Tuberculosis infection can be classified into active TB and latent TB. At least one-third of the population across the globe is considered to be infected with tuberculous bacteria. This is known as latent tuberculosis and this type of infection does not show any symptoms. It is not transmitted to other individuals either.

A Tuberculin test conducted on the skin of the infected individuals will give a positive result.

But in only 5 to 10 percent of such infected individuals, will the mycobacteria multiply and result in an active TB disease with symptoms. This is named as active tuberculosis or TB disease. A person with active TB can transmit the infection to others.

Active tuberculosis can be grouped into two- Pulmonary tuberculosis and Extrapulmonary tuberculosis.

• Pulmonary tuberculosis - usually tuberculosis is seen as pulmonary TB which affects the lungs.

This is further grouped into two, based on sputum examination - sputum positive TB and sputum negative TB.

- Pulmonary tuberculosis in which the sputum examination shows mycobacterium tuberculosis is called sputum positive tuberculosis and this type has the highest chance of getting transmitted to another individual.

- Pulmonary TB in which the sputum test does not show tuberculosis bacteria is sputum negative TB. This type usually will not get transmitted to another individual. This is often diagnosed by a chest X-ray or clinically by a doctor.

• Extrapulmonary tuberculosis- This is the Tuberculosis which affects organs other than the lungs, such as intestines, bones, skin, lymph nodes, brain, meninges ( covering of the brain) etc. This type of tuberculosis does not spread to other individuals.

Based on the response to TB treatment, tuberculosis can also be classified into monoresistant tuberculosis, MDR tuberculosis (Multidrug Resistant), XDR TB (Extensively Drug-Resistant TB).

If the mycobacterium expresses resistance to one of the first line drugs, it is called mono resistant tuberculosis. If the disease does not respond to more than one type of first-line antitubercular drugs, it is called MDR tuberculosis. If the resistance is seen for more than two drugs and also for at least one injectable drug, this is called XDR tuberculosis.

Symptoms of Tuberculosis

• Cough - Long standing cough which is present for more than two to three weeks should be investigated

• loss of weight

• chest pain

• loss of appetite

• long-standing fever

• evening rise of temperature or night sweats

• blood tinged sputum

• swellings on the body

In case of long-standing back pain, tuberculosis of spine should be ruled out.

Diagnosis

Various advanced diagnostic techniques are available presently in the government sector to detect TB. The most basic test for tuberculosis screening is sputum microscopy test (AFB staining). This staining technique can demonstrate tuberculous bacteria under a microscope. Investigations like X-Ray and CT scan of the chest can also help the doctors diagnose pulmonary tuberculosis. Latest diagnostic technology like CBNAAT is used to diagnose TB from sputum and even other body fluids.

FNAC test (Fine needle aspiration cytology) where tissue is aspirated with a needle from a swelling or biopsy test can be used to diagnose TB in case of body swellings and enlarged lymph nodes. Ultrasound scan and MRI scanning can also help in diagnosing tuberculosis of abdomen and brain. Test conducted on fluids aspirated from the spine using a needle is used to diagnose TB meningitis. Tests on aspirated fluids from the covering of the lungs(pleural tap) or covering of the abdominal organs (ascitic tap) can lead to the diagnosis of extrapulmonary Tuberculosis.

Biopsy test of the organs involved in tuberculosis is considered as the confirmatory test for TB.

For the diagnosis of TB in children, Mantoux test is often used. A tuberculin protein product is injected beneath the skin of forearm and skin changes are noted after 2 to 3 days.

When children who came in contact with adults suffering from active tuberculosis come with symptoms of TB, a positive Mantoux test in such children is considered significant. To aid the diagnosis of childhood tuberculosis in such cases, a blood test report and chest X-ray are also useful.

Sputum culture test and drug sensitivity test(DST) are also done in patients when required. The state TB lab is equipped with facilities for all such advanced tests.

Treatment of tuberculosis, drugs and preventive methods will be discussed in the next session