Robinson Katy, Cohen Ted, Colijn Caroline
Bristol Centre for Complexity Sciences, Department of Engineering Mathematics, University of Bristol, Bristol, United Kingdom.
Theor Popul Biol. 2012 Mar;81(2):89-96. doi: 10.1016/j.tpb.2011.12.009. Epub 2012 Jan 8.
Sexually transmitted pathogens persist in populations despite the availability of biomedical interventions and knowledge of behavioural changes that would reduce individual-level risk. While behavioural risk factors are shared between many sexually transmitted infections, the prevalence of these diseases across different risk groups varies. Understanding this heterogeneity and identifying better control strategies depends on an improved understanding of the complex social contact networks over which pathogens spread. To date, most efforts to study the impact of sexual network structure on disease dynamics have focused on static networks. However, the interaction between the dynamics of partnership formation and dissolution and the dynamics of transmission plays a role, both in restricting the effective network accessible to the pathogen, and in modulating the transmission dynamics. We present a simple method to simulate dynamical networks of sexual partnerships. We inform the model using survey data on sexual attitudes and lifestyles, and investigate how the duration of infectiousness changes the effective contact network over which disease may spread. We then simulate several control strategies: screening, vaccination and behavioural interventions. Previous theory and research has advanced the importance of core groups for spread and control of STD. Our work is consistent with the importance of core groups, but extends this idea to consider how the duration of infectiousness associated with a particular pathogen interacts with host behaviours to define these high risk subpopulations. Characteristics of the parts of the network accessible to the pathogen, which represent the network structure of sexual contacts from the "point of view" of the pathogen, are substantially different from those of the network as a whole. The pathogen itself plays an important role in determining this effective network structure; specifically, we find that if the pathogen's duration of infectiousness is short, infection is more concentrated in high-activity, high-concurrency individuals even when all other factors are held constant. Widespread screening programmes would be enhanced by follow-up interventions targeting higher-risk individuals, because screening shortens the expected duration of infectiousness and causes a greater relative decrease in prevalence among lower-activity than in higher-activity individuals. Even for pathogens with longer durations of infectiousness, our findings suggest that targeting vaccination and behavioural interventions towards high-activity individuals provides comparable benefits to population-wide interventions.
尽管有生物医学干预措施，且人们也了解可降低个体层面风险的行为变化，但性传播病原体仍在人群中持续存在。虽然许多性传播感染存在共同的行为风险因素，但这些疾病在不同风险群体中的流行程度各不相同。了解这种异质性并确定更好的控制策略，取决于对病原体传播所涉及的复杂社会接触网络有更深入的理解。迄今为止，大多数研究性网络结构对疾病动态影响的工作都集中在静态网络上。然而，性伴侣形成和解散的动态过程与传播动态之间的相互作用，在限制病原体可接触的有效网络以及调节传播动态方面都发挥着作用。我们提出了一种模拟性伴侣动态网络的简单方法。我们利用关于性态度和生活方式的调查数据为模型提供信息，并研究传染性持续时间如何改变疾病可能传播的有效接触网络。然后，我们模拟了几种控制策略：筛查、疫苗接种和行为干预。先前的理论和研究已经强调了核心群体在性传播疾病传播和控制中的重要性。我们的工作与核心群体的重要性是一致的，但扩展了这一观点，以考虑与特定病原体相关的传染性持续时间如何与宿主行为相互作用来定义这些高风险亚群体。从病原体“视角”来看，病原体可接触的网络部分的特征，即性接触的网络结构，与整个网络的特征有很大不同。病原体本身在决定这种有效网络结构方面起着重要作用；具体而言，我们发现，如果病原体的传染性持续时间较短，即使所有其他因素保持不变，感染也更集中在高活跃度、高并发率的个体中。针对高风险个体的后续干预措施将加强广泛的筛查计划，因为筛查会缩短预期的传染性持续时间，并且与高活跃度个体相比，低活跃度个体中的患病率相对下降幅度更大。即使对于传染性持续时间较长的病原体，我们的研究结果表明，针对高活跃度个体进行疫苗接种和行为干预与全人群干预相比，能带来相当的益处。
