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Middlesex-London Health Unit

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Active Tuberculosis (TB)

Inactive TB

Active TB

TB germs in your body are not growing TB germs in your body are growing
Positive TB skin test Positive TB skin test
No TB symptoms May be sick with TB symptoms
Chest X-ray shows no active TB  Abnormal chest X-ray or CT scan
No TB germs in sputum test Sputum test shows TB germs
Not contagious.  People cannot catch TB from you Contagious if TB germs are found in lung or airway.
Medication can be taken to prevent Inactive TB from becoming Active TB  Many medications must be taken to stop symptoms and the spread of TB

Table of Contents

What is active TB?

TB is an illness caused by the germ Mycobacterium tuberculosis. TB usually attacks the lungs but can also attack other parts of the body. The TB germ is spread through the air when a person sick with active TB, coughs, sneezes, or talks and someone else breathes the germ into their lungs. 

If a person breathes in the TB germ but the body’s immune system cannot stop the TB germ from growing, they can become sick with active TB. Active TB is also sometimes called TB disease. It is important to know that most people who breathe in the TB germ will NOT develop active TB. Only people who are sick with active TB can spread the TB germ to others. 

People with active TB must be treated with special TB medication so that they get better and do not spread TB to others. All cases of active TB must be reported to the health unit.

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TB Chest Xray


Man coughing

What are the symptoms of active TB?

Symptoms of active TB include:

  • cough 
  • coughing up blood or sputum (phlegm)
  • fever
  • night sweats
  • weight loss
  • tiredness

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How is active TB treated?

Treatment for active TB can take up to two years, but is usually taken for 6 months. Up to four different kinds of medicines must be taken daily. You may need to be isolated and stay away from other people at the beginning of the treatment so you do not spread TB to others. 

Active TB can be cured with the right combination of medicine. All TB medication is available free from the Middlesex-London Health Unit and all people with active TB are followed by a Public Health Nurse.  

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How do I find out if I have active TB?

The only way to know you have active TB is to get tested. A sputum sample and chest x-ray are the most common ways to diagnose active TB of the lung.  If you have an abnormal chest x-ray and symptoms of active TB,  your doctor may ask you to produce two or three sputum samples to send to a lab to look for TB germs. The TB skin test is also an important test for TB, but it is usually used to see if someone has inactive TB.

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Can I have active TB in other parts of my body?

Most people who breathe in TB germs never develop active TB. However, people who do become sick with active TB can develop disease in many different parts of the body other than the lungs. Common sites for active TB besides your lungs include lymph nodes, abdomen, bone and joints. If the active TB in other parts of the body is not treated, it may eventually spread to the lungs.

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Date of creation: February 26, 2013
Last modified on: March 21, 2018


1Public Health Agency of Canada and the Canadian Lung Association/Canadian Thoracic Society. Canadian Tuberculosis Standards, 8th Edition 2022