Statistics, Modelling and Economics Department, 61 Colindale Avenue, Colindale, London, NW9 5HT, UK.
TB Modelling Group, Centre for Mathematical Modelling of Infectious Diseases, TB Centre and Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.
BMC Infect Dis. 2019 Jan 7;19(1):26. doi: 10.1186/s12879-018-3585-8.
Transmission patterns in high tuberculosis incidence areas in England are poorly understood but need elucidating to focus contact tracing. We study transmission within and between age, ethnic and immigrant groups using molecular data from the high incidence West Midlands region.
Isolates from culture-confirmed tuberculosis cases during 2007-2011 were typed using 24-locus Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeats (MIRU-VNTR). We estimated the proportion of disease attributable to recent transmission, calculated the proportion of isolates matching those from the two preceding years ("retrospectively clustered"), and identified risk factors for retrospective clustering using multivariate analyses. We calculated the ratio (RCR) between the observed and expected proportion clustered retrospectively within or between age, ethnic and immigrant groups.
Of the 2159 available genotypes (79% of culture-confirmed cases), 34% were attributed to recent transmission. The percentage retrospectively clustered decreased from 50 to 24% for 0-14 and ≥ 65 year olds respectively (p = 0.01) and was significantly lower for immigrants than the UK-born. Higher than expected clustering occurred within 15-24 year olds (RCR: 1.4 (95% CI: 1.1-1.8)), several ethnic groups, and between UK-born or long-term immigrants with the UK-born (RCR: 1.8 (95% CI: 1.1-2.4) and 1.6 (95% CI: 1.2-1.9) respectively).
This study is the first to consider "who clusters with whom" in a high incidence area in England, laying the foundation for future whole-genome sequencing work. The higher than expected clustering seen here suggests that preferential mixing between some age, ethnic and immigrant groups occurs; prioritising contact tracing to groups with which cases are most likely to cluster retrospectively could improve TB control.
在英国结核病高发地区，传播模式了解甚少，但需要加以阐明，以便集中进行接触者追踪。我们使用来自高发病率西米德兰兹地区的分子数据，研究年龄、族裔和移民群体内部和群体之间的传播。
使用 24 个基因座分枝杆菌散布重复单位-可变数目串联重复（MIRU-VNTR）对 2007-2011 年培养确诊的结核病病例分离株进行分型。我们估计了疾病归因于近期传播的比例，计算了与前两年分离株相匹配的分离株的比例（回顾性聚类），并使用多变量分析确定了回顾性聚类的危险因素。我们计算了观察到的和预期的在年龄、族裔和移民群体内部或之间进行回顾性聚类的比例之间的比值（RCR）。
在 2159 个可获得的基因型（79%的培养确诊病例）中，有 34%归因于近期传播。0-14 岁和≥65 岁人群的回顾性聚类百分比分别从 50%降至 24%（p=0.01），移民的聚类比例明显低于英国出生者。15-24 岁人群的聚类比例高于预期（RCR：1.4（95%CI：1.1-1.8）），一些族裔群体以及英国出生者或长期移民之间的聚类比例也高于预期（RCR：1.8（95%CI：1.1-2.4）和 1.6（95%CI：1.2-1.9））。
这项研究首次在英国高发病率地区考虑了“谁与谁聚类”，为未来的全基因组测序工作奠定了基础。这里观察到的高于预期的聚类表明，一些年龄、族裔和移民群体之间存在优先混合；优先对与病例最有可能进行回顾性聚类的群体进行接触者追踪，可能会改善结核病控制。
