Understanding host interactions that lead to pathogen transmission is fundamental to the prediction and control of epidemics1–5. Although the majority of transmissions often occurs within social groups6–9, the contribution of connections that bridge groups and species to pathogen dynamics is poorly understood10–12. 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 populations13–15. 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.Cryptic connections facilitate the community-wide spread of disease both within and among species.

中文翻译：

---

隐秘的联系阐明了社区网络内的病原体传播

了解导致病原体传播的宿主相互作用是预测和控制流行病的基础1-5。尽管大多数传播通常发生在社会群体内 6-9，但人们对连接群体和物种的联系对病原体动态的贡献知之甚少10-12。这些隐秘的联系——通常是间接的或不频繁的——提供了原本断开连接的个体之间的传播途径，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，我们通过同时表征社交网络并通过八个蝙蝠社区追踪替代病原体流行病的传播动态，量化了疾病动态中神秘联系的重要性。然后，我们将这些数据与引起白鼻综合征的真菌病原体的入侵进行了比较，这是一种最近出现的疾病，正在破坏北美蝙蝠种群 13-15。我们发现，神秘的联系将个体之间和物种之间的联系增加了一个数量级。平均而言，个人通过直接接触与不到 2% 的人口有联系，而通过共享群体仅与 6% 的人口有联系。然而，追踪替代病原体动态表明每个个体都与近 15% 的种群有关，并揭示了单独栖息个体之间的广泛传播以及物种之间的广泛接触。从替代病原体流行病估计的联系，包括神秘的联系，解释了导致白鼻综合征的真菌传播的变异是基于共享群体的连接的三倍。这些发现表明，隐性联系如何促进病原体在社区范围内的传播，并可能导致爆发性流行病。隐性联系促进了疾病在物种内部和物种之间的社区范围传播。