TB disease occurs when TB bacteria become active. The active bacteria begin to grow and start to damage the lungs or other parts of the body.

Some people develop TB disease soon after infection, while others develop TB disease later when their immune system becomes weak and they progress from latent TB to TB disease.

Latent TB is when the bacteria in the body are “asleep” and this means the person has the TB bacteria in his/her body but is not sick, does not have symptoms and cannot spread the infection.

Tuberculosis may last for a lifetime as an infection, never developing into disease.

TB disease

When a person with TB disease of the lungs or throat coughs, sneezes, speaks, or sings, the bacteria get into the air. Persons who breathe in the air containing these TB germs can become infected. Early treatment can prevent TB from spreading to other people.

Anyone who has come into contact with a person who has TB of the lungs or throat is at risk for getting TB infection, which may later develop into TB disease. This is more likely to happen in people with weakened immune systems. It is not possible to catch TB disease or latent TB infection from drinking glasses, cutlery, crockery, sheets, clothes or the telephone.

Latent TB infection

People with latent TB infection cannot pass the infection onto other people.

TB disease

Symptoms of TB depend on where in the body the TB bacteria is growing.

TB disease in the lungs may cause:

• a bad cough that lasts longer than two weeks

• pain in the chest

• coughing up blood or phlegm.

Other symptoms of TB disease may be:

• weakness or fatigue

• weight loss

• no appetite

• chills

• fever

• > sweating at night.

Latent TB infection

Latent TB has no symptoms.

Diagnosis of TB

TB Disease

The diagnosis of TB disease is made with medical assessment and help of various tests.

A chest x-ray is done to look for any damage to the lungs.

It is confirmed when Mycobacterium tuberculosis is grown from sputum and or fluid from the lungs.

TB in other parts of the body is confirmed on growing the bacteria from the site of disease. This could be from for urine, gastric fluids, blood or body tissue.

Latent TB infection

Tests to diagnose latent tuberculosis include:

• Tuberculin skin test (Mantoux test). A small amount of purified protein – taken from dead TB bacteria – is injected under the top layer of the skin, on the forearm. A small lump may form at the injection site over the next few days and you will need to return to your doctor or nurse 3 days later to have this assessed. The size of your lump – measured in millimetres – will indicate whether or not you have a latent TB infection.

• “Quantiferon” TB Test – a blood test which is an alternative to the skin test.

Sometimes repeat testing is needed to check if TB exposure has caused the infection.

Many people with TB infection never develop TB disease.

TB disease

• Some people develop TB disease soon after becoming infected (within weeks), before their immune system can fight the TB bacteria.

Latent TB

• People who have latent TB may get sick years later, when their immune system becomes weakened for another reason and they progress from latent TB to TB disease.

TB disease

• People with TB disease in the lungs or throat who have persistent coughing, coughing up blood, breathing problems, or flu-like symptoms can be infectious.

• People with symptomatic TB in the lungs or throat may be infectious until they have taken their TB medications for at least two weeks.

Latent TB infection

• People with latent TB infection are not contagious.

SA Tuberculosis Services is responsible for monitoring the follow-up and treatment of all cases of TB disease in South Australia.

Clinicians should notify SA Tuberculosis Services of any person suspected of having TB.

Prevention of TB