Tuberculosis

Tuberculosis
Image taken from CDC.

Introduction

Tuberculosis (TB) is a communicable disease caused by bacteria Mycobacterium Tuberculosis. This is among oldest known pathogens. About one-third of the worlds’ population has latent TB, which means people have been infected by TB bacteria but are not yet ill with the disease and cannot transmit the disease.  Tuberculosis is one of the oldest known human diseases which are still one of the major killers in the world. TB has many manifestations, affecting bone, the CNS and most of all organ system but mainly it affects Lungs and respiratory system.

Global Scenario

TB has no barriers and no stopping agent. It occurs in all parts of the world. In 2015, Asia had 61% new cases and Africa with 26% new cases. TB is among the top 10 leading causes of death world wide. According to WHO, in 2015 1.8 million people died of TB and 10.4 million people fell ill.

Signs and Symptoms

TB bacteria mostly affect lungs and can cause symptoms such as:

  1. A bad cough that lasts for 3 weeks and longer.
  2. Pain in the chest.
  3. Coughing up blood or sputum
  4. Weight loss
  5. No appetite
  6. Weakness or fatigue
  7. Chills
  8. Fever
  9. Sweating at night

Testing and Diagnosis

There are mainly two kinds of testing used to detect TB. The TB skin test (TST) and TB blood test are the main kind. These tests only tell that a person has been infected with TB, they does not tell whether it is Latent TB or diseased TB. Hence, further tests such as X-ray, sputum test, Culture test are necessary to confirm.

Treatment for Latent TB infection

Drugs Duration Interval Comments
Isoniazid 9 months Daily Preferred treatment for:

·        Persons living with HIV

·        Children aged 2-11

·        Pregnant Women (with pyridoxine/vitamin B6 supplements)

Twice weekly* Preferred treatment for:

·        Pregnant Women (with pyridoxine/vitamin B6 supplements)

Isoniazid 6 months Daily
Twice weekly*
Isoniazid and Rifapentine 3 months Once weekly* Treatment for:

·        Persons 12 years or older

Not recommended for persons who are:

·        Younger than 2 years old,

·        Living with HIV/AIDS taking antiretroviral treatment,

·        Presumed infected with INH or RIF-resistant M. tuberculosis, and

·        Women who are pregnant or expect to become pregnant within the 12–week regimen.

Rifampin 4 months Daily

*Use Directly Observed Therapy (DOT)

Note: Due to the reports of severe liver injury and deaths, CDC recommends that the combination of rifampin (RIF) and pyrazinamide (PZA) should generally not be offered for the treatment of latent TB infection.

Treatment for diseased TB

TB bacteria become active and the immune system can’t do anything then the latent TB turns out to be active or diseased TB. This is the one that makes the person sick and spreads the bacteria from person to person. Diseased TB patients must be treated soon and take drugs as prescribed. This TB can be treated by taking several drugs for 6-9 months. Some are given below. (3)

Isoniazid (INH)

Rifampin (RIF)

Ethambutol (EMB)

Pyrazinamide (PZA)

 

 

 

 

 

 

 

References

  1. Smith I.Mycobacterium tuberculosis Pathogenesis and Molecular Determinants of Virulence. Clinical Microbiology Reviews. 2003;16(3):463-496. doi:10.1128/CMR.16.3.463-496.2003. – NCBI (.pdf  download)
  2. WHO
  3. Medical News Today
  4. CDC
  5. WebMD