The Lancet
Mar 04, 2017 Volume 389 Number 10072 p881-982 e3
http://www.thelancet.com/journals/lancet/issue/current

Viewpoint
Co-occurring epidemics, syndemics, and population health
Alexander C Tsai, Emily Mendenhall, James A Trostle, Ichiro Kawachi
Summary
As originally theorised, three concepts underlie the notion of a syndemic: disease concentration, disease interaction, and the large-scale social forces that give rise to them.1,2 The concept of disease concentration holds that two or more epidemics co-occur in particular temporal or geographical contexts due to harmful social conditions. This aspect of the theory of syndemics is not necessarily what makes its contribution distinctive. For example, anthropologists have long called attention to the manner in which large-scale political, economic, and cultural forces have given rise to clustered epidemics of various infectious diseases, most prominently HIV and tuberculosis;3–5 and the theory of fundamental causes highlights the roles of these forces in driving concentrated health disadvantage.