The essay focuses on the development of conspiracy narratives, with special attention to the evolution of mythologies in social networks. Stories of plots concerning health issues, and specifically of narratives about the Ebola virus, have carved out a significant space in the scenario of digital media. In 2014, in the regions of north–western Liberia, Sierra Leone, and Nigeria, thousands succumbed to the virus; according to the “Centers for Disease Control and Prevention”, it caused the most serious outbreak of hemorrhagic fever in history. As in the case of previous epidemics (AIDS, SARS, and so on), the massive spread of Ebola too was accounted for by numerous conspiracy theories. The essay analyzes processes and narratives that lie behind them, focusing on Facebook pages and Twitter accounts that boosted the diffusion of such mythologies.