Tracing the potential extra-household contacts of TB patients: findings from a personal social network survey in a high TB burden setting in India.

Abstract

Evidence on the extra-household contacts of TB patients who drive disease transmission is scarce. We conducted a cross-sectional personal social network survey among 300 newly diagnosed index pulmonary TB patients to identify their first-degree extra-household contacts. A significantly higher proportion of neighbourhood (3.5; 95% CI 1.3 to 7.5), occupational (3.2; 95% CI 1.3 to 9.2) and friendship contacts (2.2; 95% CI 0.8 to 4.5) developed TB within 1 y of the index patient's diagnosis than their household contacts (0.7; 95% CI 0.3 to 1.3). Similarly, a higher proportion of extra-household contacts had TB at different time points before the index patient was diagnosed. Extra-household contacts of TB patients could be a potential source of TB or could be at increased risk of TB.