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
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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:
Host factors in TB disease are various factors/attributes of the host(person who is developing TB disease/infection).
The various host factors are as follows:
Mycobacterium tuberculosis (M. tuberculosis) belonging to the family Mycobacteriaceae cause Tuberculosis (TB).
These are rod shaped bacilli and require oxygen to survive (aerobic bacteria).
The following characteristics of these bacilli help them to survive in human body for a long time and resist the action of drugs:
Following are the risk factors that increase the chances of developing TB disease in an individual:
Figure: Risk factors for developing active TB
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TB notification rate is the number of TB cases notified over a specified time period for a specified population, usually per lakh. It indicates how many cases have been diagnosed and informed to the National TB Elimination Program.
It is mostly calculated annually, and the calculation formula is as follows:
Prevalence is an epidemiological measure of the proportion of a population with a disease or a particular health condition at a specific point in time (point prevalence) or over a specified period of time (period prevalence).
Tuberculosis (TB) prevalence refers to the number of people with TB that are present in a particular population at a given time. Calculation of the TB prevalence rate is shown in the figure below.
Incidence is an epidemiological measure of the occurrence of new cases of a disease in a population over a specified period of time. Tuberculosis (TB) incidence is the number of new cases of active TB disease during a certain time period (usually a year), and is better expressed as a rate, as shown in the figure below.
Commitment at national, state and district level are required to support and facilitate the implementation of Infection Prevention and Control (IPC) measures.
The important stakeholders in IPC include:
National Airborne Infection Control Committee (NAICC) has been constituted to provide for a multi-lateral national level coordinating body, to develop national guidelines on IPC, and provide technical guidance for their implementation, evaluation, and revisions.
Composition of NAICC
Respiratory hygiene is vital to prevent the spread of TB via aerosols and person-to-person transmission.
Respiratory hygiene includes:
Covering the nose/mouth with a tissue when coughing/sneezing and appropriate disposal of used tissues