This symposium looks at the challenges of controlling an emerging disease agent with multiple transmission vehicles and means of delivery. Through better surveillance, norovirus has been identified as a major global pathogen affecting both the food and health-care industries. It causes about 90 percent of epidemic nonbacterial outbreaks of gastroenteritis around the world and may be responsible for 50 percent of all food-borne outbreaks of gastroenteritis in the United States. Large outbreaks can occur in restaurants, cruise ships, nursing homes, and child care centers. Norovirus has a very low infective dose and can be transmitted though food workers and the food production environment, person-to-person contact, and aerosols. Stools and vomitus of individuals who are ill may contain billions of infectious particles, which hand washing cannot completely eliminate. Even individuals who are recovering or are asymptomatic can excrete the norovirus for many days or weeks. Alcohol gels and wipes are not effective disinfectants. Exclusion of workers might be possible in theory, but difficult to impose in practice. An infected person can suddenly feel ill and experience projectile vomiting, which delivers the virus long distances and is difficult to clean up. Outbreaks have been traced to sick chefs, infected children in schools and childcare settings, and contaminated mothers cleaning up after a diaper-changing episode. A vaccine may be possible in the future.