Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA, USA.
Department of Biological Sciences, Virginia Polytechnic Institute, Blacksburg, VA, USA.
Nature. 2018 Nov;563(7733):710-713. doi: 10.1038/s41586-018-0720-z. Epub 2018 Nov 19.
Understanding host interactions that lead to pathogen transmission is fundamental to the prediction and control of epidemics. Although the majority of transmissions often occurs within social groups, the contribution of connections that bridge groups and species to pathogen dynamics is poorly understood. These cryptic connections-which are often indirect or infrequent-provide transmission routes between otherwise disconnected individuals and may have a key role in large-scale outbreaks that span multiple populations or species. Here we quantify the importance of cryptic connections in disease dynamics by simultaneously characterizing social networks and tracing transmission dynamics of surrogate-pathogen epidemics through eight communities of bats. We then compared these data to the invasion of the fungal pathogen that causes white-nose syndrome, a recently emerged disease that is devastating North American bat populations. We found that cryptic connections increased links between individuals and between species by an order of magnitude. Individuals were connected, on average, to less than two per cent of the population through direct contact and to only six per cent through shared groups. However, tracing surrogate-pathogen dynamics showed that each individual was connected to nearly fifteen per cent of the population, and revealed widespread transmission between solitarily roosting individuals as well as extensive contacts among species. Connections estimated from surrogate-pathogen epidemics, which include cryptic connections, explained three times as much variation in the transmission of the fungus that causes white-nose syndrome as did connections based on shared groups. These findings show how cryptic connections facilitate the community-wide spread of pathogens and can lead to explosive epidemics.
理解导致病原体传播的宿主相互作用对于预测和控制传染病至关重要。尽管大多数传播通常发生在社会群体内部，但连接群体和物种的桥梁对病原体动态的贡献却知之甚少。这些隐蔽的连接——通常是间接的或不频繁的——为原本不相连的个体之间提供了传播途径，并且可能在跨越多个种群或物种的大规模爆发中发挥关键作用。在这里，我们通过同时描述蝙蝠的八个群体的社交网络并追踪替代病原体的传播动态，来量化隐蔽连接在疾病动态中的重要性。然后，我们将这些数据与真菌病原体白鼻综合征的入侵进行了比较，白鼻综合征是一种最近出现的疾病，正在摧毁北美的蝙蝠种群。我们发现，隐蔽连接将个体之间和物种之间的联系增加了一个数量级。通过直接接触，个体平均与不到总人口的 2%的个体相连，而通过共享群体，个体平均与总人口的 6%相连。然而，追踪替代病原体的动态表明，每个个体与近 15%的种群相连，并揭示了独居蝙蝠之间的广泛传播以及物种之间的广泛接触。从包括隐蔽连接的替代病原体流行病中估计的连接，比基于共享群体的连接解释白鼻综合征病原体传播的变异多三倍。这些发现表明了隐蔽连接如何促进病原体在整个社区的传播，并可能导致爆发性的流行病。
