Tuberculosis science: Why do you need to take a chest X-ray after coughing for two weeks?

1. What is tuberculosis?

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis, which is mainly transmitted through droplets. When a patient coughs, sneezes or speaks loudly, droplets containing tuberculosis bacteria can be inhaled by others, causing infection. Tuberculosis bacteria most often invade the lungs (accounting for more than 80%), which is called pulmonary tuberculosis; it can also invade other organs such as lymph nodes, bones, and kidneys, which is called extrapulmonary tuberculosis.

2. Why should you be alert to tuberculosis after coughing for two weeks?

A cough caused by a common cold or bronchitis usually goes away within 1-2 weeks, but a cough caused by tuberculosis has different characteristics:

Long duration: Tuberculosis cough usually lasts more than 2 weeks and is not effectively treated with common cough suppressants and antibiotics.

Associated symptoms: low fever (mainly in the afternoon), night sweats, fatigue, weight loss, blood in sputum, etc.

Latent: Early symptoms are mild and easily mistaken for a "cold", but the condition will gradually worsen and may even cause lung cavitation or spread.

Note: Not all long-term coughs are tuberculosis, but tuberculosis is a "high-risk disease" that must be ruled out first - because it is contagious and delayed treatment may lead to serious consequences.

3. Why do we need to take a chest X-ray? ——Four core reasons

Tuberculosis's "invisibility": atypical symptoms

After tuberculosis infects the lungs, the initial symptoms may be only a mild cough, and the patient may not even feel any obvious discomfort. However, at this time, infiltrative lesions (inflammation), nodules, or calcifications may have already appeared in the lungs.

The role of chest X-ray: directly observe whether there are abnormal shadows in the lungs, such as: infiltration shadows in the upper lung field (a common site for pulmonary tuberculosis). Cavity formation (a typical manifestation in the late stage, with a large number of tuberculosis bacteria in the cavity, which is highly contagious). Miliary nodules (hematogenous disseminated tuberculosis).

A key tool for identifying other diseases

The causes of long-term cough are complex and may include pneumonia, bronchitis, asthma, lung cancer, etc. A chest X-ray can help doctors quickly distinguish:

- Pneumonia: patchy, blurred shadows, often confined to a certain lobe of the lung.

- Lung cancer: a mass or lobulated nodule, possibly with lymphadenopathy.

- Pulmonary tuberculosis: multiple lesions, usually in the apex or upper lung fields, which may be accompanied by calcifications or cavitations.

3. Public health prevention and control: early detection and early isolation

Tuberculosis is a statutory Class B infectious disease. Once cases occur in collective units such as schools and dormitories, it is very likely to cause an outbreak of an epidemic.

Chest X-ray screening: quickly identify suspected patients, isolate and treat them in a timely manner, and cut off the transmission chain.

Case: A student had a cough for two weeks without paying attention. A chest X-ray revealed cavitary tuberculosis, which led to the infection of three other people in the same dormitory.

4. Guide follow-up examination and treatment

A chest X-ray is the "first step" in diagnosing tuberculosis:

If the chest X-ray is abnormal, further testing is required including sputum smear (to look for tuberculosis bacteria), sputum culture (gold standard for diagnosis), and molecular testing (such as Xpert MTB/RIF, to detect drug resistance).

If the chest x-ray is normal but symptoms are suspicious, chest CT (which has higher resolution and can detect subtle changes) may be necessary.

4. Is it safe to take a chest X-ray? Will the radiation harm the body?

The radiation dose is extremely small: the radiation dose of a chest X-ray is about 0.1mSv, which is equivalent to 10 days of background radiation in the natural environment and has almost no effect on the human body.

The benefits far outweigh the risks: the radiation from chest X-rays is negligible compared to the disease spread and health damage caused by missed TB diagnosis.

5. If tuberculosis is suspected, what other tests need to be done?

Sputum test: Collect sputum in the early morning for 3 consecutive days to check for acid-fast bacilli (tuberculosis bacteria).

PPD or IGRA: to determine whether the patient has been infected with tuberculosis.

Chest CT: It can show tiny lesions more clearly, especially for patients with normal chest X-ray but persistent symptoms.

6. How to prevent tuberculosis?

Bacillus Calmette-Guérin (BCG) vaccination: mainly used to prevent severe tuberculosis in children, but it cannot completely prevent infection.

Maintain ventilation: Open windows in classrooms and dormitories frequently to reduce the accumulation of droplets.

Enhance immunity: Eat a balanced diet and maintain a regular schedule. Tuberculosis bacteria often cause disease when the immune system is low.

Early diagnosis and early treatment: If you have a cough for more than 2 weeks accompanied by low fever and night sweats, seek medical attention immediately!

Summarize

Taking a chest X-ray after coughing for two weeks is not an exaggeration by the doctor, but because:

- Tuberculosis has hidden symptoms, but is highly contagious and harmful;

- Chest X-ray is a "scout" for rapid screening of lung lesions;

- Early detection can protect both yourself and others’ health.

Remember: If you have a persistent cough, don’t just bear it! A chest X-ray can give you peace of mind.