Box 1: Risk factors in the clinical history for potential human avian H5N1 influenza infection (adapted from ref 4) Travel to or residence in an area affected by avian influenza outbreaks in birds or other animals. Direct contact with dead or diseased birds or other animals in an affected area. Close contact with an H5N1 patient (living or deceased) or a person with unexplained moderate-to-severe acute respiratory illness. A possible occupational exposure, including employment as an animal culler, veterinarian, laboratory worker, or health care worker.