Tuberculosis(TB)

 

 Tuberculosis, MTB, or TB (short for tubercle bacillus) is a common, and in many cases lethal, infectious disease caused by various strains of mycobacteria, usually Mycobacterium tuberculosis.^[1] Tuberculosis typically attacks the lungs, but can also affect other parts of the body. It is spread through the air when people who have an active TB infection cough, sneeze, or otherwise transmit their saliva through the air.^[2] Most infections are asymptomatic and latent, but about one in ten latent infections eventually progresses to active disease which, if left untreated, kills more than 50% of those so infected.

One third of the world's population is thought to have been infected with M. tuberculosis,^[3] with new infections occurring at a rate of about one per second.^[3] In 2007, there were an estimated 13.7 million chronic active cases globally,^[4] while in 2010, there were an estimated 8.8 million new cases and 1.5 million associated deaths, mostly occurring in developing countries.^[5] The absolute number of tuberculosis cases has been decreasing since 2006, and new cases have decreased since 2002.^[5] The distribution of tuberculosis is not uniform across the globe; about 80% of the population in many Asian and African countries test positive in tuberculin tests, while only 5–10% of the United States population tests positive.^[1] More people in the developing world contract tuberculosis because of compromised immunity, largely due to high rates of HIV infection and the corresponding development of AIDS.

T-Spot TB Test.

Spot the hidden danger

T-SPOT. TB assay- Equally useful for the diagnosis of latent (LTBI) and active TB disease

• T SPOT TB Test has sensitivity of 95.6%.
• T SPOT TB Test uses the RDI antigens, ESAT-6 & CFP 10, which ensure it does not cross react with the BCG vaccine & most environmental mycobacteria.
• T SPOT TB Test has specificity of 97.1%.
• T SPOT TB Test detects extra pulmonary TB.
• T SPOT TB Test is the most accurate test available for the diagnosis of latent TB infections (LTBI).
• T SPOT TB Test is based on pioneering ELISPOT technology- the world’s first and only approved technique to directly measure effector T cell function.

 

A revolutionary blood test to diagnose latent TB infection (LTBI) & active TB Disease of both pulmonary and extra pulmonary regions with unmatched sensitivity and specificity.

This test is based on the measurement of effector T-Cells that have been specifically activated against Mycobacterium Tuberculosis antigens ESAT-6 & CFP 10, eliminates cross-reactivity to BCG & most environmental mycobacteria. This provides the T- SPOT. TB test with unique sensitivity & greater specificity.

• 
  
• US Approved (FDA)
• European Approved (CE)
• Listed in US CDC (Centre for disease Control) guide lines
• Best healthcare innovation award winning technology
• Over 170 published studies
• Has been successfully used all over the world 

The classic symptoms of active TB infection are a chronic cough with blood-tinged sputum, fever, night sweats, and weight loss (the latter giving rise to the formerly prevalent term "consumption"). Infection of other organs causes a wide range of symptoms.

• Signs and symptoms:

 

About 5–10% of those without HIV, infected with tuberculosis, develop active disease during their lifetimes. In contrast, 30% of those coinfected with HIV develop active disease. Tuberculosis may infect any part of the body, but most commonly occurs in the lungs (known as pulmonary tuberculosis).Extrapulmonary TB occurs when tuberculosis develops outside of the lungs. Extrapulmonary TB may coexist with pulmonary TB as well.General signs and symptoms include fever, chills, night sweats, loss of appetite, weight loss, and fatigue, and significant finger clubbing may also occur.

•  Pulmonary:

If a tuberculosis infection does become active, it most commonly involves the lungs (in about 90% of cases).Symptoms may include chest pain and a prolonged cough producing sputum. About 25% of people may not have any symptoms (i.e. they remain "asymptomatic"). Occasionally, people may cough up blood in small amounts, and in very rare cases, the infection may erode into the pulmonary artery, resulting in massive bleeding (Rasmussen's aneurysm). Tuberculosis may become a chronic illness and cause extensive scarring in the upper lobes of the lungs. The upper lung lobes are more frequently affected by tuberculosis than the lower ones.The reason for this difference is not entirely clear. It may be due either to better air flow, or to poor lymph drainage within the upper lungs.

• Extrapulmonary:

In 15–20% of active cases, the infection spreads outside the respiratory organs, causing other kinds of TB.These are collectively denoted as "extrapulmonary tuberculosis". Extrapulmonary TB occurs more commonly in immunosuppressed persons and young children. In those with HIV, this occurs in more than 50% of cases.Notable extrapulmonary infection sites include the pleura (in tuberculous pleurisy), the central nervous system (in tuberculous meningitis), the lymphatic system (in scrofula of the neck), the genitourinary system (in urogenital tuberculosis), and the bones and joints (in Pott's disease of the spine), among others. When it spreads to the bones, it is also known as "osseous tuberculosis".a form of osteomyelitis. Sometimes, bursting of a tubercular abscess through skin results in tuberculous ulcer. An ulcer originating from nearby infected lymph nodes is painless, slowly enlarging and has an appearance of "wash leather".A potentially more serious, widespread form of TB is called "disseminated" TB, commonly known as miliary tuberculosis. Miliary TB makes up about 10% of extrapulmonary cases.

• Active tuberculosis

Diagnosing active tuberculosis based merely on signs and symptoms is difficult,as is diagnosing the disease in those who are immunosuppressed.A diagnosis of TB should, however, be considered in those with signs of lung disease or constitutional symptoms lasting longer than two weeks. A chest X-ray and multiple sputum cultures for acid-fast bacilli are typically part of the initial evaluation.Interferon-γ release assays and tuberculin skin tests are of little use in the developing world.IGRA have similar limitations in those with HIV.

A definitive diagnosis of TB is made by identifying M. tuberculosis in a clinical sample (e.g. sputum, pus, or a tissue biopsy). However, the difficult culture process for this slow-growing organism can take two to six weeks for blood or sputum culture. Thus, treatment is often begun before cultures are confirmed.

Nucleic acid amplification tests and adenosine deaminase testing may allow rapid diagnosis of TB. These tests, however, are not routinely recommended, as they rarely alter how a person is treated. Blood tests to detect antibodies are not specific or sensitive, so they are not recommended.
Latent tuberculosis

• Mantoux tuberculin skin test

The Mantoux tuberculin skin test is often used to screen people at high risk for TB.Those who have been previously immunized may have a false-positive test result. The test may be falsely negative in those with sarcoidosis, Hodgkin's lymphoma, malnutrition, or most notably, in those who truly do have active tuberculosis. Interferon gamma release assays (IGRAs), on a blood sample, are recommended in those who are positive to the Mantoux test.These are not affected by immunization or most environmental mycobacteria, so they generate fewer false-positive results. However they are affected by M. szulgai, M. marinum and M. kansasii.IGRAs may increase sensitivity when used in addition to the skin test but may be less sensitive than the skin test when used alone.




Reference :
http://en.wikipedia.org/wiki/Tuberculosis