Tuberculosis

From Tuberculosis Wiki

Tuberculosis (TB) is a curable, preventable disease that is the second deadliest infectious disease in the world, behind COVID-19.[1] TB is caused by the bacteria Mycobacterium tuberculosis. The bacteria usually infect the lungs, but they can infect any part of the body.[2]

Transmission[edit | edit source]

Tuberculosis is airborne and is most commonly spread in congregate or other close-quarters settings via coughing, speaking, or singing.[3][1] TB is spread primarily through sustained close contact between family members, friends, coworkers, and schoolmates.[3] TB cannot be transmitted via skin-to-skin contact, sharing food or drink, touching bed linens or toilet seats, sharing toothbrushes, or kissing.[3]

Forms[edit | edit source]

Infection with tuberculosis leads to latent TB, which does not produce any symptoms and is not contagious.[4] Latent TB produces a positive result on TB skin tests and IGRA blood tests, and it produces a normal chest x-ray, negative sputum smear, and negative molecular-based test.[4] It is estimated that one in four people in the world have latent TB.[1] The risk of infection developing into disease is highest in the first two years after infection (5%),[1] and can increase again later in life due to weakening of the immune system.[4] The risk is much higher for those living with HIV, with a risk of re-activation of up to 10% per year.

Development of tuberculosis disease is usually caused by Drug-susceptible Tuberculosis. However, some strains of M. tuberculosis are resistant to some or many of the drugs used to treat the disease, leading to Multidrug-resistant Tuberculosis, Pre-Extensively Drug-resistant Tuberculosis, and Extensively Drug-Resistant Tuberculosis.

Symptoms[edit | edit source]

When a TB infection develops into TB disease, the person will experience symptoms. These may be mild for many months, so it is easy to spread TB to others without knowing it. Common symptoms of TB include prolonged cough (sometimes with blood), chest pain, weakness, fatigue, weight loss, fever, and night sweats. The symptoms people get depend on where in the body TB becomes active. While TB usually affects the lungs (pulmonary TB),[5] it can infect other parts of the body (extrapulmonary TB).[6] Extrapulmonary TB is usually not contagious.[3]

Demographics[edit | edit source]

Babies and children are at higher risk of infection.[7] Certain conditions can increase a person’s risk for tuberculosis disease, such as diabetes (high blood sugar), having a weakened immune system (for example, HIV or AIDS), being malnourished, and tobacco use.[7]

Vaccination[edit | edit source]

Main article: Vaccination

There is one vaccine available for tuberculosis, the Bacille Calmette-Guérin Vaccine. It is relatively old technology with low efficacy, and it only prevents the development of TB disease, not infection. It is typically given at birth to prevent severe forms of disease found in very young children.

Diagnosis[edit | edit source]

Main article: Diagnosis

There are multiple tools for diagnosis of tuberculosis infection and disease. TB skin tests and IGRA blood tests can be used to diagnose latent TB infection. The WHO-recommended route for diagnosing tuberculosis disease and drug resistance is rapid molecular testing, which includes GeneXpert and TrueNat, which are both polymerase chain reaction (PCR) tests. However, due to cost, sputum smear microscopy and culture-based drug susceptibility testing, which are considerably slower and less accurate than molecular testing, remain common.

Treatment[edit | edit source]

Main article: Treatment

Treatment of tuberculosis is usually managed by taking combinations of drugs, which may be pills and/or injections, for many months. In some cases, surgery is performed on damaged tissues. In many areas, treatment follows the DOTS protocol, in which health care providers directly observe patients taking their pills.

HIV and TB[edit | edit source]

Among people living with HIV, tuberculosis is the leading opportunist infection and most common immediate cause of death.[8] People living with HIV are 18 times more likely to develop TB disease than people without HIV, and 8% of all people with TB are co-infected with HIV.[9] In 2020, one third of the 40 million people living with HIV were infected with TB, and 90% died within months without proper treatment.[8] Public investment in tuberculosis and HIV-related interventions from 2000 to 2020 has prevented nearly 12 million TB deaths in people with HIV.[9]

References[edit | edit source]

  1. ^ a b c d Global Tuberculosis Report 2023 (Report). World Health Organization. 2023. ISBN 9789240083851.
  2. ^ "Basic TB Facts". Centers for Disease Control and Prevention. 20 March 2016.
  3. ^ a b c d "How TB Spreads". Centers for Disease Control and Prevention. 3 May 2022.
  4. ^ a b c "Latent TB Infection and TB Disease". Centers for Disease Control and Prevention. 11 December 2020.
  5. ^ "Signs and Symptoms". Centers for Disease Control and Prevention. 14 February 2023.
  6. ^ Lee, JY (April 2015). "Diagnosis and treatment of extrapulmonary tuberculosis". Tuberc. Respir. Dis. 78 (2): 47–55. doi:10.4046/trd.2015.78.2.47. PMC 4388900. PMID 25861336.
  7. ^ a b "Tuberculosis General Information Fact Sheet". Centers for Disease Control and Prevention. 28 October 2011.
  8. ^ a b Krishnan, Vidya (2022). "9". Phantom Plague: How Tuberculosis Shaped History. New York: PublicAffairs. p. 172. ISBN 9781541768468.
  9. ^ a b "Fact Sheet - World Tuberculosis Day 2022" (PDF). UNAIDS. 24 March 2022.