Epidemiologists will be busy this summer sifting through sewage and social media with the goal of keeping soccer fans and the public safe from severe illness during the World Cup , one of the largest and most globally diverse mass gatherings ever anticipated. A ​public health squad based in Washington, D.C., plans to monitor wastewater and internet chatter to detect and track infectious diseases should they emerge in any of the ‌U.S. or Canadian cities hosting World Cup players, their matches,