Tuberculosis is transmitted through the air.

Written by Wang Xiang Yu
Pulmonology
Updated on April 20, 2025
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The transmission of tuberculosis primarily depends on understanding its causative agent, which is the tubercle bacillus, also known simply as the tuberculosis bacillus. The main source of infection in tuberculosis is from patients who test positive for tuberculosis bacillus in their sputum. The respiratory tract is the principal route of transmission for tuberculosis patients. When patients who test positive for bacillus in their sputum cough, expel sputum, sneeze, or even speak loudly, they generate a large amount of droplets containing the tuberculosis bacillus. These bacteria can remain suspended in the air for a relatively long time. In poorly ventilated indoor environments, they may stay airborne for up to five hours. Healthy individuals can contract respiratory infections upon inhaling these bacteria. Furthermore, a very small portion of patients are infected through consuming milk or other dairy products from cows with tuberculosis.

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Written by Wang Xiang Yu
Pulmonology
57sec home-news-image

Can you get tuberculosis on your own?

This question can be interpreted in two ways. First, whether every individual could potentially contract tuberculosis (TB) – to that, the answer is yes. Tuberculosis is a contagious disease, and we are all susceptible to the TB bacterium. Therefore, there is a chance, in our lifetimes, to be infected by the TB bacterium and consequently develop TB. The second interpretation revolves around whether a person could suddenly develop TB without specific reasons. Generally, this does not happen. In other words, a typical person would not contract TB unless they have been exposed to the TB bacterium. This means one does not contract TB arbitrarily; it occurs only after coming into contact with TB patients or the TB bacterium, leading to an infection in the lungs and resulting in TB.

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Written by Li Jiao Yan
Neonatology
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Does the BCG vaccine prevent tuberculosis?

The BCG vaccine primarily prevents infection by the tuberculosis bacillus, so it can prevent pulmonary tuberculosis. The protective effect of the BCG vaccine is mainly achieved through inducing a cell-mediated immune response. After vaccination, a primary infection is formed, which is processed by macrophages that transmit the antigen information to immune-active cells, leading to the differentiation and proliferation of T cells and the formation of sensitized lymphocytes. When the body is re-infected with the tuberculosis bacillus, the macrophages and sensitized lymphocytes are activated, causing a specific immune response in the body, thereby resisting the infection by the tuberculosis bacillus. Therefore, the BCG vaccine mainly prevents pulmonary tuberculosis.

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Written by Xiong Hong Hai
Infectious Disease
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How is tuberculosis diagnosed?

The diagnosis of tuberculosis primarily involves combining relevant clinical symptoms, such as whether there is cough, expectoration, low fever, night sweats, and blood in phlegm. It also requires considering the patient's chest imaging features, whether there is obvious infection, fresh exudation, cavities, as well as sputum tests. For example, if the sputum stain for acid-fast bacilli is positive, and the sputum culture is positive, using these comprehensive diagnostic methods, tuberculosis can be diagnosed, after which anti-tuberculosis treatment should be initiated.

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Written by Wang Xiang Yu
Pulmonology
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Can tuberculosis be fatal?

Can tuberculosis be fatal? Of course, the answer is yes. Many diseases can lead to death, even a common cold can potentially result in death, let alone tuberculosis, which is an extraordinary illness. Currently, the mortality rate for tuberculosis patients is relatively low because the treatment for tuberculosis has improved significantly compared to the past. However, there are still a small number of patients who, due to untimely treatment of tuberculosis, discontinuation of medications on their own accord or non-compliance with medical advice, or who have other serious underlying diseases, may not tolerate the tuberculosis treatment. As a result, they could potentially die from adverse reactions to the tuberculosis medications.

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Written by Wang Chun Mei
Pulmonology
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Does tuberculosis cause fever in its initial stage?

Tuberculosis is caused by an infection of the lungs by the bacterium Mycobacterium tuberculosis, and it is a very common infectious respiratory disease clinically. Typically, the early stage of tuberculosis is accompanied by mild fever to varying degrees, usually occurring in the afternoon, along with coughing, expectoration of blood, chest tightness, shortness of breath, and even chest pain, weight loss, fatigue, and night sweats as accompanying clinical symptoms. In the early stages, the diagnosis of tuberculosis in patients is generally made through these specific clinical symptoms, along with some sputum culture and chest X-ray examinations. Usually, most patients with early-stage tuberculosis will experience symptoms of low-grade fever, but these patients have a characteristic of fever that occurs in the afternoon and does not require antipyretics as it can return to normal by itself in the evening.