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How is tuberculosis transmitted?

Dec 01, 2025 Source: Cainiu Health
Dr. Ren Yi
Introduction
Tuberculosis can be transmitted through droplets, aerosols, close contact, the digestive tract, and from mother to child. Droplet transmission is the primary mode of tuberculosis spread. When individuals with active pulmonary tuberculosis cough, sneeze, speak, or sing, they release droplets containing Mycobacterium tuberculosis. Healthy individuals who inhale these droplets may become infected.

Generally, tuberculosis can be transmitted through droplet transmission, aerosol transmission, close contact transmission, gastrointestinal transmission, and mother-to-child transmission. The details are as follows:

1. Droplet transmission: This is the primary mode of tuberculosis transmission. When patients with active pulmonary tuberculosis cough, sneeze, speak, or sing, they release droplets containing Mycobacterium tuberculosis. Healthy individuals who inhale these droplets may become infected, especially in enclosed spaces where the risk is higher.

2. Aerosol transmission: Droplets expelled by patients gradually dry in the air, forming tiny droplet nuclei (aerosols) that can remain suspended for extended periods. Healthy individuals may inhale air containing these aerosols and become infected even at a distance from the patient.

3. Close contact transmission: Living, working, or studying closely with a person who has active pulmonary tuberculosis increases the risk of infection due to frequent exposure to the patient’s secretions such as saliva and sputum. For example, among family members or coworkers, inadequate protective measures can easily lead to disease spread.

4. Gastrointestinal transmission: Although less common, this route is still possible. If healthy individuals consume food contaminated with Mycobacterium tuberculosis or drink unpasteurized milk from infected sources, the bacteria may enter the body through the digestive tract and cause intestinal tuberculosis.

5. Mother-to-child transmission: If a pregnant woman has active tuberculosis, Mycobacterium tuberculosis may pass through the placental circulation to the fetus, or the newborn may become infected during delivery by coming into contact with the mother's secretions. However, with proper medical intervention, the risk of mother-to-child transmission can be significantly reduced.

In daily life, it is important to maintain indoor ventilation and avoid crowded, enclosed environments. When in contact with tuberculosis patients, wearing masks and taking protective measures is essential. Regular health check-ups are recommended, and individuals experiencing symptoms such as persistent cough, low-grade fever, or night sweats should seek prompt medical evaluation.

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