Population Health Sciences, Bristol Medical School, University of Bristol, Bristol, United Kingdom.
Bristol Veterinary School, University of Bristol, Bristol, United Kingdom.
PLoS Comput Biol. 2020 Mar 27;16(3):e1007687. doi: 10.1371/journal.pcbi.1007687. eCollection 2020 Mar.
Tuberculosis (TB) remains a public health threat in low TB incidence countries, through a combination of reactivated disease and onward transmission. Using surveillance data from the United Kingdom (UK) and the Netherlands (NL), we demonstrate a simple and predictable relationship between the probability of observing a cluster and its size (the number of cases with a single genotype). We demonstrate that the full range of observed cluster sizes can be described using a modified branching process model with the individual reproduction number following a Poisson lognormal distribution. We estimate that, on average, between 2010 and 2015, a TB case generated 0.41 (95% CrI 0.30,0.60) secondary cases in the UK, and 0.24 (0.14,0.48) secondary cases in the NL. A majority of cases did not generate any secondary cases. Recent transmission accounted for 39% (26%,60%) of UK cases and 23%(13%,37%) of NL cases. We predict that reducing UK transmission rates to those observed in the NL would result in 538(266,818) fewer cases annually in the UK. In conclusion, while TB in low incidence countries is strongly associated with reactivated infections, we demonstrate that recent transmission remains sufficient to warrant policies aimed at limiting local TB spread.
结核病（TB）仍然是低发病率国家的公共卫生威胁，这是由于再激活疾病和继续传播的综合作用。我们使用来自英国（UK）和荷兰（NL）的监测数据，展示了观察到的集群的概率与其大小（具有单一基因型的病例数量）之间的简单而可预测的关系。我们证明，使用带有个体繁殖数遵循泊松对数正态分布的修改分支过程模型，可以描述观察到的集群大小的全部范围。我们估计，在 2010 年至 2015 年期间，英国的一个结核病病例平均产生 0.41（95%CrI 0.30，0.60）例继发性病例，而 NL 则产生 0.24（0.14，0.48）例继发性病例。大多数病例没有产生任何继发性病例。近期传播占英国病例的 39%（26%，60%），NL 病例的 23%（13%，37%）。我们预测，将英国的传播率降低到 NL 观察到的水平，将使英国每年的病例减少 538（266，818）例。总之，虽然低发病率国家的结核病与再激活感染密切相关，但我们证明，近期传播仍然足以证明采取政策限制当地结核病传播是合理的。
