Tuberculosis pathogens

Third to AIDS and malaria, tuberculosis is the most widely spread infectious disease. Every year, three million people die of this disease, most of them in East Asia and Africa. But the increase in worldwide travel has also put the industrialized countries, which are less affected, at a greater risk from the pathogen. It is also alarming that more and more germs are appearing which are resistant to the previously reliable antibiotics. Although it is possible to vaccinate people for tuberculosis, the effectiveness is limited and there is a risk of serious side effects.

Tuberculosis bacteria are transmitted primarily by airborne droplets (from speaking, sneezing, coughing). The transmission occurs if there is close, longer-term contact with people suffering from open tuberculosis (infectious form of TB). This situation is found most often where people with open TB live together in close quarters, in families, shelters for the homeless or prisons. Healthy people with a strong immune system rarely become ill. The risk is greatest for people who suffer from poor nutrition and whose immune defences have been weakened. This is the reason why the majority of the cases of tuberculosis are in poor countries. However, the richer industrialized countries are also affected, although to a far lesser extent.

Tuberculosis treatment in Togo

The Immune Defence against Tuberculosis Bacteria

Whenever droplets carrying tuberculosis bacteria are breathed into the lungs, the pathogens allow themselves to be ingested by phagocytes and hide there like stowaways. This allows them to escape the immune defence for the moment and they cannot be reached by antibodies and other weapons. The tuberculosis bacteria have a trick which enables them to survive in the "stomach" of the phagocytes, otherwise a deadly environment: they cause digestive problems, so to speak, for the defence cell gluttons. The bacteria withdraw into hollow bubbles (vesicles) of the phagocytes, and the phagocytes are not able to destroy the vesicles on their own. As a sign of their infection, they display "wanted" posters of the pathogens on their surfaces. Special T helper cells (Th1 cells) then hurry to their aid and activate the phagocytes in order to accelerate their "digestion." Now the stowaways can be destroyed by aggressive substances. The phagocytes die in the process.

T Helper cells (model)

However, part of the bacteria frequently survive and infect other phagocytes. It is typical of tuberculosis that a number of phagocytes melt together and form a centre of inflammation which is completely encapsulated by T cells. A so-called granuloma forms which can also be seen in X-rays. The granuloma can survive for years in the human body. During this time, there is a risk of contagion from the infected person.

The granulomas can break apart again, especially in people whose immune systems have been weakened, and release tuberculosis bacteria. If they enter the blood or lymph systems, there is a risk that the pathogens will spread throughout the body and attack other organs. During this stage, we speak of open TB, and the infected person can spread the disease to others.

Incurable Tuberculosis. Before antibiotics were discovered, patients could only hope that their bodies would fight off the disease on its own. The doctors could do little more than prescribe rest, fresh air and regular meals. Tuberculosis remained a feared disease which claimed innumerable lives until the end of the Second World War.

Resistant to Antibiotics
As late as the 1970s, physicians believed that tuberculosis had been defeated in the highly developed industrialized nations. Mass X-ray examinations were stopped long ago in Germany, and a preventive vaccination has not been recommended for the general public for years. The number of cases of tuberculosis in this country is also relatively low. Yet there are still many countries in which tuberculosis is very common. The infection rate in the CIS is increasing dramatically.

In 2001, one million people in the CIS were incarcerated. In many prisons, virtually all of the inmates have been infected with tuberculosis bacteria.

The problem: without knowing it, immigrants can carry tuberculosis pathogens which are very difficult to treat. Some of the bacteria strains are resistant to a number of antibiotics.