A contact person in the context of an environmental investigation for tuberculosis is any person who has had close contact with a person suffering from tuberculosis. It is particularly important how and for how long the contact lasted. Contact persons usually include family members, friends, work colleagues or classmates. Contact persons can also be strangers with whom the infected person was in a closed room for a longer period of time.

As a rule, all contacts and places of residence in the last 6 months are taken into account in the environmental examination. The public health department explains to those affected exactly which contacts must be specified. The public health department then decides which contacts actually need to be tested.