Yeo Ivan K T, Tannenbaum Terry, Scott Allison N, Kozak Robert, Behr Marcel A, Thibert Louise, Schwartzman Kevin
Respiratory Epidemiology Unit, McGill University, Montreal, Quebec, Canada.
Pediatr Infect Dis J. 2006 Nov;25(11):1037-43. doi: 10.1097/01.inf.0000241101.12510.3c.
Tuberculosis (TB) in young children is an indicator of ongoing community transmission. We examined contact investigations related to pediatric TB, yield for source case identifications and genotypes for relevant Mycobacterium tuberculosis isolates in a low-incidence setting.
We reviewed public health data for all patients with TB aged <18 years reported to Montreal authorities during 1996 to 2000. M. tuberculosis isolates from patients of all ages were subjected to IS6110-based genotyping, supplemented by spoligotyping, to compare isolates from children and adults during the same years.
Sixty-six patients aged <18 years were diagnosed with active TB from 1996 to 2000. Mean age was 11.1 years (standard deviation 6.7 years). Twenty-five children (38%) were Canadian-born, all with at least one foreign-born parent. Nineteen children were diagnosed after contact investigations of known adult cases; 8 underwent no contact investigation. For the remaining 39 children, a total of 616 contacts were identified. The median number of contacts per child was 9 (interquartile range, 6-10). Four hundred eighty-one contacts (78%) underwent tuberculin testing; 188 (39%) were reactors and 186 (39%) began treatment of latent TB. Investigations uncovered 4 probable source cases, all involving parents or other relatives. M. tuberculosis genotyping for 38 children identified up to 14 additional possible source cases; in only one was a possible epidemiologic link evident from public health records.
Among largely foreign-born children with active TB, contact investigations were extensive and often identified latent tuberculosis infection--but rarely source cases. However, genotyping suggested substantial, previously unrecognized transmission to children despite low overall incidence.
幼儿结核病是社区持续传播的一个指标。我们在一个低发病率地区研究了与儿童结核病相关的接触者调查、传染源识别率以及相关结核分枝杆菌分离株的基因型。
我们回顾了1996年至2000年期间向蒙特利尔当局报告的所有18岁以下结核病患者的公共卫生数据。对所有年龄段患者的结核分枝杆菌分离株进行基于IS6110的基因分型，并辅以间隔寡核苷酸分型，以比较同一年儿童和成人的分离株。
1996年至2000年期间，66名18岁以下患者被诊断为活动性结核病。平均年龄为11.1岁（标准差6.7岁）。25名儿童（38%）在加拿大出生，其父母至少有一方是外国出生。19名儿童在对已知成人病例进行接触者调查后被诊断；8名儿童未接受接触者调查。对于其余39名儿童，共识别出616名接触者。每名儿童接触者的中位数为9名（四分位间距，6 - 10）。481名接触者（78%）接受了结核菌素检测；188名（39%）检测呈阳性，186名（39%）开始接受潜伏性结核治疗。调查发现了4名可能的传染源，均涉及父母或其他亲属。对38名儿童的结核分枝杆菌基因分型确定了另外14名可能的传染源；从公共卫生记录中仅明显看出其中1名存在可能的流行病学关联。
在主要为外国出生的活动性结核病儿童中，接触者调查范围广泛，且常常能识别出潜伏性结核感染，但很少能找到传染源。然而基因分型表明，尽管总体发病率较低，但存在大量此前未被认识到的儿童传播情况。
