Tuberculosis, often abbreviated as TB, is a highly infectious disease caused by the bacterium Mycobacterium tuberculosis, primarily affecting the lungs but capable of impacting other body parts. It ranks as one of the top infectious disease killers globally, with a significant incidence in developing countries due to factors like inadequate healthcare and living conditions. Prevention and control strategies, including vaccination with the BCG vaccine and prompt treatment with antibiotics, are crucial in combating the spread of TB.

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Table of contents

    What Is Tuberculosis?

    Tuberculosis (TB) is a highly infectious disease that primarily affects the lungs but can also affect other parts of the body. It's caused by the bacterium Mycobacterium tuberculosis. Despite being a preventable and curable disease, TB remains a significant public health issue in many parts of the world.

    Understanding Tuberculosis: A General Overview

    Tuberculosis is a global health concern, with millions of new cases reported annually. The disease spreads through the air when a person with active TB in their lungs coughs, sneezes, or even speaks, releasing microscopic droplets that contain the bacteria. Not everyone infected with TB bacteria becomes sick, leading to the distinction between latent TB infection (LTBI) and active TB disease. People with LTBI do not show symptoms, are not contagious, and can possibly never develop TB disease. However, they may progress to active TB, particularly if their immune system weakens.In understanding TB, it's critical to grasp the significance of its symptoms. Active pulmonary TB symptoms include a persistent cough that lasts three weeks or longer, chest pain, coughing up blood, fatigue, weight loss, fever, and night sweats. If TB affects other parts of the body, the symptoms differ depending on the affected area.

    Did You Know? The BCG vaccine, primarily used in high TB incidence countries, offers protection against the most severe forms of TB in children, such as TB meningitis and miliary TB. However, its effectiveness in preventing pulmonary TB in adults is variable and widely debated. The vaccine's role in global TB control strategies, especially in countries with low TB incidence, emphasizes the complexities of TB prevention and highlights the need for new, more effective vaccines.

    Causes of Tuberculosis: How It Starts

    The primary cause of tuberculosis is the bacterium Mycobacterium tuberculosis. This bacterium is remarkable for its ability to survive in an inactive state within the body for years, sometimes never causing any symptoms. However, about 5-10% of individuals with latent TB infection will develop active TB disease at some point in their lives. The likelihood increases in certain circumstances, such as when a person's immune system is weakened by other health conditions, malnutrition, aging, or specific treatments like chemotherapy.Factors contributing to TB transmission include:

    • Close contact with someone who has active TB, especially in crowded or enclosed spaces.
    • HIV infection, which significantly weakens the immune system.
    • Substance use, including tobacco and alcohol, which can lower immune system efficiency.
    • Living or traveling to areas with high TB prevalence.
    Understanding these factors is vital for prevention and control measures to be effective. Each highlights the importance of public health strategies, such as early detection, treatment of active TB cases, and targeted testing and treatment of latent TB infection, especially among high-risk populations.

    Latent TB infection can lie dormant for years without causing symptoms. A healthy immune system can often prevent the progression to active TB disease.

    Tuberculosis Symptoms and Detection

    Identifying and diagnosing Tuberculosis (TB) early plays a crucial role in controlling the spread of this infectious disease. Understanding the symptoms and the testing methods available is key to combating TB effectively. This section sheds light on how to recognise TB symptoms and the various tests used for its diagnosis.

    Recognising Tuberculosis Symptoms

    Recognising the symptoms of TB early can significantly increase the chances of successful treatment and reduce the risk of spread. Pulmonary TB, which affects the lungs, presents the most common symptoms including:

    • Persistent cough lasting more than three weeks, often with sputum
    • Chest pain
    • Coughing up blood
    • Fatigue
    • Weight loss
    • Night sweats
    • Fever
    However, TB can also affect other parts of the body, leading to a wide range of symptoms depending on the organs involved. It's crucial to seek medical advice if you or someone you know exhibits these symptoms, especially if there is known exposure to TB.

    Example: A person with TB affecting the lymph nodes might notice swollen glands, whereas someone with TB of the spine could experience back pain and stiffness. These examples highlight the variety in TB symptoms, underscoring the need for awareness and prompt investigation.

    Tuberculosis Test: How Is It Diagnosed?

