Just a few years ago it was believed that TB was an old disease, and that it was no longer a problem in humans. But now because of such issues as drug resistance and HIV, it has become a major worldwide problem again. Worldwide more people die from the disease than from any other infectious disease. TB is an abbreviation of the word Tuberculosis and is how people often refer to the disease. It is caused by bacteria called Mycobacterium tuberculosis (M.tuberculosis).
The bacteria that usually cause the disease in humans, usually affect the lungs, but can affect other parts of the body. If you are infected with the bacteria you won’t necessarily become sick, because you can have either latent TB or TB disease. People with latent TB do not feel sick and do not have any symptoms.
It is estimated that about 40% of the Indian population is infected with TB bacteria, the vast majority of whom have latent rather than active TB.
India accounts for about a quarter of the global TB burden. Worldwide India is the country with the highest burden of TB. There are an estimated 79,000 multi-drug resistant TB patients among the notified cases of pulmonary TB each year. India is also the country with the second highest number (after South Africa) of estimated HIV associated TB cases. In 2016 an estimated 28 lakh cases occurred and 4.5 lakh people died due to TB.
In March 2017 the Government of India announced that the new aim with regard to TB in India was the elimination of TB by the year 2025.
Pathogenesis of Tuberculosis
When a person with TB of the lungs or throat coughs, sneezes, sings or talks, droplets containing the bacteria are released into the air. That is why people, who think they may be infectious, may often hold something over their mouth when they are near to other people. People working in a health clinic may also for this reason sometimes wear a mask.
The spread of TB is stopped by firstly finding the adults who have TB. Particularly in countries with a high burden of TB, awareness of TB must be raised so that people with symptoms of TB know they should get help.
People with TB disease must then be provided with effective TB treatment which means that they will no longer be infectious and can no long spread TB to other people. They will also usually then recover from being sick although the treatment for TB takes a long time.
Investigation: Some of the current TB tests take a long time to obtain a result, and some TB tests are not very accurate. The TB tests either have low sensitivity (the ability to correctly detect people with TB) and/or low specificity (the ability to correctly detect people who haven’t got TB).
If a TB test has low sensitivity, it means that there will be a significant number of “false negatives”, meaning that the test result is suggesting that a person has not got TB when they actually have. Similarly, a low specificity means that there will be a significant number of “false positives” suggesting that a person has TB when they actually haven’t.
The most accurate tests such as culture take a long time to do. Some tests are also very expensive and require complex laboratory facilities.
ADA (Adenosine Deaminase)
- ADA is found in all tissues highest activities in:
- T lymphocytes
- Monocytes - macrophages
- Marker for cellular immunity and cell-mediated hypersensitive reactions Activity is elevated in diseases eliciting a cell-mediated immune response.
- Increased serum ADA activities in infectious diseases.
- Micro organisms infecting mainly the macrophages, like tuberculosis.
Role of ADA:
The Role of ADA in the Early Diagnosis of pulmonary Tubercular diseases
- Total ADA is very sensitive 88 %
- X-ray -76%
- ESR -72%
- Sputum for AFB-NZ -63%
- Mantoux -61%.
Can be used to differentiate pulmonary TB from non-tubercular pulmonary disease.
The accuracy of the ADA assay was similar to that of the IFN-y assay in differentiating of TB from non-TB ascites. Because both material and human costs of the ADA assay are far less than those of the IFN-y assay, the former is probably the most appropriate diagnostic test for analysis of peritoneal fluid in resource-limited settings.
Advantages of Erba ADA Kit:
- Erba ADA is easy to use
- Improved precision
- More convenient and flexible
- Normal ranges have been established for the Erba method
- Liquid Stable reagent
- Excellent precision
- Can be automated
“Basic TB Facts”, CDC www.cdc.gov/TB/topic/basics/default.htm
JP Cegielski, “The relationship between malnutrition and tuberculosis: evidence from studies in humans and experimental animals”, Int. J. Tuberc. Lung Dis. 2004;8:286-98
“Basic TB Facts”, CDC www.cdc.gov/TB/topic/basics/risk.htm
“Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings 2005”, CDC, 5 www.cdc.gov/tb/publications/guidelines/infectioncontrol.htm
“Get the Facts About TB Disease”, CDC www.cdc.gov/tb/publications/pamphlets/default.htm
Let's all contribute in making India TB Free by 2025