(KTVI) – Fans of Laura Ingalls Wilder's Little House On The Prairie books are familiar with Laura's older sister Mary going blind.
Now a new explanation says scarlet fever may not have caused her vision loss.
Pediatrician Dr. Kathleen Berchelmann with St. Louis Children's Hospital explains this latest research.
Researchers say meningoencephalitis, an inflammation of the protective membranes covering the brain and of the brain itself, could explain both the blindness and Mary's other symptoms: fever, headaches, weakness and facial paralysis.
In the 1800s, doctors believed scarlet fever caused blindness, and often misdiagnosed other illnesses as scarlet fever, causing much confusion.