Affecting around 1.8 billion world’s population with 10 million active cases tuberculosis (TB) is an airborne bacterial infection caused by Mycobacterium tuberculosis, which is contagious and can spread from person to person.
It is usually spread through air, when the infected person coughs or sneezes out the bacteria. These bacteria, when inhaled by a healthy person, can get stuck on the lung tissue causing pulmonary tuberculosis. It can also affect other parts of the body like the brain, lymph nodes, kidneys, bones, and joints. Such a condition can be termed extrapulmonary tuberculosis.
The risk of infection due to TB is high for those who are in close contact with the infected person. The risk of getting infected is high in babies and young kids, people with chronic disorders like diabetes, people suffering from HIV/AIDS, and people who underwent organ transplants as this disease also spread to various organs of the body.
What are the stages of tuberculosis?
Based on the kind of infection caused by the TB bacteria and the spread of the disease, the stages of TB are:
Primary TB infection: It is the first stage of infection in which the immune system finds and captures the germs and destroys them. A few germs will survive and multiply but do not manifest any symptoms. In this stage, the person exposed to the disease will have a negative skin test and a normal chest X-ray.
Latent TB infection: In this stage, the immune system controls the spread by building a wall around the infected lung tissue. This stage does not manifest any symptoms and TB remains inactive throughout life. This stage shows a positive skin test and a normal chest X-ray.
Active TB disease: In this stage, there will be active signs and symptoms of the disease as the infection can no longer be controlled by the immune system. The germs spread all over the lungs and other parts of the body. This stage may happen after primary TB infection or it may happen after months of latent TB infection. The infected person will show a positive skin test and a positive chest X-ray.
What are the symptoms of tuberculosis?
The symptoms of a person affected with TB disease differs based on the stages of infection
- In the primary TB infection stage, there will be no symptoms but if any infection persists it may show symptoms like that of the flu
- Low fever
- Cough
- Fatigue
- In the latent stage, no symptoms are seen and the person does not fall sick
- In the active TB stage, many symptoms are seen and get worse in a few weeks. The symptoms include:
- Cough with mucus and blood
- Pain in the chest, while breathing and coughing
- Fever and coldness
- Sweating at nights
- Loss of appetite and weight
- Fatigue
How can tuberculosis be diagnosed?
A detailed medical history may be the first step in the diagnosis of TB, followed by a basic physical exam to check for swollen lymph nodes. Based on the observations a skin test or a blood test is recommended to diagnose the disease. A chest X-ray or CT scan can help to look for the signs of TB in the lungs.
TB skin test (TST): This test is also known as the Mantoux tuberculin skin test. The test is performed by injecting a small amount of tuberculin into the skin, and the reaction is observed within 48 to 72 hours. The test result depends on the size, swelling, and hard area of the injected site. A positive test result indicates the presence of TB infection, and a negative result indicates no latent or active TB infection.
TB blood test: It is also called the Interferon-Gamma Release Assay (IGRA) test or the QuantiFERON®-TB Gold Plus (QFT-Plus) test. A sample of the blood is collected and tested immune response of the bacteria is by measuring the interferon-gamma levels in plasma. A positive blood test result indicates either latent TB infection or Active TB disease, whereas a negative result indicates no TB infection. This test is recommended for a person who finds it difficult to wait for the skin test results and for those who have already received the BCG vaccine.
Some other tests may also be needed to further confirm the spread of the disease. They are:
Sputum test: A sample of your sputum is collected and tested for the presence of bacteria and the type of strain of TB present in it.
CB-NAAT test: Additional molecular testing of TB can be done by Cartridge Based Nucleic Acid Amplification Test (CB-NAAT) or Genexpert test to detect genetic mutations in the DNA of TB bacteria and its resistance to the rifampicin drug. The test is done using a sputum sample and the result can be generated on the same day.
Treatment for Tuberculosis
TB is treated with medications, taking care to take all the doses until the completion of the treatment followed by precautionary measures.
Vaccination for Tuberculosis
In some countries, a vaccine called Bacillus Calmette-Guerin (BCG) is given to children as a part of immunization to prevent meningitis (infection of the fluid membrane of the brain and spinal cord) and miliary tuberculosis (a serious form of TB).
Although TB is curable, it can be fatal if not treated. Based on the results of the above tests a healthcare provider plans the treatment regimen to treat the disease. Follow the instructions of your healthcare provider until all the symptoms of TB disease disappear and find yourself back to normal.
