This paper sheds light on the recent spike in communal violence in India by theorizing unorganized violence as an epidemic. The basic premise is that riots, lynching, xenophobic assaults, and forms of spontaneous and uncoordinated violence spread rapidly when states fail to contain the initial violent events. Poor quarantine i.e. inadequate state response catalyzes the outbreak among the observers with variable predisposition to violence. Some of them are more vulnerable than others due to a combination of several unit-specific and system-specific factors. Each event generates a pathogenic template of action i.e. a heuristic containing information about the event and the ensuing sanctions. Lower probability of sanctions increases the likelihood of violence. Repetitive exposure to violent events cements the template in the minds of the observers, and the heuristic is involuntarily activated when they nd themselves in a situation they had vicarious observed. I use a novel dataset on cow-related violence in India to show that a violent heuristic around a common object of contention spreads like an epidemic in the absence of satisfactory police response. I also identify other cases where this analogy can be applied to increase our understanding of how violence spreads.