    Diagnosing TB involves a combination of medical history, physical examination, and specific tests. The most common tests for detecting TB are:

    • Tuberculin Skin Test (TST): Also known as the Mantoux test, it involves injecting a small amount of fluid called tuberculin into the skin of the lower arm. A healthcare professional checks the injection site 48 to 72 hours later for a reaction.
    • Interferon-Gamma Release Assays (IGRAs): These blood tests measure the immune system's response to TB bacteria. Examples include the QuantiFERON®-TB Gold Plus (QFT-Plus) test and the T-SPOT®.TB test.
    • Chest X-ray: A chest x-ray can show the extent of damage to the lungs and is usually done if a TST or IGRA is positive.
    • Sputum tests: These are used to confirm TB bacteria's presence in people with symptoms of pulmonary TB. It involves examining the sputum (phlegm) under a microscope or culturing it to grow the bacteria.
    In some cases, additional tests such as a CT scan or biopsy might be necessary to diagnose TB in organs other than the lungs. Early detection and treatment are essential to controlling the spread of TB and reducing the risk of complications.

    Technological Advances: Recent years have seen significant advancements in TB diagnostics, including the development of rapid molecular tests, such as the GeneXpert MTB/RIF assay. This test detects both TB bacteria and resistance to rifampicin, one of the key TB drugs, in less than two hours, significantly speeding up the diagnosis and treatment initiation process.Moreover, ongoing research into novel biomarkers and improved tests holds the promise of making TB diagnosis even more efficient and accessible, especially in high-burden countries. These advancements are critical in the global fight against TB, aiming to achieve the targets set by the End TB Strategy by the World Health Organization.

    A positive TB skin test or blood test alone does not confirm active TB disease. These tests indicate that the person has been infected with TB bacteria, but additional tests are necessary to determine if the infection is latent or active.

    Is Tuberculosis Contagious?

    Many might wonder about the contagious nature of Tuberculosis (TB). The short answer is yes, TB is indeed contagious, but it primarily spreads under specific conditions. Understanding how TB is transmitted and the steps you can take to protect yourself and others is key to preventing its spread.

    Tuberculosis Transmission: How It Spreads

    The transmission of TB is a process that might sound alarming, but with appropriate knowledge, the risk can be effectively managed. TB spreads through the air; when a person with active pulmonary TB coughs, sneezes, speaks, or sings, they release tiny droplets containing the Mycobacterium tuberculosis bacterium into the air. If another person inhales these droplets, they can become infected. However, TB is not as easily spread as the common cold or flu. It generally requires prolonged, close contact with someone who has the active disease. For instance, living or working with someone with active TB increases the risk of getting infected.

    Example: Imagine being in a poorly ventilated room for several hours with someone who has active TB; the chances of inhaling enough bacteria to become infected are higher than in well-ventilated or outdoor spaces.

    Protecting Yourself and Others

    Protecting against tuberculosis involves a multifaceted approach. If you're at high risk of being exposed to TB, or if you've been exposed, it's important to be proactive in taking precautionary measures. Here are some steps to consider:

    • Avoid close contact or prolonged time with known TB patients in enclosed spaces.
    • Ensure good ventilation in living and working environments to reduce the concentration of airborne bacteria.
    • Use protective masks if you're a healthcare worker or if you're taking care of a person with active TB.
    • Get tested regularly if you belong to a high-risk group or have been exposed to TB.
    • Consider vaccination with the BCG vaccine if recommended and appropriate for your situation.

    While the BCG vaccine can offer protection against TB, its efficacy can vary based on geographic location and the individual. Also, the vaccine is more effective in preventing severe forms of TB in children than in adults. Hence, relying solely on vaccination is not a foolproof protection strategy, especially in high prevalence areas or for those at increased risk.

    TB transmission is more likely to occur from someone with active TB. People with latent TB infection (LTBI) do not spread the disease.

    Treating Tuberculosis

    When it comes to treating Tuberculosis (TB), there are several effective options available that have been proven to cure patients and help control the spread of the disease. The treatment journey for someone diagnosed with TB can vary depending on the nature and severity of the infection, as well as whether the TB strain is drug-resistant.

    Tuberculosis Treatment: What Are Your Options?

