The assault came to light after the girl, staying with her mother, brother and grandparents, told about the abuse to one of her relatives 10 days ago, the police said.
According to the Union Ministry of Health and Family Welfare, Kerala has currently 67,903 active cases with 8,96,668 recoveries and 3,867 deaths so far.
Kerala recorded 76.38 per cent voter turnout in the 2nd phase of local body elections held in five districts, last week, according to the state election commission.