Philadelphia has a gun violence epidemic. What if it were treated like any other contagious disease?

Robert Warner and his crew don’t have medical degrees. But in the midst of Philadelphia’s gun violence epidemic, they are in the business of saving lives.

Day or night, Warner and his outreach workers are on North Philly streets mediating disputes, organizing basketball games between youth factions, dissuading folks from violence, and helping young people find jobs.

When someone gets shot, they’re in the hospital, helping the victim’s family, and on the street, preventing retaliation.

“I actually do think violence is a public health problem,” said Warner, director of Cure Violence, a global public health program for fighting street violence, with an operation run out of Temple University’s medical school. “Most of the time, the victims and the perpetrators don’t understand they’ve been traumatized — either seeing someone get shot or shooting someone. We have to educate the community more.”

Philadelphia is one of the deadliest cities in America. Last year, the city had 353 homicides, the most in more than a decade. So far this year, there have been 325 — up 6% from this time last year. Recent events are amplifying calls for action. In the last month alone, 12 children here have been shot, ranging in age from 10 months to 16 years. The most recent was a 16-year-old girl shot in the left shoulder late Saturday afternoon as she got off a SEPTA bus in North Philadelphia.

Experts are increasingly fond of saying that gun violence should be treated like a public health problem, like a contagious disease that will infect ever more people unless preventive measures are taken. But what exactly does it mean to take a public health approach to gun violence? And can this soft-sounding concept get traction amid demands to get tougher on crime?

Just as epidemiologists search for clues when there is an outbreak of E. coli or measles, preventing violence means identifying risk factors, developing data on the source and growth of the problem, and containing its spread, according to the federal Centers for Disease Control and Prevention.

Research shows that violence in a community has far-reaching effects, from victims who bear physical wounds to those suffering stress and anxiety from knowing they live in a danger zone.

“This is not somebody else’s problem,” said John Rich, co-director for the Center for Nonviolence and Social Justice at Drexel University, which provides support to victims. “Even if you’re not directly affected by violence, it could be having an indirect effect on your health. For example, the constant news reports give people a sense that they’re not safe, even if they’re not high-risk.”

There also is research showing that violence can spread, like any other contagion.

“There are good studies in the psychological literature that if people are exposed to violence, they’re more likely to be violent,” said pediatrician Kathleen Reeves, director of Temple’s Center for Urban Bioethics, which houses Warner’s program. “When an area has violence, it breeds more violence, and violence makes every other social determinant of health worse.”

» READ MORE: Gunshot victims suffer long after the physical wounds have healed

Gun violence resembles public health issues in other ways, too:

“Exposure to violence alters the functioning of your brain,” said Charles Ransford, senior director of science and policy at Cure Violence Global, one of the best known public health models for violence prevention, with global partners that include UNICEF.

The model includes training members of a high-risk community — often the formerly violent — to be so well-connected in a community that they can stop conflicts that are brewing before they turn bloody. Helping victims and perpetrators with counseling, education, job resources, and other needs are essential to the program, started by Gary Slutkin, a Chicago physician, epidemiology professor, and former World Health Organization official.

Results look promising. A 2015 study of New York City programs found that neighborhoods using the approach had an 18% drop in the number of homicides over three years, while comparable neighborhoods had a 69% increase. San Pedro Sula, a city in Honduras with one of the world’s worst rates of violence, saw an 88% reduction in killings and shootings in five zones of the city in 2015, according to one program review. And Trinidad and Tobago saw a 45% reduction in violent crimes in the capital, Port of Spain, after the program’s implementation, according to a study conducted by Arizona State University.

The Temple medical school program that Warner directs began in 2013 as Philadelphia CeaseFire. Using the Cure Violence approach, it was credited with a 30% reduction in shootings over two years in the North Philadelphia neighborhoods it targeted. It ended when federal funding dried up.

Temple has operated a smaller-scale operation, with a budget composed of university, city and state funds. Program leaders say in the last several months they have been expanding the program from hospital-based to more community outreach.

Using public health tactics to address violence is a key part of “the Philadelphia Roadmap to Safer Communities,” an ambitious five-year plan Mayor Jim Kenney’s administration unveiled in January. In recent months, the city approved an infusion of $37 million over that period to fund the plan’s various initiatives, including policing measures, social services, mental health and mentoring interventions, anti-blight programs, more financial support for grassroots groups, school partnerships, employment and education programs, and a vow to track the results with data.

» READ MORE: After bloody 2018, Philadelphia unveils gun violence plan

The Community Crisis Intervention Program (CCIP), a homegrown initiative somewhat similar to Temple’s program, is part of the plan.

“I call it my boots on the ground,” said Vanessa Garrett Harley, deputy managing director for criminal justice and public safety, and chief supervisor of the five-year plan. CCIP workers — like those in the Temple program — are hired in part because they have similar backgrounds as the people they are trying to reach. Garrett Harley said they have already proved helpful in addressing needs in neighborhoods with recent shootings and brewing conflicts, including in North and Southwest Philadelphia.

The program soon will expand from 24 to 35 full-time workers active in several high-risk parts of the city, and is getting $2.5 million this fiscal year.

Whether the newly devised CCIP program will be more successful than the better-established Cure Violence model won’t be apparent until the city has collected and published data on its results.

Cure Violence programs are careful to remain separate from police, in order to build community trust. But given Philadelphia’s anti-snitching culture, Theron Pride, city senior director of Violence Prevention Strategies and Programs, said CCIP needed to be a little different in that regard.

Community members, said Pride, have said they won’t share information with police because they are worried about their personal safety if they do. But they might talk to a CCIP worker, who could then talk to police. Results will show whether that degree of separation helps overcome the anti-snitching culture.

Cities that use the public health model to curb violence can also remain committed to traditional law enforcement and criminal justice measures, noted Ransford, of Cure Violence.

He estimated it would likely cost $15 million to $20 million to implement the Cure Violence model throughout Philadelphia. That could mean most of the city’s budget for its five-year plan, which also includes more policing, clearing vacant lots, increasing streetlights, partnering with the city schools, and more.

» READ MORE: Gun violence is costly. So is responding to it in the wrong ways

“It’s not about one program," Ransford said. "It’s really about an approach that the city is going to take a health approach to violence.”

At Children’s Hospital of Philadelphia, Joel Fein, director of advocacy and health policy in the emergency department, co-directs the hospital’s Violence Prevention Initiative, which helps families get support after surviving violence. Despite recent events, he said there is cause for optimism — provided enough attention is paid to timely interventions, and they are applied patiently and consistently for many years.

“I can say that I’m going to enhance a young person’s diet with lots of fruits and vegetables, but I won’t know for a while what difference that makes, because kids don’t develop cardiac disease,” he said.

When it comes to the disease of violence, “the most important thing is that we, as a community, can agree that these are difficult problems, but we are prepared to take the long view.”