Tuberculosis (TB) is an infectious disease caused by mycobacteria. The disease, also known colloquially as consumption, usually affects the lungs, but can in principle also affect other organ systems. According to WHO estimates, one person dies of tuberculosis every 20 seconds worldwide. The infectious disease must therefore be classified as a global health emergency.
Below you can find out more about the causes, symptoms and treatment of tuberculosis and which doctor treats tuberculosis.
Tuberculosis is caused by bacteria from the Mycobacteriaceae family. In addition to the most common pathogen Mycobacterium tuberculosis, these also include the species Mycobacterium bovis and Mycobacterium africanum. Transmission usually occurs through people suffering from open pulmonary tuberculosis. The focus of tuberculosis in the lung tissue is connected to the respiratory tract so that pathogens can be released into the environment via the exhaled air.
Infection is usually aerogenic, i.e. via very fine droplets containing pathogens that are released when coughing, speaking or sneezing. Whether infection then occurs depends on the one hand on the duration, frequency and closeness of contact with the infected person. On the other hand, the amount of pathogens inhaled and the state of health of the exposed person play a decisive role in the infection. In principle, tuberculosis infection is also possible through the consumption of unpasteurized milk from infected cattle. However, the cattle population in Germany and Central Europe is largely tuberculosis-free, so the risk of infection is very low here.
In the first stage of tuberculosis infection, the latent tuberculosis stage, there are no symptoms.
The tuberculosis pathogens are surrounded by cells of the immune system, the so-called T lymphocytes. This leads to the formation of inflammatory and nodular changes, also known as tubercles or granulomas. These tubercles are found in the lungs in more than 80 percent of all cases of the disease. If the adjacent lymph nodes are involved, doctors also speak of a primary complex. Most tuberculosis patients still show no symptoms in this second stage of the disease. However, some sufferers have a slight fever and a dry cough or cough with little yellowish-green sputum. It is also not uncommon to experience so-called B symptoms with heavy sweating at night, loss of appetite and weight loss.
Severe courses of the disease with hemoptysis (coughing up blood ) and chest pain usually only occur in patients with a weakened immune system. In people with a healthy immune system, the foci of inflammation become encapsulated after one to two weeks. This results in closed tuberculosis, where there is no risk of infection. However, the pathogens are only encapsulated and have not completely disappeared. In the case of immunodeficiency, the foci of inflammation can break open, allowing the pathogens to enter the environment via the respiratory tract. This infectious form of the disease is also known as open tuberculosis. As part of this reactivation, the mycobacteria can spread in the body and manifest themselves in other organs.
In addition to pulmonary tuberculosis, there are other forms of the disease:
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An initial suspected diagnosis is often made by taking a medical history and performing a physical examination. In particular, contact with infected persons as well as previous suspicions or a known initial infection can be taken as clear indications of a disease.
However, pathogen detection is essential to confirm the diagnosis. For this purpose, pathogen-containing material is obtained from saliva, gastric juice, bronchial secretions or, in the case of urogenital infestation, from urine and examined in microbiological diagnostics. Ziehl-Neelsen staining can be used to identify mycobacteria. Acid-fast bacteria can be stained with a special solution in this procedure, whereas other bacteria remain colorless. However, the detection limit is very high, meaning that many bacteria must be present for reliable pathogen detection. A negative result with Ziehl-Neelsen staining therefore does not definitively rule out a tuberculosis infection, and a positive result is also not considered conclusive. A positive bacterial culture with antibiogram, on the other hand, is considered proof of a tuberculosis infection. In addition, a further molecular biological procedure, the so-called polymerase chain reaction (PCR), can be carried out to confirm the diagnosis.
The course and prognosis of tuberculosis depend on several factors. On the one hand, the patient's immune status influences the prognosis. People with a weakened immune system can develop so-called miliary tuberculosis. In this case, small foci of the disease form in the lungs and various other organs. Typical symptoms include a severe feeling of illness, high fever, headaches and shortness of breath. If left untreated, almost all patients with miliary tuberculosis die. With adequate treatment, the mortality rate is still around ten percent.
Another dreaded complication that significantly worsens the prognosis is tuberculous meningitis. Although this is extremely rare, accounting for less than one percent of reported cases of tuberculosis in Germany, it is usually fatal. On the other hand, the course of the disease is influenced by the time of discovery. The earlier the diagnosis is made, the better the prognosis.
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