What is tuberculosis?
Tuberculosis (TB) is a contagious disease caused by a bacterium called Mycobacterium tuberculosis (affects any organ in the body except the nails and hair, usually the lungs). It is spread by air from one person to another and usually requires prolonged or intimate exposure to a person with active tuberculosis in order to be transmitted. Wu Hongnian, Department of Thoracic Surgery, Fuzhou Pulmonary Hospital
Tuberculosis bacteria in sputum
This is a tuberculosis colony in a petri dish
Tuberculosis bacilli under the electron microscope
What are the symptoms of tuberculosis
Symptoms may vary from person to person.
Common symptoms include:
Weakness or fatigue
Poor appetite
Weight loss
Fever and/or night sweats
Other specific symptoms of TB disease may include:
Chronic cough
Chest pain
Coughing up blood
How is tuberculosis spread?
Tuberculosis is transmitted only from a patient with active tuberculosis. When he or she coughs, sneezes, laughs, sings or speaks, the tuberculosis bacteria in droplets of sputum from the nose, mouth or lungs of a person with active tuberculosis are released into the air. Most of the tuberculosis bacilli are spread by coughing. These tiny droplets containing tuberculosis bacteria can be inhaled and infect people. Usually the infected person is someone who is in the same space as the patient and has been in the same space for an extended period of time. Simple contact in a large open area or by handling objects contaminated by a person with TB is not contagious.
Transmission of tuberculosis bacteria
What is latent TB?
In most people exposed to TB and infected with TB, the body is able to repel the bacilli and blunt them, making them inactive, even though they are still alive in the body and may later become active. This is called latent TB infection. Because latent TB patients have no symptoms, they appear to
Do not feel sick
they do not spread TB to others
usually have a positive skin test (called the Mantoux test, tuberculin test, PPD)
are likely to develop TB in the future if they do not receive preventive anti-TB treatment during their lifetime.
There are many patients with latent TB who do not develop TB disease again. Tuberculosis bacteria can remain inactive for a lifetime. But on the other hand, especially in people with a weak immune system, TB can become active and become infectious.
What is an active TB patient?
If the immune system is unable to stop the growth of TB bacteria, the bacteria may become active. TB disease can occur when the number of active bacteria in the body increases. After exposure to TB bacteria, some people develop TB disease quickly, while others only get the disease when their immune system is low for some reason. Infants and children, especially under the age of four, may be more susceptible because of their immature immune systems.
Other people who are susceptible to TB infection include:
People with AIDS or who are carriers of the virus
Drug abusers, drug users
Patients with silicosis
Diabetics
Patients with cancer of the head or neck
Patients with leukemia or Hodgkin’s
Severe kidney disease
Low weight children
Certain specific treatments.
For example: corticosteroid therapy, chemotherapy or drug therapy for tumors
Anti-rejection therapy after organ transplantation
How tuberculosis is diagnosed
An intradermal tuberculin sensitivity test must be done. For those who may have had a history of exposure to tuberculosis, an intradermal tuberculin susceptibility test is performed immediately and repeated within 8 to 10 weeks. The second test at 8 to 10 weeks is very important because that is the length of time that the TB bacilli have been growing in the body. This simply means that they are infected, but it does not mean that they have active TB disease. Other tests include a chest CT or a pathological biopsy of the area suspected of having TB. In most cases, medication to prevent TB disease is necessary to prevent current and future TB disease and to prevent existing TB bacteria from becoming active.