How does the human body become infected with tuberculosis? Do you need to be treated immediately after infection?

Author: Li Liang, Chief Physician, Beijing Chest Hospital, Capital Medical University

Former Chairman of the Tuberculosis Branch of the Chinese Medical Association

Reviewer: Mi Yuhong, Chief Physician, Beijing Anzhen Hospital, Capital Medical University

On March 24, 1882, the famous German scientist Robert Koch announced his discovery of the tuberculosis bacillus.

Mycobacterium tuberculosis is a very small bacterium. Some people may ask, how small is it? If 60 Mycobacterium tuberculosis are lined up together, it is roughly equivalent to the diameter of a hair.

Although tuberculosis bacteria are small, they are very harmful. Around the world, about 10 million people suffer from tuberculosis every year due to infection with tuberculosis bacteria. This is a very large population.

1. How does the human body become infected with Mycobacterium tuberculosis?

The main way that Mycobacterium tuberculosis infects the human body is through the respiratory tract.

Figure 1 Original copyright image, no permission to reprint

Mycobacterium tuberculosis has no legs and cannot move and spread on its own. If it wants to get out of the human body, it must use a "vehicle", that is, droplet nuclei.

When people cough, sneeze, talk, or sing, they produce a lot of droplet nuclei. Mycobacterium tuberculosis can spread into the air with the droplet nuclei. If someone happens to pass by nearby, the droplet nuclei floating in the air may enter the person's body and cause infection.

Of course, infection and disease are two different concepts. Studies have found that after tuberculosis bacteria enter the human body, only 5%-10% of people will develop tuberculosis, so there is no need to worry too much.

2. Under what circumstances does treatment require after being infected with Mycobacterium tuberculosis?

After a person is infected with tuberculosis bacteria, three situations may occur:

First, the virulence of the infected tuberculosis bacilli is very weak, while the human body has a strong resistance, so the human body can eliminate the tuberculosis bacilli by itself, so there will be no disease and no symptoms. In this case, no treatment is needed.

Second, if the body's resistance is relatively weak, such as those who have recently undergone major surgery or have underlying diseases, the virulence of tuberculosis bacteria is very strong, and it will multiply in large numbers in the human body, causing illness and various tuberculosis symptoms. In this case, active treatment is definitely needed.

Third, the body's resistance and the toxicity of tuberculosis bacteria are temporarily in a state of balance. In the future, if the body's resistance decreases, tuberculosis bacteria will take the opportunity to multiply rapidly, leading to illness, and active treatment should also be given.

Studies have found that tuberculosis can remain dormant in the human body for months, years, or even decades. Many elderly people get tuberculosis because they were infected with tuberculosis when they were young. As they get older, their body's resistance decreases and they eventually get sick.

Therefore, in order to avoid future illness, active treatment under the guidance of a professional doctor is required after discovering this situation.

3. How often should you go to the hospital for a checkup during tuberculosis treatment?

The treatment of tuberculosis is a relatively long process, and some adverse reactions may occur during the treatment. Therefore, follow-up is very important to ensure that tuberculosis patients can complete treatment safely and effectively.

If the follow-up interval is too long, it may affect the detection of adverse reactions, but if it is too short, it will cause great inconvenience to the patient's daily life, and the impact of tuberculosis patients on the people around them will still exist.

Therefore, it is generally believed that it is very important to conduct a follow-up visit about once a month to assess the patient's current condition by doing some necessary tests, such as liver function and kidney function tests, as well as some imaging tests and some bacteriological tests.

Figure 2 Original copyright image, no permission to reprint

Follow-up once a month or so is now a generally accepted frequency, but with the development of Internet hospitals or remote consultations, it may be possible in the future that patients will not need to come to the hospital for follow-up, but can complete the follow-up at home through electronic communication equipment.

4. How long does it take to treat tuberculosis before it becomes non-contagious?

Tuberculosis is an infectious disease. With regular treatment, the infectiousness of tuberculosis will decrease significantly or disappear in about one and a half months. Therefore, it is not the case that tuberculosis patients are always infectious during treatment.

Of course, not being contagious does not mean that you are cured.

Tuberculosis is considered cured only when a tuberculosis patient follows the doctor's advice, takes the medicine according to the course of treatment, and no tuberculosis bacteria are found in two consecutive sputum tests.

If you stop taking the medicine at will before you are cured, it may easily induce drug resistance and increase the possibility of relapse. Once the disease relapses, it will become contagious again. Therefore, it is very important to take the medicine as prescribed by the doctor during treatment.