The girl, from the southern province of Qena, was found to be "very critical" and hospitalised "too late," health ministry spokesman Abdel Rahman Shahin told AFP.
Other officials had earlier said the girl had been in contact with poultry.
The highly pathogenic virus has killed 15 people out of the 35 cases reported to date in Egypt, with children the worst affected. The disease was first diagnosed in the country in February 2006.
Egypt's geographical location on major bird migration routes and the widespread practice of keeping domestic fowl near living quarters have led to it being the hardest-hit country outside of Asia.