A puzzling outbreak of sudden liver disease in nearly 200 children has health authorities in several countries racing to find answers. The illness is being called hepatitis of unknown origin. The cases have no known connection, although a link with a virus that can cause colds is being investigated. At least one child died; several have required liver transplants. Cases include children aged 1 month to 16 years. Most cases have occurred in Europe. U.S. cases have been reported in Alabama, Illinois and North Carolina and doctors have been told to be on the lookout.