Tuberculosis contact investigation in a high-burden setting: house or household?

SETTING: A high tuberculosis (TB) burden setting, South Africa. Two frequently used definitions for 'household' are 1) 'all dwellings on the same plot of land that share the same residential address'; and 2) 'a group of persons who live together in the same dwelling unit and who have the same eating arrangements'.
OBJECTIVE: To characterise a household and the outcome of investigations in household child contacts using definition 1 compared to definition 2 during a TB contact investigation.
DESIGN: Access to a household (definition 1) was gained via an adult TB case. Children were assessed for TB infection and disease.
RESULTS: Household enumeration indicated 25 members of three families living in a main house and a fourth family living in an adjacent structure. Three children were diagnosed with TB and two referred for isoniazid preventive therapy. Families living in the main house shared the main kitchen, while the yard house family used its own kitchen. This household would have been classified as two separate households if definition 2 had been used, and children with TB disease and infection would have been missed.
CONCLUSION: The definition of household in TB contact investigation should provide a framework that is broad enough to capture the majority of children at risk.