“It was an indescribable, unspeakable scene”, that greeted police who were called to the house in Flers in northwestern France last Friday, said prosecutor Hugues de Phily.
He said the girl's mother called emergency services when she realized her child was “in a critical state”.
Police found the emaciated girl in a coma, her body smeared with excrement and carrying infected wounds, some containing maggots, in a room also covered with faeces and trash, said Phily.
Her lower body was swathed in several layers of clothing and her top was naked.
“Everyone who saw the scene was affected,” the prosecutor said.
The girl's parents were “incapable of explaining in a coherent manner how they let their daughter get into such a state without intervening”.
Neither was it clear how they managed to live in the adjoining rooms permeated by the stench from their daughter's room.
Phily said the parents showed no apparent psychological problem, but displayed “enigmatic behaviour”.
The father, born in 1968, was jobless. The mother, born in 1971, who has a job, indicated she would go “from time to time” to give her daughter food.
The two were charged on Sunday with failing to help a person in danger.