Contact Tracing and Investigation

Index TB patient: Initially identified person of any age with new or recurrent TB in a specific household or other comparable settings in which others may have been exposed. The Index TB patient is the person on whom a contact investigation is centred, but is not necessarily the source/ primary case. 

Contact person: Any individual who was exposed to a person with active TB disease Household Contact (HHC) person: Person who shared the same enclosed living space as the index TB patient for one or more nights or for frequent or extended daytime periods during the three months before the start of current TB treatment. 

Close contact person: Person who is not in the household but shared an enclosed space, such as at a social gathering, workplace or facility, for extended periods during the day with the index TB patient during the three months before the commencement of the current TB treatment episode. 

Contact tracing: Contact tracing is the process of listing out all the contacts (household contact persons and close contact persons) of the index TB patient. Contact tracing has to be done for all Index TB cases, whether pulmonary (sputum positive or negative) or Extra-pulmonary (EPTB). As per the current policy, it is compulsory to trace household contact persons but it is desirable to trace other close contact persons (workplace, social gathering etc) also. 

Why Contact Tracing is done: Contact tracing is followed by contact investigation to identify active TB cases and Tuberculosis Preventive Treatment (TPT) beneficiaries. 

Contact investigation: This is a systematic process for identifying previously undiagnosed people with TB disease and TB infection, among the contact persons of an index TB patient. 

• Conducting Contact Tracing and Contact Investigation Once a new/ recurrent TB case is diagnosed (ideally within 1 week), a healthcare worker (usually the Multipurpose Worker (MPW) from the nearby public health facility visits/ tele calls the patient’s household, interviews the patient about their contact persons in the household and other settings such as workplace or social gatherings. 
• The contact persons’ details are recorded in a standardised format and entered in Ni-kshay contact tracing module. Each contact person's details enter the workflow as a presumptive TB case or TPT beneficiary. The traced contact persons are screened for TB using a symptom checklist and if found to have any symptoms suggestive of TB, they are tested using X-ray/ sputum microscopy/ Cartridge-based Nucleic Acid Amplification Test (CBNAAT) as required.
• Contact tracing is a process to identify people who are  at a high risk of developing TB due to their contact with a known TB case.

The aim of contact tracing is to find other people with TB disease and those infected with TB

• All close contact persons, especially household contact persons of a Pulmonary TB patient, should be screened for TB. 
• In paediatric TB patients, reverse contact tracing for the search of any active TB case in the child's household must be undertaken.
• Particular attention should be paid to contacts with the highest susceptibility to TB infection.

Figure: Contacts to be Prioritized for contact TB screening