Throughout the history of epidemiology, visualizations have been used as the interface between public-health professionals and epidemiological data. The aim of this study was to examine the impact of the level of abstraction when using visualizations on routine infectious disease control. We developed three interactive visualization prototypes at increasing levels of abstraction to communicate subsets of influenza outbreak surveillance information. The visualizations were assessed through workshops in an exploratory evaluation with infectious disease epidemiologists. The results show that despite the potential of processed, abstract, and information-dense representations, increased levels of abstraction decreased epidemiologists' understanding and confidence in visualizations. Highly abstract representations were deemed not applicable in routine practice without training. Infectious disease epidemiologists' work routines and decision-making need to be further studied in order to develop visualizations that meet both the quality requirements imposed by policy-makers and the contextual nature of work practice.