What exactly is tuberculosis?

For this article, research was done into Tuberculosis, better known by the abbreviation TB. This article explains what TB exactly is. Various sub-topics are examined: the clinical picture, the risk groups and risk factors, the spread, prevention and treatment of the disease.

Clinical picture

Tuberculosis is caused by an infection with the bacteria of the Mycobacterium tuberculosis complex. Active tuberculosis develops in 1015% of infected patients. In 80% of these patients this happens within 2 years. In the other cases it takes longer, sometimes decades. The incubation period therefore varies from 8 weeks to lifelong. In patients who are positive for the HIV virus, the development is faster.
A distinction is made between secondary pulmonary tuberculosis and secondary extrapulmonary tuberculosis. Secondary pulmonary tuberculosis is the most common form. This form is divided into open and closed tuberculosis. This form of tuberculosis occurs in the lungs. Secondary extrapulmonary tuberculosis is mainly localized in the skeleton (vertebrae and joints), the kidneys, genitals, brain, adrenal glands, lymph nodes and the skin.
Tuberculosis has no typical symptoms. The patient often suffers from fatigue, lethargy, emaciation, subfebrile temperature and night sweats. Pulmonary tuberculosis usually involves a persistent productive cough and possibly haemoptysis (coughing up blood from the airways). Tuberculous spondylitis can manifest itself not only by back pain, but also by a prolapsed abscess, while tubercular lymphadenitis usually manifests itself by painless swelling of the glands in the neck. Hematuria may be the only symptom of renal tuberculosis. Complaints that may occur with Bovine tuberculosis are chronic diarrhea and intestinal cramps. Bovine tuberculosis can also be localized in the lung and is then clinically indistinguishable from pulmonary tuberculosis due to M. tuberculosis.


Approximately 1.6 million patients die from tuberculosis each year. The disease is the largest cause of death among adults. In the Netherlands, the incidence of tuberculosis is approximately 10 per 100,000, of which half of the patients are of foreign origin.

Risk groups

  • Asylum seekers
  • Other immigrants from countries with a high tuberculosis prevalence
  • Detainees
  • Family members, caregivers, partners and other contacts of infectious source patients
  • Former patients (not treated or inadequately treated)
  • Drug addicts
  • Illegals
  • Seafarers
  • Homeless people


Risk factors

  • High incidence of the disease in your area
  • Infection with HIV (reduced resistance)
  • Malnutrition



Humans are the reservoir for tuberculosis, except for Bovine tuberculosis. Cattle is the most important host for this. After coughing, sneezing, speaking or singing, infected sputum droplets can dry into droplet nuclei of approximately 5 ┬Ám that remain suspended in the air for a longer period of time and are inhaled by the new patient. In moist warm air, survival in droplet nuclei for hours is possible. In pus or sputum container for several days. Primary infection with M. bovis occurs through drinking unpasteurized milk from cows with udder tuberculosis.
Finally, the injured skin or mucous membrane can form a portal through contact with contaminated material. Closed pulmonary tuberculosis and extrapulmonary tuberculosis are almost never contagious. In open pulmonary tuberculosis it is assumed that the infection period begins when coughing symptoms begin. After 3 weeks of adequate treatment, the patient is no longer contagious, unless it concerns resistant bacteria.


The BCG vaccine protects against tuberculosis, but vaccination with this vaccine gives no guarantee. In the Netherlands, vaccination only takes place for children under the age of twelve, one of whose parents comes from a country with a high tuberculosis incidence. This is due to regular family visits. BCG vaccination should be considered by travelers going to an area with a high tuberculosis incidence for more than three months, especially when medical facilities in the area are limited. Other prevention focuses on the early detection of infected people. This is done by examining the risk groups.


About 4 to 8 weeks after the infection, a specific immune response is built up. Treatment of the infection is quite possible. The treatment always consists of an intensive phase (rapid reduction of bacterial load, lasts 2 months) and a follow-up phase that aims to sterilize the disease process (lasts 4 months). INH and rifampicin are prescribed for treatment. If the bacteria develop resistance, the follow-up phase must be extended or other means must be used. In exceptional cases, isolation is used.