What Is Tuberculosis?

Are you experiencing symptoms such as persistent coughs for more than 3 weeks or coughing up blood? Followed by chest pains, weakness, weight loss, fever, and night sweats? Then you might want to call your doctor immediately since these are the symptoms of tuberculosis, a bacterial infection that affects the lungs. Tuberculosis is a serious condition; however, it can be cured if it is treated right. 

Tuberculosis (TB) is a severe infectious disease that mostly affects the lungs. The bacteria that cause tuberculosis are transmitted from person to person through the air.1 To become infected by tuberculosis, it is enough to inhale only a few of these germs.1 However, tuberculosis is curable and preventable. 

Tuberculosis primarily affects adults at their most productive ages.1 But all age groups are at risk. More than 80% of the cases and deaths occur in low- and middle-income countries.1 Regardless, tuberculosis is a serious health condition, if untreated it might be fatal. 


Tuberculosis is a leading infectious cause of death worldwide.2 TB usually infects the lungs but it can also spread to other organs. TB infection is spread from person to person through air.1,2 As stated by the World Health Organisation (WHO), about 25% of the global population is estimated to have been infected with TB bacteria, however, most people will not go on to develop TB disease. Those who are infected but not ill with TB (yet) cannot transmit the disease.1 It has been identified that people infected with TB bacteria will have a 5-10% risk of developing the disease during the first 2-5 years after infection.3 For others, the immune response will eliminate the infection without leaving any trace of an immune response.3

Causes of tuberculosis

Tuberculosis occurs due to a bacterium known as Mycobacterium tuberculosis that is transmitted by the infected person while sneezing, coughing, spitting, or laughing4,5 and therefore via inhaling pathogenic droplets, Mycobacterium tuberculosis reaches the lungs. The successful transmission is dependent on the duration spent with Mycobacterium tuberculosis-infected individuals.6 However, people with weakened immune systems have a greater risk of getting infected with TB where even a single or a few bacteria might be enough to establish TB.7 For example, it has been identified that a person with HIV has a higher risk of developing TB and can have more severe symptoms compared with someone with a healthy immune system.8 

Signs and symptoms of tuberculosis

People with latent TB infection will experience no symptoms. However, people with tuberculosis that affects the lungs may have the following symptoms:

  • Persistent cough for 3 weeks or longer
  • Coughing with blood
  • Swelling in neck
  • Chest pain
  • Unexplained weight loss
  • Loss of appetite 
  • Night sweats
  • Fever
  • Chills

Management and treatment for tuberculosis

It is important to note that TB is a serious health condition that if left untreated can be fatal.5 Yet, TB is preventable and curable via taking antibiotics for several months (at least for 6-months). Drug-susceptible TB is generally treated with a standard 6-month course of antimicrobial drug1 provided with the support of your general practitioner since the patient could have difficulties with treatment adherence.1

To treat tuberculosis, it is crucial to diagnose the type of TB the individual is infected with. 

Here are two distinct types of TB: 

  • Latent TB - you are infected with TB; however, you are not experiencing any symptoms of TB9
  • Active TB - known as TB disease where this condition makes you sick and you can transmit the disease to others. It can occur in months or years after infection with TB bacteria 

Pulmonary TB:

This is the most common type of TB where the lungs are affected. An individual infected with pulmonary TB would have to undergo at least a 6-month course of combinational treatment, including 4 antibiotics (isoniazid, rifampicin, pirazinamide, ethambutol) for 2 months and continuation of 2 drugs (isoniazid and rifampicin) for further 4 months.

It might take at least 2 weeks before the individual will start to feel better and it will depend on the individual's overall health and severity of TB.1,5

Extrapulmonary TB: 

This is the type of TB that occurs outside the lungs meaning it can infect all other organ systems such as the central nervous system (brain).10 Extrapulmonary TB is often difficult to diagnose, especially in the absence of pulmonary tuberculosis. In 19% of cases, extrapulmonary TB is not associated with pulmonary tuberculosis.10 Standard drug therapy for extrapulmonary TB is the same as for pulmonary tuberculosis, but the duration of treatment will be longer (12 months). Further, if resistance to one or more first-line drugs exists, the treatment regimen should be adjusted.5,10

