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Tuberculosis (TB); Mycobacterium tuberculosis; Pulmonary TB; Extra pulmonary TB; TB symptoms; TB diagnosis; TB treatment; TB prevention; Latent TB infection; Active TB disease; Drug-resistant TB; TB vaccine; TB transmission; Anti-tuberculosis medications; DOTS strategy; TB public health; TB screening; TB in immunocompromised individuals; TB and HIV co-infection

Introduction

Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis. It primarily affects the lungs but can spread to other parts of the body, including the brain, kidneys, and spine [1]. Despite being preventable and treatable, TB remains a major global health concern, particularly in developing countries. The World Health Organization (WHO) identifies TB as one of the top infectious killers worldwide [2]. Tuberculosis (TB) remains one of the most pressing infectious diseases worldwide, posing a significant public health challenge, particularly in low- and middle-income countries [3]. Caused by the bacterium Mycobacterium tuberculosis, TB primarily affects the lungs (pulmonary TB) but can also impact other parts of the body such as the lymph nodes, bones, kidneys, and brain (extrapulmonary TB). Despite being a preventable and curable disease, TB continues to affect millions globally, with an estimated 10.6 million people developing TB and 1.3 million dying from it in 2022 alone, according to the World Health Organization (WHO) [4]. The spread of TB occurs through airborne transmission when individuals with active pulmonary TB cough, sneeze, or speak, releasing microscopic droplets containing the bacteria into the air [5]. People with latent TB infection harbor the bacteria in an inactive state and do not show symptoms or spread the disease, but they remain at risk of developing active TB, particularly if their immune system becomes compromised. The clinical presentation of TB can be insidious and non-specific [6]. Classic symptoms include a persistent cough, chest pain, weight loss, fatigue, fever, night sweats, and loss of appetite. However, in cases of extrapulmonary TB, symptoms can vary widely depending on the organs involved. Accurate and early diagnosis is crucial and typically involves a combination of medical history, physical examination, chest X-rays, sputum smear microscopy, culture tests, and modern molecular diagnostics such as the GeneXpert MTB/RIF assay [7].

Treatment of TB requires a long-term commitment to a multi-drug regimen, usually lasting six months or more. The standard treatment includes a combination of first-line anti-TB drugs isoniazid, rifampicin, pyrazinamide, and ethambutol. However, the emergence of drug-resistant TB (DR-TB), including multidrug-resistant TB (MDR-TB) and extensively drug-resistant TB (XDR-TB), has complicated treatment protocols and increased the need for second-line medications, which are more expensive and have greater side effects [8].

Prevention of TB involves multiple strategies, including the Bacillus Calmette-Guérin (BCG) vaccine administered in many countries at birth, improved infection control measures, active case finding, contact tracing, and treatment of latent TB infections. Public health initiatives such as the WHO’s DOTS (Directly Observed Treatment, Short-course) strategy have significantly improved TB control, particularly in resource-limited settings.

Tuberculosis

TB is caused by Mycobacterium tuberculosis (M. tuberculosis), a slow-growing bacterium. It spreads through the air when an infected person coughs, sneezes, or speaks. The bacteria become airborne and can be inhaled by others. However, not everyone exposed to the bacteria becomes sick.

The bacteria remain inactive in the body without causing symptoms. People with latent TB are not contagious but may develop active TB later.

Active TB: The bacteria multiply and cause symptoms. This form is contagious and requires immediate treatment.

Symptoms of tuberculosis

The symptoms of TB vary based on whether the infection is latent or active.

• Persistent cough lasting more than three weeks
• Coughing up blood or sputum
• Chest pain during breathing or coughing
• Unintentional weight loss
• Fatigue
• Fever and night sweats
• Loss of appetite

Symptoms of extrapulmonary TB (outside the lungs)

Swelling and pain in affected areas (e.g., spine, kidneys, or lymph nodes)

Meningitis symptoms (headache, confusion) in cases of TB affecting the brain

Joint pain if TB spreads to the bones or joints

Also known as the Mantoux test, it involves injecting a small amount of tuberculin under the skin. A raised bump indicates a positive result, but further tests are required for confirmation.

Interferon-Gamma Release Assays (IGRAs): Blood tests that measure immune response to TB bacteria. Examples include QuantiFERON-TB Gold and T-SPOT.TB.

Chest X-ray or CT scan: These imaging tests help detect lung abnormalities caused by TB.

Sputum Tests: Sputum samples are tested using smear microscopy, culture tests, or nucleic acid amplification tests (NAAT) to detect TB bacteria.

Treatment of tuberculosis

TB is treatable with a combination of antibiotics. Treatment duration typically lasts six months, but it may vary based on the type and severity of the infection.

First-line TB Drugs:

• Isoniazid (INH)
• Rifampin (RIF)
• Ethambutol (EMB)
• Pyrazinamide (PZA)

For drug-resistant TB, second-line medications such as fluoroquinolones and injectable agents like amikacin or capreomycin are used.

Directly Observed Therapy (DOT) is recommended to ensure patients complete their treatment regimen, preventing drug resistance and relapse.

Multidrug-Resistant TB (MDR-TB) and Extensively Drug-Resistant TB (XDR-TB)

MDR-TB occurs when the TB bacteria become resistant to isoniazid and rifampin, the two most powerful TB drugs. XDR-TB is a more severe form, resistant to first-line and second-line antibiotics. Treating MDR-TB and XDR-TB is more complex and requires longer, more toxic and expensive regimens.

Preventing TB involves both medical interventions and public health measures:

Vaccination — the Bacillus Calmette-Guérin (BCG) vaccine is used in countries with a high prevalence of TB. It provides partial protection against TB, especially in children.

Infection control — in healthcare settings, TB precautions include wearing masks, proper ventilation, and isolating infectious patients.

Preventive Therapy — people with latent TB, especially those with weakened immune systems, are treated with isoniazid or a combination of isoniazid and rifapentine to prevent progression to active TB.

Public Awareness and Screening — regular screening and education in high-risk communities help prevent the spread of TB.

Conclusion

Tuberculosis remains a major public health threat, despite being preventable and treatable. Early diagnosis, effective treatment, and preventive measures are critical in reducing the disease burden. Global cooperation, public awareness, and investment in healthcare infrastructure are essential to achieving the goal of TB elimination. Understanding TB in its entirety — from its causes and symptoms to diagnostic tools, treatment approaches, and preventive strategies — is vital not only for healthcare professionals but also for the general public. Raising awareness and reinforcing efforts at local, national, and global levels is essential to achieving the WHO's goal of ending the TB epidemic by 2030. This article delves into the causes, symptoms, diagnosis, treatment, and prevention of TB, offering a comprehensive overview of this enduring global health threat.

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