Gang Violence Spreads Like An Infectious Disease

April M. Zeoli, PhD, MPH Associate Professor School of Criminal Justice Michigan State Interview with:
April M. Zeoli, PhD, MPH
Associate Professor
School of Criminal Justice
Michigan State University
Lansing, MI 48824

Medical Research: What is the background for this study? What are the main findings?

Dr. Zeoli: My team and I are interested in whether an infectious disease model can be applied to homicide. In other words, can homicide be described as being “contagious” and does it spread through a city in a systematic pattern? In our previous research, we showed that homicide did spread through Newark, New Jersey, in a manner similar to an infectious disease ( However, not all types of homicide may be “contagious.” In this research, we looked at seven motive types of homicide to determine which, if any, of them clustered and spread from one place to another over time.

Of the seven types of homicide we examined, only gang-motivated homicides displayed a pattern of clustering and spreading through Newark, NJ. However, while drug-motivated and revenge homicides did not spread, they did cluster in the same general geographic areas during much of the same time that gang-motivated homicides clustered together.

Medical Research: What should clinicians and patients take away from your report?

Dr. Zeoli: The co-occurrence of gang-motivated, revenge, and drug-motivated homicide clusters suggests that there may be common precipitating or facilitating factors in those areas that give rise to these types of homicide. A facilitating factor may be the presence of firearms – over 87% of drug-motivated, revenge, and gang-motivated homicides were committed with firearms. There may also be subcultural factors at play in these areas that make people more likely to resort to severe violence.

Medical Research: What recommendations do you have for future research as a result of this study?

Dr. Zeoli: Our study focuses on the modeling of homicide of homicide diffusion across space and time. It is a dynamic model that shows the movement of homicide within a city. By knowing that gang-motivated homicide diffuses, and that other types of homicide may cluster with it, we can further study the “susceptible” conditions that allow the homicide contagion to move into an area, and the protective conditions that keep it out of other areas. By identifying these conditions, we may be able to better predict spatial and temporal patterns of homicide in other cities with similar conditions.


April M. Zeoli, Sue Grady, Jesenia M. Pizarro, Chris Melde. Modeling the Movement of Homicide by Type to Inform Public Health Prevention EffortsAmerican Journal of Public Health, 2015; e1 DOI:2105/AJPH.2015.302732 is not a forum for the exchange of personal medical information, advice or the promotion of self-destructive behavior (e.g., eating disorders, suicide). While you may freely discuss your troubles, you should not look to the Website for information or advice on such topics. Instead, we recommend that you talk in person with a trusted medical professional.

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April M. Zeoli, PhD, MPH (2015). Gang Violence Spreads Like An Infectious Disease 

Last Updated on August 14, 2015 by Marie Benz MD FAAD