Multidrug-resistant TB: 

There is also something known as multidrug-resistant TB where some of the TB strains might be resistant to 2 or more antimicrobial treatments. The multidrug-resistant TB required a prolonged treatment regime where an antibiotic would be prescribed for at least 9 to 24 months depending on the strain.1,5  

Finish your treatment 

It is essential to complete a full treatment course even if the individual will start to feel better and does not experience any of the symptoms of TB. Ending the treatment too soon or skipping medication doses can let the bacteria that are still alive obtain resistance to drugs taken and result in more aggressive TB which would complicate further treatment. If the full course is completed by all standards, no further checks for TB will be required. 

Side effects

Some TB drugs (for example, isoniazid) may cause serious side effects such as nerve damage.5,11 For this reason, you will be prescribed vitamin B6 supplements (pyridoxine) to take alongside to reduce this risk.5 In addition, your liver will be examined before starting the treatment. In some exceptional cases, antimicrobial drugs (ethambutol) that are prescribed to treat TB may cause eye damage which can be serious therefore your vision will be tested before the beginning of the course. 

Rifampicin can also interact with other drugs, therefore it is crucial your doctor and healthcare providers know all the medications you are taking before starting tuberculosis treatment.5

It is important to contact your doctor when manifesting these symptoms during TB treatment: 

  • Being sick5
  • Yellowing of skin and the whites of eyes5
  • Tingling or numbness in hands or feet5
  • Blurred vision5
  • Skin rash5
  • High temperature5 


How is tuberculosis diagnosed

There are several tests available to diagnose depending on the type of suspected TB. However, the first test would involve a physical examination where the doctor would check your lymph nodes for swelling and use a stethoscope (a medical device that is used for listening to the internal sounds of a human or an animal) to listen to the sounds that your lungs make.5,12 

Subsequently, you will be referred to a skin test or a blood test where the doctor would inject a substance called tuberculin just below your skin on the inside of your forearm. Therefore, within 48 to 72 hours you would have to come back to your healthcare provider to check your arm for swelling around that area.12 A hard, raised, red bump means you may be infected with tuberculosis. The size of the bump determines whether the test results are significant.12

If your skin test is positive, you will be referred to do a chest X-ray or a CT scan. This may indicate white patches in the lungs that the immune system has protected from tuberculosis bacteria or indicate changes in the lungs caused by active tuberculosis.5,12

If a chest x-ray shows signs of tuberculosis, your doctor may take a sample of sputum (mucus produced when you cough). Samples will be tested for Mycobacterium tuberculosis.12

How can I prevent tuberculosis

After testing positive for latent TB, you must get the necessary treatment from your doctor to prevent active TB. Only active TB is infectious. 

Is there a TB vaccine

In some countries, for example in the UK, children are vaccinated with the anti-tuberculosis vaccine, Bacillus Calmette-Guérin (BCG), as part of routine immunisation programmes. BCG vaccination is only recommended on the NHS for babies, children, and adults under the age of 35 who are at risk of catching tuberculosis (TB).5 This is because there is no evidence of vaccine effectiveness on individuals that are over the age of 35. The BCG vaccine can only be given once in a lifetime. 

Who are at risk of tuberculosis

Those include:

  • People with a health condition that affects the immune system such as people with HIV, diabetes, or malnutrition1
  • People with treatments that weaken the immune system such as chemotherapy or biological treatments5  
  • People with poor health and poor diet due to lifestyle and other problems such as drug use or alcohol misuse, or homelessness5 

How common is tuberculosis

Anyone can get tuberculosis. As stated by the WHO, in 2021, an estimated 10.6 million people were infected with tuberculosis worldwide: 6 million men, 3.4 million women, and 1.2 million children. Tuberculosis is present in all countries and can occur in all age groups. But most importantly, TB is curable and preventable.

When should I see a doctor

You should see your doctor if you are experiencing symptoms such as fever, unexplained weight loss, night sweats, or a persistent cough.5 These are indicators of TB; however, it could result from other conditions. You must see your doctor if you have been exposed to someone who is infected with TB. 


