A 28-year-old woman is admitted to a local hospital emergency room complaining of sharp chest pains on her right side. The examining physician sees that the pain is especially acute when the woman tries to take a deep breath. Over the last 48 hours, the woman has had chills and muscular aches, as well as coughing. Moreover, she has just returned to the U.S. on a 16-hour flight from Rome, during which she was essentially immobile.