Tuberculosis (TB) is an infection that is spread through the air. It most commonly infects your lungs. Two billion people (a third of the world's population) are thought to be infected with the TB bacteria. Most of these people will not know they have been infected, but about 1 in 10 may develop active TB at some time in their lives.
While the rates of tuberculosis are much lower in developed countries, such as New Zealand, it is still a major cause of lung disease. It can reappear as active disease many years after first contracting the TB bacteria, Mycobacterium tuberculosis. While TB usually infects the lungs, other organs and parts of the body can also be involved.
How is TB spread?
TB is spread through coughing, sneezing or spitting. The bacteria are carried into the air and people nearby can breathe them in through their mouths and noses.
TB can stay inactive in someone’s body for many years before it develops. This is called latent tuberculosis infection. Even though you feel well and healthy, the doctor may still advise treatment to make sure you do not develop TB disease. Read more about latent TB.
Who is most at risk of getting TB?
Those at greatest risk include:
- People in close contact with someone who has a known case of TB. Most children get TB from an infectious adult within their immediate or extended family.
- People living in institutions, including refugee camps and immigration centres, prisons, rest homes and mental health facilities.
- People regularly coming into contact with cows, deer, possums and certain animal products are at risk of getting bovine TB. This is very rare in New Zealand. The most likely source of exposure to bovine TB is drinking unpasteurised milk from an infected cow or handling an infected animal carcass.
You cannot get TB from clothes, drinking glasses, eating utensils, toilets or other surfaces where a TB patient has been, or from shaking hands with them.
What are the symptoms of TB?
Symptoms of TB depend on which part of the body is affected. TB of the lungs is by far the most common type, and symptoms include:
- ongoing cough (lasting 3 weeks or longer), coughing up blood in your spit
- weight loss, poor weight gain or loss of appetite (not feeling like eating)
- fever, sweating a lot at night
- chest pain when you cough
- feeling weak, tired and unwell.
How is TB diagnosed?
If you have been around someone who has TB, you should go to your doctor for tests. There are two tests that can be used to help detect a TB infection: a skin test called a Mantoux test, or blood test.
- The Mantoux skin test used to be the most common test. A small needle is used to put some testing material, called tuberculin, under your skin. In 2 to 3 days, you return to the health care worker, who will check to see if there is a reaction to the test. Read more about the Mantoux skin test.
- Increasingly, a blood test (known as Quantiferon gold) is used to test for TB infection. This blood test measures how your immune system reacts to the bacteria that cause TB.
- In addition, other tests such as a chest x-ray and a sample of sputum (phlegm that is coughed up from deep in the lungs) may be needed.
How is TB treated?
TB is curable. However, the bugs that cause TB are strong and it can take a long time for them to die. Active TB (when there are symptoms) is treated with a combination of antibiotics for at least 6 months. A combination of different antibiotics is used to prevent the bacteria becoming resistant. Examples of antibiotics used to treat TB include isoniazid, rifampicin, ethambutol and pyrazinamide.
- It is very important if you have TB to take your medication regularly and finish the course of medicine. If you stop taking the antibiotics too soon, you can become sick again; if you do not take the drugs correctly, the bacteria that are still alive may become resistant to those antibiotics.
- TB that is resistant to antibiotics is harder and more expensive to treat.
- In some situations, local health department staff meet regularly with patients who have TB to watch them take their medications. This is called directly observed therapy (DOT). DOT helps the patient complete treatment in the least amount of time.
If you have TB, here are a few things you can do to take care of yourself and protect your family and friends.
Take your medication
Taking your medication and finishing the entire course is the best way to protect yourself and others from TB. When you stop treatment early or miss doses, TB bacteria have a chance to develop mutations that allow them to survive despite you taking TB medication. The resulting drug-resistant strains are much more difficult to treat.
Healthy eating and exercise
In addition to taking your medicines, you can help your body fight the infection by eating healthy foods, getting enough sleep and some exercise. Many people lose weight because of the infection. If you are losing too much weight, eat balanced meals with enough protein and calories to help you keep weight on.
Mental health and wellbeing
People often feel embarrassed about having TB and worried that other people will find out about it. Also, it is easy to feel isolated and alone because you cannot go to work, school or public places until you can no longer infect other people. If you are feeling depressed or have a low mood, tell your doctor.
Reduce the spread
It usually takes a few weeks of treatment from when you start your TB medication before you're not contagious anymore. In the first 3 to 4 weeks, you can reduce the spread of infection by:
- staying home and not going to work or school
- avoiding sharing a room with others
- wearing a surgical mask when you are around others
- covering your mouth when you sneeze, cough or laugh
- airing or ventilating your room, because TB spreads more easily in closed spaces.
If you have latent TB (no symptoms), your doctor may advise you to take medication to reduce your chance of getting active TB. By preventing latent TB from becoming active, you also won't spread TB to anyone else.
The BCG (Bacillus Calmette-Guérin) vaccine helps protect against severe forms of TB by helping your immune system fight against it. In New Zealand, the BCG vaccine is not recommended for the general population because the rates of TB are quite low in many parts of the country. BCG vaccination is recommended for babies or children less than five years of age if they have a higher risk of getting TB. Read more about the BCG vaccine.
Tuberculosis (TB) HealthEd, New Zealand
Tuberculosis Immunisation Advisory Centre, University of Auckland, NZ
Tuberculosis disease Ministry of Health, NZ
Tuberculosis (TB) Auckland Regional Public Health Service
Tuberculosis NHS choices
- Tuberculosis Immunisation Advisory Centre, Univeristy of Auckland, NZ
- Guidelines for tuberculosis control in New Zealand, 2019, Ministry of Health, NZ
- Antituberculosis drugs New Zealand Formulary
- Temporary cessation of BCG vaccination until further notice, Sept 2016, Ministry of Health, NZ