In many settings, contact investigation may be an effective way to identify additional TB cases and stop the chain of transmission.

• Contact investigation should be conducted to find other patients who may have been infected or have active TB disease and need treatment.
• The names of all contacts in the household of sputum smear-positive PTB patients should be collected. (Some countries ask that smear-negative PTB and EPTB cases to also list household contacts.)
• A household contact is a person who lives in the home of a TB patient and who is therefore at greater risk of becoming infected and developing TB.