Department of Community Medicine and School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong SAR, China.
PLoS One. 2010 May 3;5(5):e10468. doi: 10.1371/journal.pone.0010468.
Hong Kong is an affluent subtropical city with a well-developed healthcare infrastructure but an intermediate TB burden. Declines in notification rates through the 1960s and 1970s have slowed since the 1980s to the current level of around 82 cases per 100 000 population. We studied the transmission dynamics of TB in Hong Kong to explore the factors underlying recent trends in incidence.
METHODOLOGY/PRINCIPAL FINDINGS: We fitted an age-structured compartmental model to TB notifications in Hong Kong between 1968 and 2008. We used the model to quantify the proportion of annual cases due to recent transmission versus endogenous reactivation of latent infection, and to project trends in incidence rates to 2018. The proportion of annual TB notifications attributed to endogenous reactivation increased from 46% to 70% between 1968 and 2008. Age-standardized notification rates were projected to decline to approximately 56 per 100 000 in 2018.
CONCLUSIONS/SIGNIFICANCE: Continued intermediate incidence of TB in Hong Kong is driven primarily by endogenous reactivation of latent infections. Public health interventions which focus on reducing transmission may not lead to substantial reductions in disease burden associated with endogenous reactivation of latent infections in the short- to medium-term. While reductions in transmission with socio-economic development and public health interventions will lead to declines in TB incidence in these regions, a high prevalence of latent infections may hinder substantial declines in burden in the longer term. These findings may therefore have important implications for the burden of TB in developing regions with higher levels of transmission currently.
香港是一个富裕的亚热带城市，拥有发达的医疗保健基础设施，但结核病负担处于中等水平。自 20 世纪 80 年代以来，通报率的下降速度已经放缓，目前约为每 10 万人 82 例。我们研究了香港结核病的传播动态，以探讨发病率近期趋势的背后因素。
方法/主要发现：我们将年龄结构的 compartmental 模型应用于 1968 年至 2008 年香港的结核病通报中。我们使用该模型来量化每年新发病例中归因于近期传播和潜伏感染内源性再激活的比例，并预测发病率趋势至 2018 年。在 1968 年至 2008 年期间，归因于内源性再激活的年度结核病通报比例从 46%增加到 70%。预计标准化发病率将在 2018 年下降到约 56 例/10 万人。
结论/意义：香港结核病的持续中等发病率主要是由潜伏感染的内源性再激活驱动的。以减少传播为重点的公共卫生干预措施可能不会在短至中期内导致与潜伏感染内源性再激活相关的疾病负担的显著减少。随着社会经济发展和公共卫生干预措施的减少，这些地区的结核病发病率将会下降，但潜伏感染的高患病率可能会在长期内阻碍负担的大幅下降。这些发现可能对目前传播水平较高的发展中地区的结核病负担具有重要意义。
