When is tuberculosis contagious


Information for relatives

If a patient is suspected of having tuberculosis or has already been diagnosed with infectious tuberculosis requiring treatment, it is important to protect those close to them from infection. To find out which precautionary measures to take and what to consider with regard to a transmission that may have already occurred, please contact your pulmonologist directly.

Particular risk of infection

Tuberculosis is typically caused by tiny droplet nuclei (aerosols, aerosols
Aerosols are mixtures of solid or liquid particles in a gas mixture such as air. The tiny particles can float in it for a long time. ) which contain tuberculosis bacteria. In the event of contact with infectious tubercular patients, the patient and the contact person should therefore wear a mouth guard. If the droplets stick to the wall or floor of a room after you cough, the risk of infection is over, because they are usually not thrown back into the air. Theoretically, tuberculosis bacilli can survive for a long time in dust, but here too the risk of infection is extremely low.

Bovine tuberculosis (pathogen Mycobacterium bovis) practically no longer exist in Germany. Nevertheless, tuberculosis can get through M. bovis still occur as a reactivation of an earlier infection. In many poor countries, e.g. in parts of Africa or South America, however, tuberculosis infections still occur through ingestion of infectious dairy products.

Usually, people are infected at a time when it is not (yet) known that the carrier is suffering from infectious tuberculosis. The prerequisites for an infection usually include a certain amount of pathogen, sufficient duration and intensity of contact, as well as a corresponding susceptibility of the contact person. Therefore, not every contact necessarily means infection.

Particularly contagious are patients in whom tuberculosis bacteria can be found microscopically in the coughed up mucus (sputum). This is almost always the case with cavernous pulmonary tuberculosis, since the pathogens can be coughed up into the environment when connected to a draining bronchial branch (bronchus) and can then be inhaled by people in the immediate vicinity.

Contact persons who have an immune deficiency, for example from the HIV virus (AIDS) or as a result of chemotherapy against an existing tumor disease, are particularly at risk of infection. Underweight people also have an increased risk of infection, as undernourishment and malnutrition also affect the immune system
The body's defense system consists of three functional circles:
(1) Bone marrow as a place where immune cells form.
(2) Various central immune organs such as thymus (imprinting T lymphocytes) and lymphatic organs near the gut (for imprinting B lymphocytes).
(3) Secondary lymphatic organs such as the spleen, lymph nodes and tonsils (tonsils).
A distinction is made between the so-called humoral defense (via the body fluids containing antibodies and factors from the so-called complement system) and the cell-mediated defense (with B and T cells, macrophages, antigen-presenting cells, granulocytes, etc.).
weaknesses. For this reason, when treating these tuberculosis patients, attention is paid to a high-calorie (high-calorie) diet.

Notification requirement & environmental investigation

According to the Infection Protection Act, every tuberculosis requiring treatment must be reported to the responsible health department as soon as possible. This then determines the closer contact persons (such as family members, friends, acquaintances, work colleagues, etc.) and determines in which period and in which cases an infection could have occurred (so-called environmental examination). The environmental examination is carried out with the help of a tuberculin skin test and / or an x-ray of the lungs. The first thing to do is to do the tuberculin skin test, and if the result is positive, an X-ray is taken. In the case of the tuberculin skin test, a positive reaction can usually only be expected 6-8 weeks after infection. Even in the case of the development of tuberculosis that requires treatment, it takes some time to show abnormalities in the X-ray image. If there is no evidence of an active disease at the time of the examination, follow-up examinations are therefore carried out at certain time intervals.

Chemoprophylactic treatment

In the case of fresh contact, an infection can be prevented in small children and people with a weakened immune system (especially HIV patients) by chemoprophylactic treatment with isoniazid (see also "Therapy"). If an infection has already taken place (positive tuberculin skin test), after excluding an active disease, the necessity of chemoprevention should be considered. This is usually done with isoniazid for nine months. This can prevent the progression of an infection into an active disease with a high probability.

Behavioral measures

The most effective measures to prevent infection are quick and reliable diagnostics, efficient treatment and the immediate isolation of potentially infectious patients. This also requires responsible health behavior from all of us. For example, a cough that lasts longer than three weeks should be clarified by a doctor. Many diagnoses of tuberculosis are delayed by the fact that the patients - often despite pronounced symptoms! - Seek medical treatment very late, although in the meantime they may endanger their surroundings. It is of course crucial that the treating physicians then also think about tuberculosis (differential diagnosis).

The most important hygiene measures include adequate room ventilation, patient behavior (cough hygiene, mouth protection) and personal protective measures for the medical staff. A functioning tuberculosis control also requires good training and education of all those involved, as well as cooperation between the public health service, laboratories, clinical and private practice areas. Reliable reporting data enable a reaction to new epidemiological developments (increase in resistance, population groups at risk). In addition, active case-finding measures such as the above-mentioned environmental examination, the check-up of people with latent tuberculous infection or previous tuberculosis and the examination of risk groups help to detect cases of illness at an early stage and thus break the chains of infection.

So far no vaccination protection

An active vaccination with M. bovis-BCG (BCG vaccination; Bacillus Calmette Guérin), a live attenuated vaccine, does not provide reliable protection. It only helps to prevent severe tuberculosis courses in childhood (meningitis, miliary tuberculosis) and is therefore still mainly carried out in countries with a high incidence of tuberculosis. In this country, due to the decline in the number of illnesses and the resulting unfavorable risk-benefit ratio, it has not been recommended by the Standing Vaccination Commission at the RKI (STIKO) since 1998. Another problem is that positive tuberculin skin test results in BCG-vaccinated children are difficult to interpret. Initial clinical studies with newer, more potent vaccines are promising, but routine use is not expected for a few years.