The patient hadn’t eaten anything substantial for years due to nausea so constant that she couldn’t keep down solid food. Instead, she “ate” daily through an IV line. When asked what food she missed she said none: The very thought made her sick to her stomach. Then there was the dizziness and the mysterious fevers — spiking to 106 degrees Fahrenheit at times — caused by bloodstream infections that struck without warning and that, when the doorbell rang, made her wonder whether she would make it through an otherwise routine visit with friends. Now 23, she felt like it was an eterni...