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Tuberculosis 

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Overview of Tuberculosis

Tuberculosis (TB) is a disease caused by the bacteria called Mycobacterium tuberculosis. The bacteria usually attack the lungs and cause pulmonary Tuberculosis (TB). But, it is not limited to the lungs and Tuberculosis (TB) bacteria can attack any part of the body such as the kidney, spine, and brain. If not treated properly, Tuberculosis (TB) disease can be fatal. Tuberculosis disease was once the leading cause of death in USA.

PrevalenceTuberculosis is a major cause of illness and death worldwide, especially in Asia and Africa. According to WHO estimates, globally, 9.2 million new cases and 1.7 million deaths from Tuberculosis (TB) occurred in 2006, of which 0.7 million cases and 0.2 million deaths were in HIV-positive people.1 Population growth has boosted these numbers compared with those reported by the World Health Organization (WHO) for previous years. More positively, the number of new cases per capita appears to have been falling globally since 2003, and in all six WHO regions except the European region, where the rates are approximately stable. If this trend is sustained, WHO estimates that Millennium Development Goal 6, to have halted and begun to reverse the incidence of TB, will be achieved well before the target date of 2015.

Mode of transmission of Tuberculosis: The mode of transmission of Tuberculosis (TB) is through the air from one person to another.

When a person with active Tuberculosis (TB) sneezes or coughs, he or she releases an aerosol with thousands of particles into the air surrounding him or her. The bacilli get distributed in the air and enter the breathing space of the other people in the vicinity when they breathe the air.

When a person breathes in tuberculosis bacteria (TB), the bacteria can settle in the lungs and begin to grow. From there, they can move through the blood to other parts of the body, such as the kidney, spine, and brain. Tuberculosis in the lungs or throat can be infectious. This means that the bacteria can be spread to other people.

Tuberculosis in other parts of the body, such as the kidney or spine, is usually not infectious. People with active Tuberculosis (TB) disease are most likely to spread it to people they spend time with every day. This includes family members, friends, and coworkers.

This is more so, in case of undiagnosed Tuberculosis, when the people living with them do not have any knowledge and hence are not taking any precautions.

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Diagnosis of Tuberculosis

Clinically a person with latent TB will not have any symptoms.

A person with active TB will have a

  • History of chronic coughing for more than a few weeks,
  • Blood in sputum,
  • Weight loss,
  • Loss of appetite,
  • Fatigue
  • Weakness.

Not all persons will have all of the symptoms. If a person has one or more of the symptoms and has any history of contact with anyone suffering from TB or has visited any place where TB is common, he or she needs to be sent for diagnostic investigations. This is for the safety of the person and also to prevent the spread of the infection to all other people surrounding him or her.

Given below are some of the investigations that are commonly done to diagnose TB.

Skin test: The skin test commonly used for testing for TB is the Mantoux test. It is also called the tuberculin sensitivity test or Purified Protein Derivative (PPD) test. It is the screening test for TB.

It is one of the inexpensive, portable and hassle free test making it very popular especially when the testing has to be carried out at remote places.

The testing material used is a TB antigen, Purified Protein Derivative (PPD). For this test, a standard dose of 5 Tuberculin units (0.1 mL) is injected intradermally and the area of injection is marked on the skin. After 48-72 hours the induration (bump) is measured. The size of the induration gives an idea of TB infection taking into consideration the risk factors of the person for TB.

The interpretation of the test is as follows.

Bump of 5 mm or greater is seen in persons

  • with weakened immune systems, such as those with HIV/AIDS,
  • who have been exposed to persons with active TB,
  • with fibrotic changes on chest X-rays/scans that are consistent with an old TB infection,
  • with organ transplants and other immunosuppressed patients (receiving the equivalent of >15 mg/day of prednisone for >1 month).

Bump of 10 mm or greater is seen in persons

  • Arriving from a foreign country with a high number of TB patients,

  • Who use injectable drugs,

  • Who live or work in high-risk environments, such as cities and crowded areas

  • Who work in laboratories, especially mycobacteriology

  • Children under the age of 4 years
  • Children and adolescents exposed to adults in high-risk environments.

Heaf test is another skin test, which was performed in the UK until 2005 after which Mantoux test has been adopted.

QuantiFERON-TB Gold is a recently approved test in USA, Europe and Japan. It provides equal if not more sensitivity as the Mantoux test, but is faster and the results are made available before 24 h and does not require a second visit like the Mantoux test.1 Also, it is a laboratory-based test and removes the error of recording and judgement as the measurement of the induration in the Mantoux test.

Chest X-ray: If the screening test gives a positive result, a chest X-ray is taken to confirm the lung findings.

Sputum examination: Sputum is examined microscopically after appropriate staining to visualize the bacteria.



Causes of tuberculosis

An immunocompromised host is a very good candidate for Tuberculosis (TB) infection and development of the active disease. HIV weakens the immune system and thus allows for the development of Tuberculosis (TB).

HIV and TB

 

Management of tuberculosis

Multi drug resistant tuberculosis
Like, all the other diseases, resistance to drugs has become one of the major concerns in the management of tuberculosis. 


TB world wide strategies
Directly Observed Therapy Strategy commonly referred as DOTS was a strategy launched by the WHO in 1995 to combat the spread of Tuberculosis (TB)

BCG Vaccine

Conclusion for Tuberculosis

Tuberculosis has been a worldwide problem that has been brought to control thanks to WHO’s DOTS and Stop Tuberculosis (TB) strategies and more aggressive surveillance methods. Although new multi-drug strains are emerging and new disease associations like HIV are throwing up new challenges for the health community, there is still hope that the fight against Tuberculosis (TB) will ultimately be won.

We can contribute to the fight by ascertaining proper hygiene and if we know of any patients on antitubercular therapy, ascertaining that they take the medication continuously as scheduled. This way Tuberculosis (TB) can be eradicated and make the world a better place to live in.

Written by: Healthplus24 team
Date last updated: September 27, 2012