This paper analyzes ethnographic and cartographic evidence from Sierra Leone that show the limitations of big data relative to the containment of Ebola. In this paper, big data is both a technology itself and also a foundation and catalyst for other technologies. Early in 2014, big data’s technologies of data collection as well as its algorithmic functions were heralded by US media for detecting the West African Ebola outbreak. Later in the epidemic, big data - specifically, data from millions of cell phones - was further hyped as able to help stop the infectious and often fatal disease by tracking the mobility and migrations of contagious people. Big data’s failures in this case are directly linked to what big data epidemiologists did not understand about the social life and thing-self issues of cell phones in Sierra Leone. In addition to identifying ethical concerns about human contagion tracking, the paper shows that cell phones did not serve well as beacons of contagion because they do not operate as inalienable indicators of individual property and identity in Sierra Leone.