What is it about ?
Tuberculosis (TB) is a contagious infectious disease caused by the bacteria Mycobacterium tuberculosis or Koch’s bacillus, named after the German bacteriologist who discovered it in 1882. In the past, tuberculosis was known as “consumption” or “consumption”, the two terms describing the state of extreme thinness of the body. undernourished patients.
Tuberculosis can affect all tissues and organs, but only pulmonary tuberculosis is contagious. The bacteria are found in the expectorated mucus. If the infected person does not cover their mouth when they cough, they may project small droplets into the air which will be inhaled by others.
Not all infected people get sick. In 85 to 90% of infected people, the natural defenses are sufficient not to fall ill. They overcome contamination without outside help. In some, the bacteria remain in the body, without them being sick or contagious to others. This is called latent tuberculosis.
However, latent tuberculosis can become active when the “carrier’s” immune system weakens. A number of at-risk groups are more susceptible to it: asylum seekers, the homeless, alcoholics, drug addicts, migrants and travelers from countries where tuberculosis is common, detainees, people with been in contact with sick people such as healthcare providers, but also young children, the elderly, adolescents, people with weakened immune systems (such as people with HIV) or people taking immunosuppressive drugs.
What is its frequency?
In 2017, tuberculosis was diagnosed in 8.6 out of 100,000 Belgian residents. In Flanders, 386 cases of tuberculosis were reported that year. Its frequency is three times higher in large cities and ten times higher among the main groups at risk (homeless, detainees, asylum seekers). Of all tuberculosis infections, 95% occur in developing countries.
How to recognize it?
The signs of the disease can be very general: fatigue, listlessness, loss of appetite (anorexia), weight loss, mild fever and, at a later stage, night sweats. When the lungs are involved, a persistent cough develops with pain on breathing and coughing up bloody mucus.
Apart from the lungs, tuberculosis mainly affects the lymph nodes, bones, central nervous system and urinary tract. In the case of bone tuberculosis, one or more vertebrae are often affected, which causes increasing back pain. When the intestines are affected, stomach pain and diarrhea can occur. The lymph nodes may swell, especially in the neck, armpits and groins. At the level of the central nervous system, a encephalitis and an meningitis can occur. In people with a very weakened immune system (AIDS, cancer, etc.), the bacteria can reach the bloodstream and thus spread throughout the body. This is called miliary or disseminated tuberculosis. This condition can be fatal.
How is the diagnosis made?
Tuberculin test (or Mantoux test)
This test involves injecting a small amount of a solution containing a piece of protein from the bacteria into the skin. If you have been infected in the past, you will see a small lump appear around the injection site. A positive tuberculin test result does not necessarily mean that you are sick. In most people who inhale the bacteria, the immune system will overcome the infection.
In contrast, the “tuberculin shift” (ie an old negative reaction, but a positive reaction to the last test) is an important indicator because it is a sign of recent contamination. The test is done in all people who have been in close contact with someone with TB, eg. classmates, staff of an institution with an infected resident, colleagues, …
The test is not 100% reliable. Sometimes it gives false-positive results. In this case, a lump forms despite the absence of tuberculosis. Sometimes it can also give false-negative results: i.e. that the person does not develop a reaction when they are indeed infected.
People who received the vaccine BCG may also develop a false positive reaction to the tuberculin test.
The test can never be 100% sure that a person is sick; further tests should be done to confirm the diagnosis. The test is primarily a diagnostic aid.
There is now a new test: the IGRA Quantiferon blood test. This is carried out on a blood sample and therefore does not require any injection into the skin. Like the traditional tuberculin test, it cannot distinguish between active and latent tuberculosis.
Analysis of expectorated mucus
Staining and culture of a sample of expectorated mucus, taken three days in a row. Staining makes it possible to visualize the germs directly under a microscope. The result is available in a few days. Culture confirms the diagnosis, but takes 4-6 weeks. Culture is also possible for other products, such as blood, urine, tissue samples, cerebrospinal fluid, etc.
Imaging exams
Radiological examination: an x-ray of the lungs, vertebrae, etc. may reveal characteristic lesions.
What can you do ?
You can hardly avoid contamination. Most of the time, you don’t know you’ve been in contact with someone who has TB. When you cough, remember to cover your mouth to limit the spread of bacteria in the air.
It is essential to take all the prescribed medications on a regular basis and always at the same time, without stopping the treatment before the end. All bacteria must be eliminated from the body. Otherwise, the disease can resurface. Not to mention the risk of developing resistance, i.e. that residual bacteria become unresponsive to certain antibiotics and are therefore much more difficult to treat.
What can the doctor do?
In principle, antibiotics can completely cure TB patients. They need to take 3 to 4 medicines, known as anti-tuberculosis drugs, for at least 6 months.
There is a vaccine, which unfortunately is not very effective and which mainly protects against serious complications. This is why vaccination is reserved for groups at risk.
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