BRANTFORD, July 2 -- The bat left no mark. That is the detail Dr. Brian Hummel keeps returning to when he describes the death of an 11-year-old boy who woke up one night in the summer of 2024 at a family cottage in northern Ontario to find the animal pressed against his nose and mouth. He swatted it away. His father caught it in a cooking pot and released it outside. No blood, no puncture, no scratch anyone could find. Nineteen days later, the boy was dead.

His parents did what most parents would do. They checked his face, saw nothing, and decided a bat that had not behaved erratically and left no visible wound was not worth a hospital visit. Rabies was not the first thing on anyone's mind, or the second. Nearly three weeks later, the bo...