, these symptoms can overlap with other conditions, which makes it essential to do some tests.

2. Tuberculin skin test (TST): One primary method for TB diagnosis is the tuberculin skin test (TST), also known as the Mantoux test. A small amount of tuberculin is injected into the skin, usually on the forearm. After 48 to 72 hours, if there is swelling, and the skin is hard, it is considered a positive result. It indicates exposure to the TB bacteria but does not necessarily confirm active disease.

3. Blood test: Another crucial diagnostic tool is the interferon-gamma release assay (IGRA), which measures the immune response to TB bacteria.

4. Sputum analysis: Analysis of sputum involves utilising tests such as AFB stain (ZN Stain), sputum culture, and Mycobacterium tuberculosis DNA PCR – Qualitative – Sputum. These diagnostic procedures aim to detect the presence of tuberculosis bacteria within the sputum samples. A positive result confirms the diagnosis of tuberculosis.

5. Imaging studies: Imaging studies, such as chest X-rays or computed tomography (CT) scans, play a vital role in TB diagnosis by revealing abnormalities in the lungs or other affected organs. These images help assess the extent of the disease and monitor the treatment response.

Treatment of Tuberculosis

The treatment of tuberculosis (TB) typically involves a combination of antibiotics over an extended period, usually ranging from six to nine months. This approach is crucial due to the bacteria’s ability to develop resistance to single drugs. Treatment regimens may vary based on factors such as the type of TB (drug-sensitive or drug-resistant), the patient’s overall health, and the presence of any underlying conditions.

The primary medications used in TB treatment include isoniazid, rifampin, ethambutol, and pyrazinamide. The first phase of treatment, known as the intensive phase, typically lasts for two months and involves a combination of several drugs to quickly eliminate active bacteria. This phase aims to reduce the bacterial load in the body and prevent the development of drug resistance.

The second phase, known as the continuation phase, follows the intensive phase and involves a reduced number of medications taken over a longer period to completely eradicate any remaining bacteria.

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