MEDICAL MYSTERY: Something in the Man’s Bed Was Making Him Sick. “The patient was surprised by this question, but it ended up being the right one: During the past year, the man had gotten a feather blanket and pillows. When the patient returned to the hospital, Dr. Dempsey ordered a chest X-ray and performed a more specific blood test. It showed that the man had antibodies to bird feather dust, and the X-ray was consistent with a condition called hypersensitivity pneumonitis, a term used to describe lung disease caused by an allergic reaction to aerosolized bacteria and fungi. Or in this case, dust from duck or goose feathers found in bedding.”