Active tuberculosis can be dangerous if left untreated. However, modern treatments can prevent both symptoms and complications if detected early by a specialist. Therefore, if you are experiencing any of the TB symptoms, make sure to contact your doctor to receive an examination as soon as possible. 


  1. World Health Organization. (2022, October 27). Tuberculosis (TB). World Health Organization. Retrieved January 30, 2023. Available from: https://www.who.int/news-room/fact-sheets/detail/tuberculosis 
  2. Drain, P. K., Bajema, K. L., Dowdy, D., Dheda, K., Naidoo, K., Schumacher, S. G., Ma, S., Meermeier, E., Lewinsohn, D. M., & Sherman, D. R. (2018). Incipient and subclinical tuberculosis: A clinical review of early stages and progression of infection. Clinical Microbiology Reviews, 31(4). Available from: https://doi.org/10.1128/CMR.00021-18 
  3. Carranza, C., Pedraza-Sanchez, S., de Oyarzabal-Mendez, E., & Torres, M. (2020). Diagnosis for latent tuberculosis infection: New alternatives. Frontiers in Immunology, 11. Available from: https://www.frontiersin.org/articles/10.3389/fimmu.2020.02006/full 
  4. Sia, J. K., & Rengarajan, J. (2019). Immunology of mycobacterium tuberculosis infections. Microbiology Spectrum, 7(4). Available from: https://journals.asm.org/doi/full/10.1128/microbiolspec.GPP3-0022-2018 
  5. NHS. (2019, November 12). Tuberculosis (TB). NHS choices. Retrieved January 30, 2023, from https://www.nhs.uk/conditions/tuberculosis-tb/causes/ 
  6. Mathema, B., Andrews, J. R., Cohen, T., Borgdorff, M. W., Behr, M., Glynn, J. R., Rustomjee, R., Silk, B. J., & Wood, R. (2017). Drivers of tuberculosis transmission. The Journal of Infectious Diseases, 216. Available from: https://academic.oup.com/jid/article/216/suppl_6/S644/4589580 
  7. Andersen, P., & Scriba, T. J. (2019). Moving tuberculosis vaccines from theory to practice. Nature Reviews Immunology, 19(9), 550–562. Available from: https://www.nature.com/articles/s41577-019-0174-z 
  8. Katz, I. T., & Maughan-Brown, B. (2017). Improved life expectancy of people living with HIV: Who is left behind? The Lancet HIV, 4(8). Available from: https://www.thelancet.com/journals/lanhiv/article/PIIS2352-3018(17)30086-3/fulltext 
  9. Barry, C. E., Boshoff, H. I., Dartois, V., Dick, T., Ehrt, S., Flynn, J. A., Schnappinger, D., Wilkinson, R. J., & Young, D. (2009). The spectrum of Latent tuberculosis: Rethinking the biology and intervention strategies. Nature Reviews Microbiology, 7(12), 845–855. Available from: https://www.nature.com/articles/nrmicro2236#citeas
  10. Natali, D., Cloatre, G., Brosset, C., Verdalle, P., Fauvy, A., Massart, J.-P., Vo Van, Q., Gerard, N., Dobler, C. C., & Hovette, P. (2020). What pulmonologists need to know about extrapulmonary tuberculosis. Breathe, 16(4), 200216. Available from: https://breathe.ersjournals.com/content/16/4/200216 
  11. Combrink, M., Loots, D. T., & du Preez, I. (2020). Metabolomics describes previously unknown toxicity mechanisms of isoniazid and rifampicin. Toxicology Letters, 322, 104–110. Available from: https://www.sciencedirect.com/science/article/abs/pii/S0378427420300266 
  12. Mayo Foundation for Medical Education and Research. (2021, April 3). Tuberculosis. Mayo Clinic. Retrieved February 1, 2023, from https://www.mayoclinic.org/diseases-conditions/tuberculosis/diagnosis-treatment/drc-20351256
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Karina Silova

MSc Molecular Medicine and BSc Biomedicine, University of East Anglia, UK

My background is in key areas of biomedical research focusing on diseases and their molecular pathways to understand their root cause. I specialise in epigenetics and reproductive health; I am passionate about understanding diseases and helping to bridge the gap between medical science and the general public with accurate and understandable content while educating the public about health and diseases.

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