Tuberculosis

Dr. Rathivika sundar, MBBS, MRCP (UK) fellowship in infectious diseases

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Introduction

Tuberculosis is an important infectious disease caused by the bacteria Mycobacterium Tuberculosis. Tuberculosis can affect any part of the body but the commonest organs affected are the Lungs (Pulmonary) and Lymph nodes (Lymphadenitis). The symptoms of Pulmonary Tuberculosis are cough, https://www.starhealth.in/blog/coughweight loss, night sweats, evening rise in temperature, loss of appetite and malaise. It is a contagious disease that spreads through the air from an infected person.

Tuberculosis categories

Tuberculosis is divided into two broad categories – Pulmonary and Extra-pulmonary Tuberculosis.

Your treating Physician may request standard tests and some specific tests for Tuberculosis. Standard tests include Blood counts, Chest X-ray, CT scan of the chest, Ultrasound scan, etc.

Tuberculosis tests and diagnosis

Some of the specific tests are:

• Sputum for Acid Fast Bacilli, in which three early morning samples of the sputum are checked for the presence of the bacteria.
• Gene Xpert is another specific test that can detect the presence of the bacteria and, in addition, give information regarding antibiotic resistance, which can help the treating doctor choose the right treatment for the patient.
• Cultures are also done in certain situations where the bacteria are grown from the sample collected. But Mycobacterium is a slow-growing bacteria, and culture growth can take about 4-6 weeks.
• Tuberculin skin test (Mantoux test) is also a diagnostic test for Tuberculosis. A 0.1 ml of Tuberculin purified protein derivative (PPD) is injected intra-dermally, and skin reaction is read between 14-72 hours. The diameter of the reaction is measured in millimetres.

The false-positive reaction can occur in the following:

1. Previous TB vaccination (BCG vaccine)

2. Infection with other types of Mycobacteria

Tuberculosis can spread through the blood to other organs. A severe form of Tuberculosis is called disseminated Tuberculosis or Miliary Tuberculosis. It comprises about 10% of Extra-pulmonary Tuberculosis. This is a life-threatening condition.

The Tuberculosis vaccine also called the BCG (Bacille Calmette Guerin) vaccine, is being administered to newborns as part of the mandatory vaccine schedule in India due to the high prevalence of Tuberculosis. It prevents the development of severe forms of the disease such as Tuberculous meningitis and Miliary Tuberculosis. This vaccine should be avoided in immunosuppressed people (Eg: HIV, chronic kidney disease, chronic liver disease) and during pregnancy.

Treatment for Tuberculosis is with a certain group of Anti-Tuberculous medicines, which are given for a prolonged duration (Around 6-10 months). The first line of Anti-Tuberculous medicines is Rifampicin, Isoniazid, Pyrazinamide and Ethambutol. The second line of Anti-Tuberculous medicines comprises certain specific antibiotics which are used when there is resistance to the first line of medicines. It is important to complete treatment for the prescribed duration to avoid developing resistance to the medicines.

What is Latent Tuberculosis?

Latent Tuberculosis is when a person has the bacteria, but their immunity can fight this microbe. Hence the person does not fall sick. The bacteria become inactive within the host and stays there for the entire lifetime. In certain situations, when this person’s immunity is reduced due to unknown factors, Latent Tuberculosis may become active and cause the disease.

The risk of infection can be reduced by following the below measures:

• Maintaining proper Hygiene
• Good ventilation
• Natural light
• Healthy diet
• Stop smoking
• Follow cough etiquette

Conclusion

Tuberculosis is one of the most misdiagnosed infectious diseases. This is due to the challenges of specific Tuberculosis tests, particularly in extra-pulmonary Tuberculosis. This is also a disease with a social stigma in developing countries, where it continues to exhibit a significant burden on the healthcare system.