Content Status where content has been uploaded and published on LMS.
TB is a notifiable disease in India, and TB notification has been made mandatory at the point of diagnosis since May 2012. This means that when a case of TB is diagnosed and/or put on treatment it is to be reported to the NTEP.
Drug resistance in Mycobacterium tuberculosis occurs when there is acquisition of mutations in genes that code for anti-TB drug targets or drug-activating enzymes.
Drug resistance in Tuberculosis (TB) occurs through two main mechanisms shown in the figure below.
Figure: Mechanisms or Types of Drug Resistance in TB
The mechanism of transmission of drug-resistant (DR) and drug-sensitive (DS) TB is the same i.e., via infectious aerosols.
Tuberculosis (TB) is an infectious, chronic, granulomatous disease caused by Mycobacterium tuberculosis. It usually involves the lungs but may affect any organ or tissue in the body.
The pathogenesis of TB in a previously unexposed immunocompetent individual is centred on the development of cell-mediated immunity. This confers resistance to the organism and results in the development of tissue hypersensitivity to tubercular antigens.
 Figure 1: Global Burden of DR-TB in 2019; Source: Global TB Report, WHO, 2020. |
In 2019, globally there were an estimated 4.65 lakh (~0.5 Million) Multi-drug Resistant (MDR)/ Rifampicin Resistant (RR) TB cases. Against the estimates, only about a third (~38%) were notified and received treatment. |
Pathogenesis of TB is a product of interaction between bacterial activity and immune responses in the host.
Generally, in a person with good cellular immunity, the clearance of Mycobacterium tuberculosis (Mtb) is quite good and the chances of developing the active disease are less.
Ventilation is an important determinant of airborne infections. Poor ventilation at a patient's residence or at a healthcare facility, will result in more risk attached for any airborne infections.
Poor Ventilation and Inadequate Air Circulation as Risk Factors for Tuberculosis (TB)
Overcrowding is the situation where people located within a given space are more than what is considered tolerable from a safety and health perspective. Generally in living/ dwelling areas an measure of 50 square feet is the minimum requirement for space per person; less than this is considered overcrowding.
Calculating the floor space per person: The number of persons in the household divided by the total area of the house gives the floor space per person.
Tuberculosis is transmitted mainly through the air via droplet nuclei generated when a TB patient coughs or sneezes.
It is estimated that every sputum smear-positive patient spreads the infection to 10 – 15 persons annually, if untreated..
Figure: Transmission of TB bacteria through air via droplet
Resources:
Environmental conditions have a huge role in the development of TB disease and are an important component of the epidemiological triad for TB disease.
The various environmental factors influencing TB are: