Global Health Institute, College of Public Health, University of Georgia, Athens, Georgia, USA.
Department of Epidemiology and Biostatistics, College of Public Health, University of Georgia, Athens, Georgia, USA.
Clin Infect Dis. 2021 Nov 2;73(9):e3438-e3445. doi: 10.1093/cid/ciaa1556.
Although households of tuberculosis (TB) cases represent a setting for intense transmission of Mycobacterium tuberculosis, household exposure accounts for <20% of transmission within a community. The aim of this study was to estimate excess risk of M. tuberculosis infection among household and extra-household contacts of index cases.
We performed a cross-sectional study in Kampala, Uganda, to delineate social networks of TB cases and matched controls without TB. We estimated the age-stratified prevalence difference of TB infection between case and control networks, partitioned as household and extra-household contacts.
We enrolled 123 index cases, 124 index controls, and 2415 first-degree network contacts. The prevalence of infection was highest among household contacts of cases (61.5%), lowest among household contacts of controls (25.2%), and intermediary among extra-household TB contacts (44.9%) and extra-household control contacts (41.2%). The age-adjusted prevalence difference between extra-household contacts of cases and their controls was 5.4%. The prevalence of infection was similar among the majority of extra-household case contacts and corresponding controls (47%).
Most first-degree social network members of TB cases do not have adequate contact with the index case to experience additional risk for infection, but appear instead to acquire infection through unrecognized exposures with infectious cases in the community.
尽管结核病例的家庭构成了结核分枝杆菌高度传播的环境，但家庭接触仅占社区内传播的<20%。本研究旨在估计病例的家庭和家庭外接触者中结核分枝杆菌感染的超额风险。
我们在乌干达坎帕拉进行了一项横断面研究，以描绘结核病例和无结核对照的社会网络。我们估计了病例和对照网络之间结核感染的年龄分层患病率差异，并将其划分为家庭和家庭外接触者。
我们招募了 123 例索引病例、124 例对照和 2415 名一级网络接触者。家庭接触者的感染率最高（61.5%），对照的家庭接触者的感染率最低（25.2%），家庭外结核接触者和家庭外对照接触者的感染率居中（44.9%和 41.2%）。病例的家庭外接触者与对照之间的年龄调整后患病率差异为 5.4%。大多数病例的家庭外接触者与相应的对照者（47%）的感染率相似。
结核病例的大多数一级社会网络成员与该病例的接触并不足以增加感染的风险，但似乎是通过社区中未被识别的具有传染性的病例暴露而感染。
