A foster mother allegedly raped a boy in her care more than 500 times – even claiming she was his girlfriend suffering from a premature ageing disease, a court has heard.

Married Joelle Barozzini allegedly raped the boy, who was 16 when he began living with her, while she was working for an agency that deals with troubled youth in Greensburg, Pennsylvania.

The 46-year-old is charged with rape, institutional sexual assault, corruption of minors and endangering the welfare of children.

The abuse was said to have taken place between 2009 and 2013 with the victim, now 24, testifying during a preliminary hearing that the pair had sex "hundreds of times".

According to CBS the victim said he did not tell anyone about the alleged abuse saying: "I was worried I'd get thrown away again."

The court heard how Barozzini allegedly had sex with him in several rooms at the house and in hotels.

She is also accused of referring to their relationship as that of boyfriend-girlfriend and sending him nude photos and giving him alcohol.

"I was honestly too nervous to say no," he said according to the Review-Tribune. "Every single time, just about, would be against my will."

Barozzini also allegedly told people she had a disease which caused premature ageing to pass herself off as the boy's girlfriend even creating a fictitious Facebook profile of his girlfriend.

The court also heard that Barozzini once had sex with the boy in the bedroom while other members of the family were in the home.

He told a court about the first occasion that the abuse started inside the family home: "I was nervous. She kissed me. She grabbed me by the hand and pulled me into her room.

"I was just really scared that somebody was going to see. I was kind of frightened. I really didn't know what to do."

The victim claimed that he had tried to tell a relative about the sexual abuse but they did not believe him. The allegations surfaced after a state trooper made a ChildLine report in November 2016.