When does a supershedder become a superspreader?: The impact of individual-level heterogeneities on population-level transmission and spread

超级传播者何时成为超级传播者？：个体水平异质性对群体水平传播和传播的影响

• 批准号: NE/X01424X/1
• 负责人: Amy Pedersen
• 金额: $ 103.47万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX01424X%2F1
• 关键词: When; does; supershedder; become; superspreader

Individuals vary greatly in both their susceptibility to infection and their likelihood of transmitting infections to others. Evidence from various disease outbreaks suggests that typically a minority of individuals (~20%) cause the majority of new cases (~80%) - these are the so-called "superspreaders". However, it is not clear what characteristics make someone a superspreader. As we are only too aware from the COVID-19 pandemic, an individual's infection risk depends on how close and for how long they spend near infected individuals, such that some infected individuals may contact a disproportionately high number of susceptible individuals, acting as 'supercontactors'. Hence, supercontactors may indeed be superspreaders and drive transmission for many infectious diseases. However, it is also possible that some individuals release many more infectious stages than others, acting as 'supershedders', which can also lead to disproportionately greater transmission potential. To complicate matters, these two processes, supershedding and supercontacting, can interact together - either exacerbating transmission (generally, if supershedders also tend to be supercontactors) or diminishing transmission (if supershedders tend to have few contacts, and vice versa). These processes, whether driven by individuals having large numbers of contacts or being highly infectious, then scale up to determine how fast the parasite spreads through the host population, and the spatial distribution of infection 'hotspots'. As such, understanding the individual characteristics that determine supershedders and supercontactors, and how they are coupled to give rise to superspreaders, are crucial to predicting disease spread and for devising effective control measures.So far, research on what host characteristics make a superspreader has focussed almost exclusively on pathogenic viral or bacterial outbreaks in humans. While clearly essential from a public health perspective, this narrow focus on certain human pathogens limits our ability to explicitly test the mechanisms underlying superspreading. Furthermore, it is far from clear how ideas of supercontacting and supershedding apply to the vast range of parasites with very different transmission modes and biologies from the pathogens that cause epidemics (or pandemics) in humans. In particular, parasitic worms (helminths) are a ubiquitous and integral component of all natural ecosystems, playing a vital role in structuring ecological communities and having significant health and economic consequences for wildlife, humans and domestic animals. These helminths typically infect new hosts through long-lived infective stages that reside in the environment, thereby blurring the definition of 'contacts', and making it virtually impossible to determine the number of new infections arising from each initially infected individual. Hence, established concepts relating supershedding, supercontacting, and superspreading do not apply directly to this important groups of parasites.Here we will move this field forward through a comprehensive study that uses novel population-level field experiments in a highly tractable yet natural host-parasite system, wood mice and their parasitic worms, in which we can specifically reduce infections in either supershedding or supercontacting individuals. We will pair these field experiments with new theory and robust analytical methods to develop an in-depth understanding of how between-individual variation in infectiousness, movement patterns, and parasite transmission mode interact to drive parasite spread in natural communities.

个体在感染的敏感性和向他人传播感染的可能性方面都有很大差异。来自各种疾病暴发的证据表明，通常有少数人（约20％）导致大多数新病例（〜80％） - 这些是所谓的“超级公民”。但是，尚不清楚哪种特征使某人成为超级公民。由于我们只从199大流行中得知，因此个人的感染风险取决于他们在感染的个体附近花费多长时间，以至于某些受感染的人可能会与不成比例的易感人群接触，并作为“超级接触器”。因此，超级接触剂确实可能是超级传播者，并且可以为许多传染病而传播传播。但是，有些人也有可能发行比其他人更具传染性阶段，而这些阶段也可能是“ Supershedders”，这也可能导致不成比例的传播潜力。使事情复杂化，这两个过程（超级示射和超接触）可以一起相互作用 - 加剧传播（通常，如果超级示威者也倾向于是超级接触器），则可以减少传播（如果SuperShedders往往往往具有很少的接触，反之亦然）。这些过程，无论是由具有大量接触的个体驱动还是高度感染力，然后扩展以确定寄生虫通过宿主人群传播的速度，以及感染“热点”的空间分布。因此，了解确定Supershedder和超级接触器的个体特征，以及如何耦合以产生超级传播者，这对于预测疾病的传播和设计有效的控制措施至关重要。如此迄今为止，研究宿主的特征使超级专家几乎专注于致病的病毒性病毒或细菌爆发。从公共卫生的角度来看，显然至关重要，但这种对某些人类病原体的关注狭窄，限制了我们明确测试超级扩展机制的能力。此外，很清楚，超级接触和超级传播的思想如何适用于与引起人类流行病（或大流行性）的病原体非常不同的传播模式和生物学不同的寄生虫。特别是，寄生虫（蠕虫）是所有自然生态系统中无处不在的组成部分，在构建生态社区以及对野生动植物，人类和家畜的重大健康和经济后果方面发挥了至关重要的作用。这些蠕虫通常通过存在于环境中的长寿命感染阶段感染新宿主，从而模糊了“接触”的定义，并且几乎不可能确定每个最初受感染的个体引起的新感染数量。因此，与超级接触，超级接触和超级主张相关的既定概念并不直接适用于这一重要的寄生虫组。在这里，我们将通过一项全面的研究来向前迈进，该研究使用一项新颖的人口层面实验实验，在高度可触犯的宿主宿主系统中，木材小鼠及其帕斯西氏虫蠕虫中，我们可以在特定的范围内进行精神，或者在特定的范围内降低了Intections。我们将将这些现场实验与新理论和可靠的分析方法相结合，以深入了解传染性，运动模式和寄生虫传播模式如何相互作用以驱动寄生虫在自然社区中传播。