TB prevention therapy: A game changer for ‘END TB STRATEGY’

Tuberculosis has been one of the deadliest diseases worldwide for centuries. According to Global TB Report 2023, an estimated 10.6 million people fell ill with TB globally and 1.3 million people suffering from TB died globally in 2022. India carries a high burden of TB, with an estimated 27% of the global TB cases and 31% of global deaths due to TB cases. This causes substantial economic loss in terms of loss of lives, workdays and income. United Nations Sustainable Developmental Goals (UN SDG) aimed at ending the TB epidemic by 2030. India is one of the signatories of the UN SDG and has committed to End TB by 2025, five years ahead of the SDG timeline.

Dr. Chhavi Gupta, Senior Consultant, Infectious disease, Yashoda Super Speciality Hospital, NCR, talks about the importance of TB Prevention Therapy. Currently the focus is of the National TB control program is active case detection and treatment, however, targeted treatment of persons at risk of developing active TB disease is a crucial component of the End TB Strategy. Hence, the TB Preventive Treatment (TPT) program has been launched to decrease the latent TB reservoir, preventing the development of active TB and its spread in the community. Every year World TB Day is celebrated on 24^th March and this year’s theme is “Yes We Can End TB”.

Dr Gupta while talking to Medlarege, shed light on the TB Prevention Therapy.

What is latent TB and Tuberculosis infection?

Latent TB or Tuberculosis infection is scientifically defined as a state of persistent immune response to prior-acquired Mycobacterium tuberculosis antigens without evidence of clinically manifested active TB. People who have been exposed to TB bacteria inhale them, the immune system prevents these bacteria from growing, and bacteria remain dormant in the lungs of an individual for a long time. People with latent TB do not exhibit symptoms, the load of TB bacteria is very low, and hence it does not spread in the community. However, they can be carriers of TB bacteria. However, at any point in life especially in people with weakened immune systems like diabetes, or immunocompromised patients, TB bacteria may become active, resulting in Tuberculosis disease. Now this active TB bacteria load is very high and can easily spread from one person to another. The transition phase from LTBI to active TB infection can linger long and even during the initial period of active TB, the patient may be unaware of the illness; during this period there is a high chance of spread of active TB bacteria.

What is the current burden of Latent TB?

According to estimates, almost 33% of people worldwide have latent tuberculosis, while in India; the estimated prevalence is 31%.

What is Tuberculosis Preventive Therapy (TPT)?

TB Preventive therapy consists of one or two anti-tubercular drugs given to persons with a history of exposure to TB or those who are infected with TB (latent TB or TBI) and are at higher risk of developing active TB than the general population to prevent the development of active TB disease.

How does TPT work?

 According to available data, 51% of people having latent TB will gradually develop TB disease throughout their lives depending upon their immune status. TPT eliminates the dormant TB bacteria inside the body before it can develop into active TB and damage the organs. However, it will work only if active TB is ruled out in the concerned person. The goal is to reduce TB transmission in the community to have a significant impact on human health

Who should take TPT?

All household contacts of active pulmonary (lung) TB, immunosuppressed patients and patients on dialysis are eligible for TPT after ruling out active TB.

How TPT should be taken?

TPT should be taken only after being prescribed by the medical practitioner. It consists of one or two pills to be taken daily for the defined duration as recommended by the medical practitioner. It does not involve major side effects.

How does TPT help in TB elimination?

The available studies have shown that TPT reduces the risk of TBI converting to active TB by 60-70%.  Hence it will help in reducing the burden of TB and also halts the transmission of TB in the community.