IEC-CH3: Diagnostic Technologies

Screening for active tuberculosis (TB) a process to filter out people who are less likely to have TB, from a group. Screened positive people are likely to have TB and are confirmed subsequently using a TB diagnostic test. This will allow finite diagnostic testing resources to be used on the remaining.

Screening in TB may be performed ​using simple field tools (4 Symptom complex) and tests such as Chest X-ray, or a combination of both. ​Combination of both is the most effective, but is often not applied due to the practical difficulties in making a chest X-ray conveniently available.

Screening is an integral part of any general case finding effort. It is also applied systematically in specific situations.

1. At health care facilities (intensified case finding): Here those visiting are screened using the 4 symptom complex, often at the point of entry to the facility. Those screened positive may be fast-tracked to TB Diagnostic testing.
2. In vulnerable populations in active case finding efforts: Here the entire population identified for active case finding are screened using the pre-decided protocols by going door to door. 

Resources

• Systematic Screening for Active Tuberculosis; Principles and Recommendations, WHO 2013.
• National Strategic Plan for Tuberculosis Elimination 2020–2025.

People who have been exposed to patients with infectious TB are known as TB contacts; they constitute a high-risk group for TB. Case finding investigation contributes to the early detection of TB cases, and results in identifying a significant number of additional patients.

Figure: Approaches to Tuberculosis Case Finding

Active case-finding requires systematic screening and clinical evaluation of populations who are at high risk of developing TB, such as people living in slums, tribal areas, congregate settings, persons who are household contacts of TB cases

Resources:

• Assessing TB Case-Finding

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Systematic screening of all individuals of a defined population is known as active case finding.  It is applied outside of health facilities at the community level by the health system.

Objective of ACF is to:

1. identify cases early, initiate prompt treatment, reduce risk of poor treatment outcomes and reduce risk of further transmission of TB
2. to provide access to diagnosis services to populations that would have been otherwise unreached

It is effort intensive and is recommended only in population groups where there is estimated high case load. In NTEP, ACF is recommended only to be performed in Key / vulnerable population.

ACF can also be clubbed with suitable ACSM campaigns to create awareness about the signs and symptoms and about TB in the target population/ community. It can also be combined with other health activities/ campaigns (such as Pulse Polio/ Leprosy screening/ population based screening for NCDs) for increased efficiency.

Resources

1. Training Modules for Programme Managers and Medical Officers.
2. Active TB Case Finding, Guidance Document.
3. WHO recommendations for Systematic Screening for Active Tuberculosis

Assessment

Resources:

• Guidelines for Programmatic Management of Drug Resistant Tuberculosis in India, March 2021 
• WHO Consolidated Guidelines on Tuberculosis: Module 4-Treatment: Drug resistant TB Treatment, 2020