Skip to main content
. Author manuscript; available in PMC: 2019 Jul 8.
Published in final edited form as: Soc Sci Med. 2018 Mar 30;206:117–122. doi: 10.1016/j.socscimed.2018.03.040

Fig. 2.

Fig. 2

A simplified typology of three ways to operationalize how co-occurring epidemics relate to each other. A, B, and C can be thought of either as diseases at the individual level or as epidemics at the population level. Panel 1 depicts mutually causal epidemics, described by Singer (1996): A and B are mutually causal, B and C are mutually causal, and A and C are mutually causal. Panel 2 depicts synergistically interacting epidemics, highlighted in Singer and Clair (2003): A and B both cause C, and their total effect on C exceeds the sum of their individual effects alone. Panel 3 depicts serially causal epidemics: A causes B, which then causes C. This model is related to theories of accumulating health risks.