Department of Epidemiology, Harvard School of Public Health, Brigham and Women's Hospital, Massachusetts General Hospital, Boston, USA.
J Infect Dis. 2011 Jun 1;203(11):1582-9. doi: 10.1093/infdis/jir162.
Tuberculosis (TB) often occurs among household contacts of people with active TB. It is unclear whether clustering of cases represents household transmission or shared household risk factors for TB.
We used cross-sectional data from 764 households in Lima, Peru, to estimate the relative contributions of household and community transmission, the average time between cases, and the immunity afforded by a previous TB infection.
The distribution of cases per household suggests that almost 7 of 10 nonindex household cases were infected in the community rather than in the household. The average interval between household cases was 3.5 years. We observed a saturation effect in the number of cases per household and estimated that protective immunity conferred up to 35% reduction in the risk of disease.
Cross-sectional household data can elucidate the natural history and transmission dynamics of TB. In this high-incidence setting, we found that the majority of cases were attributable to community transmission and that household contacts of case patients derive some immunity from household exposures. Screening of household contacts may be an effective method of detecting new TB cases if carried out over several years.
结核病（TB）经常发生在活动性结核病患者的家庭接触者中。目前尚不清楚病例的聚集是否代表家庭传播或结核病的共同家庭危险因素。
我们使用来自秘鲁利马的 764 户家庭的横断面数据来估计家庭和社区传播、病例之间的平均时间以及既往结核感染提供的免疫力的相对贡献。
每个家庭的病例分布表明，近 10 个非索引家庭病例中有近 7 个是在社区而不是在家庭中感染的。家庭病例之间的平均间隔为 3.5 年。我们观察到家庭病例数量的饱和效应，并估计保护性免疫可将疾病风险降低 35%。
横断面家庭数据可以阐明结核病的自然史和传播动态。在这种高发环境中，我们发现大多数病例归因于社区传播，并且病例患者的家庭接触者从家庭接触中获得了一定的免疫力。如果在几年内进行多次筛查，对家庭接触者进行筛查可能是发现新结核病例的有效方法。