    The mainstay of TB treatment is a course of antibiotics. Since TB is caused by a bacterium, antibiotics are effective in killing the bacteria in most cases. However, because TB bacteria grow slowly and can survive in a dormant state within the body, the treatment course is longer than that for most bacterial infections, typically lasting for at least six months. The most common treatment regimen for new cases of active, drug-sensitive TB is a combination of four antibiotics:

    • Isoniazid
    • Rifampicin
    • Pyrazinamide
    • Ethambutol
    Adhering strictly to the prescribed treatment plan is critical to prevent the development of drug-resistant TB. In cases where the TB strain is resistant to the standard antibiotics, a more complex and longer treatment with second-line antibiotics is required.

    The challenge of Multi-Drug Resistant TB (MDR-TB) and Extensively Drug-Resistant TB (XDR-TB) has necessitated the use of more powerful and, unfortunately, often more toxic drugs, which can have significant side effects. These treatments can last up to two years and may involve injectable medications, making adherence even more challenging for patients.

    Example: A patient diagnosed with drug-resistant TB might be prescribed a regimen including newer drugs like bedaquiline or linezolid as part of a longer treatment course tailored to the specific resistance pattern of the TB bacteria infecting them.

    Tuberculosis Vaccine: Preventing the Disease

    BCG vaccine: The Bacille Calmette-Guérin (BCG) vaccine is the only vaccine currently available for Tuberculosis (TB) and has been in use since 1921. It is primarily used to protect infants and young children against the most severe forms of TB, such as TB meningitis and miliary TB, in countries where TB is common.

    The efficacy of the BCG vaccine in preventing pulmonary TB in adults is variable and appears to diminish over time. As a result, the vaccine is not typically used for TB control in adults, especially in countries with a low incidence of TB. Research into more effective vaccines, both to prevent TB and to protect against all forms of the disease, including in adults, is ongoing.

    The BCG vaccine is more effective in preventing severe TB in children than in adults. It does not provide lifelong immunity against TB.

    Recent advancements in TB vaccine research include innovative approaches like mRNA vaccines, which have been propelled into the spotlight by their use in COVID-19 vaccines. These novel technologies offer hope for more effective TB vaccines in the future, potentially transforming TB prevention and control efforts worldwide.

    Tuberculosis - Key takeaways

    • What is Tuberculosis: Tuberculosis (TB) is an infectious disease primarily affecting the lungs, caused by Mycobacterium tuberculosis.
    • Tuberculosis Symptoms: Persistent cough, chest pain, coughing up blood, fatigue, weight loss, fever, and night sweats for pulmonary TB; varied symptoms for other body parts.
    • Tuberculosis Test: Includes the Tuberculin Skin Test (TST), Interferon-Gamma Release Assays (IGRAs), chest X-rays, and sputum tests.
    • Tuberculosis Vaccine: The BCG vaccine is used primarily in children to protect against severe forms of TB, with variable effectiveness in adults.
    • Tuberculosis Treatment: Involves a combination of antibiotics like Isoniazid, Rifampicin, Pyrazinamide, and Ethambutol for at least six months.
    Frequently Asked Questions about Tuberculosis
    What are the primary symptoms of tuberculosis?
    The primary symptoms of tuberculosis include a persistent cough that lasts more than three weeks, often with phlegm and sometimes blood, chest pain, weight loss, fever, night sweats, and tiredness.
    Is there a vaccine available for tuberculosis?
    Yes, there is a vaccine available for tuberculosis called the Bacillus Calmette-Guérin (BCG) vaccine. It is most commonly given to children in countries where TB is prevalent.
    How is tuberculosis transmitted?
    Tuberculosis (TB) is transmitted from person to person through airborne particles when someone with active TB disease in their lungs coughs, sneezes, speaks, or sings, releasing bacilli into the air. When another person inhales these particles, they can become infected.
    What are the treatment options for tuberculosis?
    Treatment options for tuberculosis include a combination of antibiotics, such as isoniazid, rifampicin, pyrazinamide, and ethambutol, taken over a minimum of 6 months. In cases of drug-resistant TB, longer courses with different, more potent medications may be required. Treatment adherence is crucial to success.
    Can tuberculosis be cured completely?
    Yes, tuberculosis (TB) can usually be cured completely with a course of antibiotics that lasts for at least six months, following the treatment regimen precisely as prescribed by a healthcare professional.

    Test your knowledge with multiple choice flashcards

    Which of the following strategies should not be used to tackle TB outbreaks?

    What is Tuberculosis?

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