Steven Girgenti, worldwide chief executive of Healthworld Group, will assume leadership of the new agency formed by the merger of Healthworld and Ogilvy Healthcare, both WPP companies. The new entity will be known as Ogilvy Healthworld, and the merger will be completed by the end of 2004, the agencies reported this week. Margot James, head of Ogilvy Healthcare Europe, will become regional president of Ogilvy Healthworld Europe. She reports to Girgenti.