Tuberculosis: Symptoms, Causes, Treatment

Tuberculosis (TB; Tbc) – colloquially called consumption – (synonyms: Koch’s disease; Tb; Tbc; tuberculosis; ICD-10 A15.-: Tuberculosis of the respiratory organs, bacteriologically, molecularly or histologically confirmed) is an infectious disease caused by the pathogens of the Mycobacterium tuberculosis complex. The Mycobacterium tuberculosis complex includes Mycobacterium tuberculosis, M. africanum, M. bovis, M. microti, M. canetti, and others. In 80% of cases, the disease is confined to the lungs (pulmonary form); only 20% manifest extrapulmonary (affect other organs). Typical sites of manifestation of extrapulmonary tuberculosis are the genitourinary and intestinal tracts, extrathoracic lymph nodes, and bones and joints. One speaks of “active tuberculosis” when symptoms of a florid disease can be detected. Typical signs of activity include: positive pathogen detection in smear or by histology. An “open” TB is present when the pathogen reaches the outside naturally through body secretions such as sputum (sputum) or urine. In these cases, the patient is considered highly infectious and must be isolated immediately! Tuberculosis is now considered the most common infectious disease leading to death in adolescents and adults and is the leading cause of death in HIV-infected individuals. It is one of the 10 most frequent causes of death worldwide. Pathogen reservoir: Humans are currently the only relevant pathogen reservoir for M. tuberculosis and M africanum. For M. bovis, humans and cattle, as well as some wild animals, constitute the reservoir. Occurrence: Tuberculosis is prevalent worldwide and, along with HIV/AIDS and malaria, is one of the most common infectious diseases worldwide. About one third of the world’s population is said to be latently infected with tuberculosis pathogens, with about 5-10% of infected adults developing tuberculosis requiring treatment in the course of their lives – provided they are immunocompetent.The situation is particularly problematic in sub-Saharan Africa, where the high HIV infection rates give a particular boost to the tuberculosis epidemic. Around 85% of all new cases of tuberculosis live in Africa (especially sub-Saharan Africa), Southeast Asia and the western Pacific region… According to the Robert Koch Institute (RKI), Somalia, Eritrea, Syria, Serbia and Kosovo are considered high-prevalence countries. In 2014, more than 9.6 million people worldwide contracted tuberculosis, and 1.5 million died from it, although the disease is easily treatable with medication. 95% of cases occur in developing countries. About 85% of all new cases of tuberculosis live in Africa (especially sub-Saharan Africa), Southeast Asia, and the Western Pacific region. Contagiousness (infectiousness or transmissibility of the pathogen) is not as easy as with other airborne diseases (such as measles, varicella). Whether infection occurs depends on several factors:

  • Frequency and duration of contact with a sick person.
  • Amount and virulence (“infectiousness”) of the inhaled pathogens.
  • Susceptibility of the exposed person

Transmission of the pathogen (route of infection) occurs via droplets produced by coughing and sneezing and absorbed by the counterpart through the mucous membranes of the nose, mouth and possibly the eye (droplet infection) or aerogenically (through droplet nuclei containing the pathogen (aerosols) in exhaled air). Human-to-human transmission: Yes. The incubation period (time from infection to onset of disease) or latency period to disease is months to several years. Sex ratio: In childhood, boys are affected slightly more often than girls. Between the ages of 25 and 34, women are affected more frequently than men. In older age, the disease occurs more often in men. Frequency peak: There is an age peak in children under 5 years, especially one-year-olds are affected here. In adults, there is a peak in frequency in the 30-39 year old group and one in those over 69 years of age. Clinical classification of tuberculosis according to stage of infection:

  • Latent tuberculous infection: initial infection with successful containment of the pathogens, but persistence in the organism; the most common form in people with intact immune systems (80% of cases).
  • Primary tuberculosis: in this case, a so-called primary complex (local tuberculous focus of inflammation with involvement of the regional lymph nodes) develops directly from the initial infection; organ manifestation after initial infection. Primary tuberculosis causes in many cases no symptoms;
  • Postprimary tuberculosis: reactivated tuberculosis (80% as pulmonary tuberculosis, 20% as extrapulmonary tuberculosis), temporal latency may be several decades.

Classification of tuberculosis according to localization:

  • Pulmonary tuberculosis (synonym: pulmonary tuberculosis) – 80% of cases.
  • Extrapulmonary tuberculosis:
    • Abdominal tuberculosis – in about 55-60% of cases as lymph node tuberculosis.
    • Urotuberculosis – here especially the genitourinary tract (with mostly unilateral kidney infestation / renal tuberculosis).
    • Neurotuberculosis – rather rare; 5-15% of extrapulmonary tuberculosis; in immunosuppressed patients in 15% of all cases in the form of tuberculous meningitis.
    • Tuberculous spondylitis/vertebral inflammation (synonym: spondylitis tuberculosa) – affects especially the lower thoracic and lumbar spine; in up to 50% of cases following pulmonary or miliary tuberculosis (dense seeding of miliary tubercles in the lungs)

The incidence (frequency of new cases) is 5.3 cases per 100,000 population per year. Course and prognosis: Tuberculosis occurs in 80% of cases as pulmonary tuberculosis (pulmonary tuberculosis). For extrapulmonary spread (“outside the lungs”) see above under “Classification of tuberculosis according to localization”. The course of the disease depends on how early it was recognized and treated. In the majority of cases it heals without consequences. If the disease is diagnosed late or if the immune system of the affected person is weakened, severe lung and organ damage can occur. If left untreated, the disease takes a long and severe course. The lethality (mortality in relation to the total number of people suffering from the disease) is approx. 2.7 % and increases with age (6.8 % in people over 69 years of age). Note: Tuberculosis has the second largest burden of disease of all infectious diseases after seasonal influenza. The so-called BCG vaccination (tuberculosis vaccination) has not been recommended by the STIKO (“Ständige Impfkommission”) since 1998. This is also in line with the recommendations of the WHO (“World Health Organization”), which has suggested that no general BCG vaccination should be carried out in populations where the risk of infection with tuberculosis is less than 0.1%. In Germany, the direct detection of the pathogen is reportable by name according to the Infection Protection Act (IfSG), as well as subsequently for the result of the resistance determination; in advance also for the detection of acid-fast rods in sputum (sputum). Furthermore, reportable are:

  • The treatment, the disease as well as death from tuberculosis, even if bacteriological evidence is not available;
  • Refusal of therapy or a discontinuation of treatment;
  • Also resistance developments under therapy should be reported to the health department.