Is tuberculosis easily contagious?

Written by Wang Xiang Yu
Pulmonology
Updated on September 11, 2024
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Whether tuberculosis (TB) is easily transmitted primarily depends on the source of infection, which refers to the TB patients and the amount of Mycobacterium tuberculosis in their sputum. If TB bacilli can be detected in their sputum, and the quantity is substantial, then their infectiousness is indeed higher. However, if the TB patient has undergone treatment, or if there are only a few TB bacilli in their sputum, or none at all, then their infectiousness may not be as significant. The second factor is the mode of transmission, which mainly occurs through the respiratory tract. If TB patients can be isolated timely, or if they wear masks, and their sputum is properly managed, for example by wrapping the sputum in paper and burning it, then they are less likely to transmit the disease to others. TB generally involves susceptibility issues; even if someone has been vaccinated with BCG or the TB vaccine, they can still be reinfected. Therefore, controlling these three transmission pathways is essential to minimize the risk of contracting TB.

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Written by Wang Xiang Yu
Pulmonology
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Methods of Tuberculosis Examination

The examination methods for tuberculosis are now quite numerous, but achieving a diagnosis is still relatively difficult. The most commonly used method is still chest imaging, mainly X-rays and CT scans. Additionally, there are bacteriological examinations, such as examining sputum or other samples like pleural effusion under a microscope after staining. Culturing Mycobacterium tuberculosis, with sputum being the most commonly used sample, followed by pleural effusions and bronchoalveolar lavage fluid, is also common. A newer method is molecular biology examination, also known as Mycobacterium tuberculosis DNA nucleic acid testing. Then there is the pathological examination of tuberculosis, commonly referred to as biopsy, which involves taking a small piece of tissue from the lesion for observation. Moreover, some new immunological tests have emerged, including the traditional tuberculin skin test, still relevant today, and the gamma interferon release assays, along with traditional tests like Mycobacterium tuberculosis antibody tests. Additionally, some patients might require more invasive examinations, such as bronchoscopy, which allows direct observation of the trachea and bronchi and can be used for brush tests or biopsies at the lesion site.

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Written by Wang Xiang Yu
Pulmonology
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How to test for tuberculosis

To examine pulmonary tuberculosis, it is essential to understand that it pertains to tuberculosis changes in the lung tissue, airways, bronchi, and pleura. The pathogen causing tuberculosis is Mycobacterium tuberculosis, also known as the tubercle bacillus. There are multiple tests available for people with pulmonary tuberculosis, as the disease can vary based on location and type. Therefore, such patients generally require numerous tests. The most commonly used are imaging studies for the chest, including X-rays and CT scans. In imaging studies, most patients will show some lesions, but there are instances where tuberculosis in the airways and bronchi might not be clearly visible on CT or X-rays, necessitating more invasive tests like bronchoscopy. Additionally, bacteriological examinations, such as sputum smear and pleural fluid smear, as well as culture for Mycobacterium tuberculosis, are typically conducted for patients. Nowadays, hospitals equipped with the necessary facilities conduct molecular biological tests, namely nucleic acid testing for Mycobacterium tuberculosis DNA. Furthermore, some patients with complex conditions may require a histopathological biopsy, commonly referred to as tissue sampling, at the site of the lesion to observe under a microscope for characteristic changes indicative of tuberculosis. There are also immunological tests that assist in diagnosing tuberculosis, such as the gamma interferon release assay (commonly known as the T-SPOT), tuberculin skin test, and traditional antibody tests against Mycobacterium tuberculosis.

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Written by Yuan Lin Yan
Infectious Disease
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How long can someone with tuberculosis live?

Early detection and appropriate anti-tuberculosis treatment of tuberculosis can lead to a normal lifespan once cured. However, it is important to exercise regularly and enhance immunity, since tuberculosis may recur if the body's resistance decreases. With the increase of drug-resistant tuberculosis, treatment difficulties have intensified. If it is detected late or not treated properly and the lung damage progresses to an advanced stage, it can be life-threatening, with survival ranging from days to years. When tuberculosis involves massive hemoptysis, death can occur at any time due to suffocation or hemorrhagic shock, depending on the specific condition.

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Written by Wang Xiang Yu
Pulmonology
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Symptoms of tuberculosis

Tuberculosis of the lung presents in many forms, as there are also various types of pulmonary tuberculosis, each exhibiting different symptoms. However, the most common symptoms primarily include coughing and expectoration, which are the most typical manifestations of pulmonary tuberculosis. The cough in pulmonary tuberculosis is generally mild, either dry or producing only a small amount of phlegm. If the tuberculosis is accompanied by cavities, the amount of phlegm may be larger. If there is a bacterial infection in addition to the tuberculosis, the phlegm may become purulent. Some patients with pulmonary tuberculosis may also experience hemoptysis, which can vary in amount from light to severe. A small number of patients may suffer from chest pain and difficulty breathing. Additionally, there are systemic symptoms associated with pulmonary tuberculosis, such as fever (both low and high fever may occur), night sweats, and fatigue, among others.

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Written by Wang Xiang Yu
Pulmonology
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Local symptoms of pulmonary tuberculosis

The local symptoms of tuberculosis primarily require us to understand where tuberculosis occurs. Currently, tuberculosis in the lung tissues, trachea, bronchi, and pleura are all classified as pulmonary tuberculosis. The primary local symptoms are still respiratory symptoms, with the most common being cough and expectoration. Patients with tuberculosis generally have a slow onset, with most experiencing cough and expectoration that can persist for two weeks or more. Some patients may also exhibit symptoms like blood in the sputum or hemoptysis. Additionally, some patients may experience other symptoms; for example, those with pleural involvement might have irritative cough, chest pain, and difficulty breathing, while those with tracheobronchial involvement might exhibit a prolonged irritative cough. Some patients may also develop bronchial stenosis, which can lead to difficulty breathing.