Think about gang violence as an infection, and you won’t make do with treating the symptoms by trying to reduce the number of guns on the street, jailing high profile gang members, or even instituting anti-drug curricula in the schools. You find where the violence starts and try to keep it from spreading.

This is the perspective of Gary Slutkin, an epidemiologist and physician who has worked to stop the spread of infectious diseases in African. He has drawn on his public health background to design CeaseFire, a program for curbing gang violence in Chicago.

Aspects of CeaseFire’s goals are conventional enough: it aims to change the culture of violent neighborhoods by working with influential community members, staging anti-violence demonstrations, and posting anti-violence signs around neighborhoods.

More unusual is CeaseFire’s approach to gang members. Staff work on the streets more often than in offices, finding and forming relationships with violent gang members, whom the program treats them as rational actors rather than as immoral or dysfunctional.

The idea is to emphasize the costs of violence and to clear a pathway to new type of life. Some CeaseFire staff help clients get jobs, high school degrees, and even more mundane things like driver licenses. Others, called “violence interrupters,” aim to stop the escalation of violence.

Many CeaseFire interrupters grew up in the neighborhoods where they are assigned. They are usually former gang members, so they have a lot of credibility with their clients. Their title speaks to what they aim to do: to interrupt cycles of violence and retaliation, again by appealing to reason (although not always the law). Interrupters might, for example, convince gang members, hungry for revenge after a shooting, that warfare is bad for their drug business and may attract a police crackdown.

A team of researchers from the Institute for Policy Research, Northwestern University, Chicago, headed by Wesley Skogan, carried out an evaluation of CeaseFire-Chicago by interviewing staff and clients as well as members of the communities targeted by CeaseFire and observing staff meetings.

They then used statistical models to compare CeaseFire sites to similar communities that did not participate in the program to assess its impact on violence. Their findings suggest that CeaseFire helped to significantly reduce the number of shootings, increase the safety, and curb cycles of retaliation in most of the seven sites they studied.

The research team’s report details funding and political difficulties that have plagued the program since it’s inception as well as the challenges to assessing its impact. However, the potential of the program to rein in violence, despite these problems, appears clear.

• Summary of “Evaluation of CeaseFire-Chicago” by Wesley G. Skogan, Susan M. Hartnett, Natalie Bump and Jill Dubois, May 2008, Institute for Policy Research, Northwestern University, Chicago, Illinois, USA, funded by the US Department of Justice.