The youngster was sleeping beside her mother on a pavement in Tirur, in southern India, when she was kidnapped.
The homeless family only noticed she was missing the next morning.
The child was found passed out in the street by students on their way to school.
One of the students said: "She had a high fever and she had ants crawling all over her body."
The girl is currently in intensive care, and doctors say it will take her months to recover.
Despite international outrage over the Delhi gang rape in December, more and more rape cases are reported every day - four a day in Delhi alone.
Indian activists protest for the implementation of harsher punishments for rape cases in New Delhi
The government is now trying to introduce tougher anti-rape laws.
Campaigners believe the rise in reported rapes is the result of more women coming forward to report crimes of sexual violence.
Women are increasingly scared to travel alone at night in the capital.
The city's only taxi service for women - which uses only women drivers - has said that business is booming.
Driver Kushi Prajapati said: "After the Delhi gang rape we've been busy day and night. Women feel very unsafe and they use our taxi service for safety reasons" -- These fcking savages have no heart, soul or feelings - they are not human - they are the spawn of Satan!! ... Fx