Tuberculosis has broken out in a school in Baden-Württemberg. Four students are ill, at least 109 people have already been infected with the disease. In Germany, the disease is easily treatable, but still die in this country every year about 100 people. How dangerous the infection can be and why a vaccine is not recommended in Germany, explains the immunologist Stefan Kaufmann.
ZEIT ONLINE: Mr. Kaufmann, we rarely hear in Germany at all of tuberculosis cases. Now quite a lot of people are affected at once. Are you surprised?
Stefan Kaufmann: Yes and no. More than 100 infections in one go, that's a very high number. At the same time, it is no surprise to me that tuberculosis still occurs in Germany. According to the Robert Koch Institute, there were about five and a half thousand cases last year. Worldwide, the disease is still a big problem. There is no pathogen that kills more people.
Stefan Kaufmann, Director of the Max Planck Institute for Infection Biology in Berlin © David Ausserhofer / MPIIB
ZEIT ONLINE: How does the disease spread?
Kaufmann : Tuberculosis is relatively easy to transmit by droplet infection. When a person with the disease has coughed, the virus spreads in the air. Anyone standing nearby can pick up the germs by inhaling. They enter the lungs and settle there in the alveoli. There they are eaten by the body's own cells and begin to multiply exponentially. The immune system tries to destroy the pathogen. This is a particularly robust Mycobacterium. Instead of destroying them, the immune system usually bunkers the pathogens. They are then kept in check, so to speak, so that no further symptoms such as night sweats, loss of appetite and weight loss and especially cough arise.
ZEIT ONLINE: That is, a person can transmit the disease only if it broke out with her?
Businessman: Yes. Typically, individual infections remain undetected for a long time. Only months and sometimes years later it comes only to the onset of the disease. That then suddenly infected more than a hundred people, is rather unusual. In the case of Bad Schönborn, there must have been one person who brought the disease to school and started the whole avalanche. Maybe someone who has changed classes frequently. That would explain the high number of infections. It may also have been two people who have brought the pathogen.
ZEIT ONLINE: What happens now to the people who have had the symptoms?
Kaufmann: First they are isolated, they should not enter the school or other public areas. How strictly this is handled, ie whether a child may still see the parents, for example, the doctor has to decide individually. The treatment then takes several months. There are given different drugs. The key question is whether the germ is resistant to the strong antibiotics or not. If he starts on the medication, one can go out after a few months of a complete cure. Especially if the disease is detected early, the lung damage is so low that it does not play a clinical role.
ZEIT ONLINE: How exactly do the mycobacteria of tuberculosis harm the lungs?
Kaufmann: If the pathogen in the lungs is shed by the immune system, this is protective at first. However, as the immune system weakens, the pathogen and bunker response spreads. It creates the shadows, which one can see on the X-ray picture of patients. In these areas, the lung functions are then very limited.
ZEIT ONLINE: Does that mean the disease breaks out when the immune system is weak?
Kaufmann: Exactly. This is why tuberculosis is the leading cause of death among people living with HIV in Africa. Because HIV damages the immune system. Even old people are particularly at risk. And infants under the age of five whose immune system is not yet fully developed.