Following are the risk factors that increase the chances of developing TB disease in an individual:

Figure: Risk factors for developing active TB

Resources:

Specificity is the test’s ability to correctly designate a subject without the disease as negative.

Specificity of a test is the percentage of true negatives out of all subjects who do not have a disease or condition.

Simply, specificity is the proportion of people without disease correctly diagnosed as negative by a test. In other words, it is the ability of the test or instrument to obtain normal range or negative results for a person who does not have a disease. 

The formula to determine specificity is the following:

Sensitivity is the proportion of true positive tests out of all patients with a condition.

In other words, it is the ability of a test or instrument to yield a positive result for a subject that has that disease. A test that is 100% sensitive means all sick individuals are correctly identified as sick, i.e., there are no false negatives. Importantly, as the calculation involves all patients with the disease, it is not affected by the prevalence of the disease.

Define and explain the concept of Specificity of a TB test and its calculation.

Define the concept of sensitivity of a TB test and explain its calculation. 

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.

Describe TB notification and describe the TB Notification Rate and its calculation.

Describe and define the prevalence rate for TB disease and its calculation.