Long-term dynamics of measles in London: Titrating the impact of wars, the 1918 pandemic, and vaccination
Long-term dynamics of measles in London: Titrating the impact of wars, the 1918 pandemic, and vaccination
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DOI：
10.1371/journal.pcbi.1007305
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发表时间：
2019-09-01
影响因子：
4.3
通讯作者：
Grenfell, Bryan T.
中科院分区：
文献类型：
--
作者：
Becker, Alexander D.;Wesolowski, Amy;Grenfell, Bryan T.
生态学中的一个关键问题是内部非线性动力学和外部扰动对自然系统长期轨迹的相对影响。由于宿主-病原体生命周期的振荡性质、丰富的数据来检验理论和公共卫生相关性，麻疹已被广泛分析为消费者-资源动态的范例。特别是伦敦的麻疹动态，已经成为使用疫苗接种前时代（1944-1967年）的发病率数据进行此类分析的原型测试床。然而，在此期间，外部大规模扰动很少，限制了对内部和外部人口扰动对东道国人口的相对影响的评估。在这里，我们扩展了以前的伦敦分析，包括近世纪的数据，这些数据也包含四个主要的人口变化：第一次和第二次世界大战，1918年流感大流行，以及麻疹大规模疫苗接种计划的开始。通过使用粒子滤波方法结合死亡率和发病率数据，我们证明了一个简单的随机流行病模型，具有最小的历史规格，可以捕获近100年的动态，包括由每个主要扰动引起的变化。我们发现，大多数的动态变化是可以解释的内部非线性动态系统，调整人口变化。此外，1918年的流感大流行和第二次世界大战对这一基本的流行病振荡器起到了额外的扰动作用。我们的分析强调，长期的生态和流行病学动态可以遵循非常简单的规则，即使在一个非静止的人口受到重大扰动和重大的长期变化。
A key question in ecology is the relative impact of internal nonlinear dynamics and external perturbations on the long-term trajectories of natural systems. Measles has been analyzed extensively as a paradigm for consumer-resource dynamics due to the oscillatory nature of the host-pathogen life cycle, the abundance of rich data to test theory, and public health relevance. The dynamics of measles in London, in particular, has acted as a prototypical test bed for such analysis using incidence data from the pre-vaccination era (1944-1967). However, during this timeframe there were few external large-scale perturbations, limiting an assessment of the relative impact of internal and extra demographic perturbations to the host population. Here, we extended the previous London analyses to include nearly a century of data that also contains four major demographic changes: the First and Second World Wars, the 1918 influenza pandemic, and the start of a measles mass vaccination program. By combining mortality and incidence data using particle filtering methods, we show that a simple stochastic epidemic model, with minimal historical specifications, can capture the nearly 100 years of dynamics including changes caused by each of the major perturbations. We show that the majority of dynamic changes are explainable by the internal nonlinear dynamics of the system, tuned by demographic changes. In addition, the 1918 influenza pandemic and World War II acted as extra perturbations to this basic epidemic oscillator. Our analysis underlines that long-term ecological and epidemiological dynamics can follow very simple rules, even in a non-stationary population subject to significant perturbations and major secular changes.