Young Tyaisha Cox, who was killed last summer in a road traffic accident, did not die in vain according to an American family whose son is alive today thanks to a transplant of one of the girl's organs.

A letter from the boy's family was recently forwarded to Tyaisha's family by the transplant bank, thanking the family and saying their son now has a “new vitality”.

“I am also in awe of you decision to donate, your concern for other suffering children at such a difficult time in your own life and your resolve to create something positive out of such a tragedy,” said the letter from the nine-year-old boy's mother.

The letter said Tyaisha was their “guardian angel” and that their son Malcolm, who suffers from cystic fibrosis, had been on a transplant waiting list for 15 months before this life saving gift came through.

Tyaisha's mother, Margret Moore told The Royal Gazette that the letter came at a time when she was experiencing an emotional low point.

“I was feeling really low when the letter arrived,” she said. “When I was reading it, I was crying, my husband had to finish reading it for me. It's something good out of something bad.”

Tyaisha, who would have been seven years old on February 26, was knocked down while walking on a pedestrian crossing on her way to summer day camp at Purvis Primary, on August 7 last year.

Mrs. Moore said she was deeply moved by the letter from Malcolm's mother.

“It came at the right time though, because his family had written it in August and it arrived in January, because it passed through the New England Donor Bank,” she said.

“It felt good that someone else had benefited from her death and also took the time to write to say thank you.”

Mrs. Moor said the donor bank has sent thanks from all the other families whom Tyaisha's organs had gone to help, but that this was the first actual letter she had received.

Malcolm's mother, Jennifer, said that before he received Tyaisha's liver, it was thought that he would die, as the cystic fibrosis had caused a condition called cirrhosis, which is an irreversible damage to the liver.

The letter said: “The cirrhosis caused two extreme internal bleeds, which caused him to vomit up over 50 percent of his blood on two occasions.

“These types of bleeds are massive, occur very quickly, and are life threatening. He had to be rushed to the hospital for blood transfusions and spent weeks there recovering.”

Malcolm also underwent medical procedures every eight weeks to try to stop the bleeds from happening.

“The hope was that by tying off these veins, the blood would find alternate, less dangerous routes to use to bypass the clogged liver,” the letter said.

Malcolm was desperately in need of a new liver, he was very lethargic, he never wanted to play outside and he rarely smiled or laughed.

“He felt awful all the time and went to sleep most nights worrying about death and about bleeding again,” the letter said.

But after undergoing an 11-hour operation to replace his damaged organ, his mother said he had a new vitality.

The letter said, Malcolm asked: “Mom can I lay in the grass? I haven't lain in the grass in so long.”

It continued: “Were it not for your generous decision to donate your child's organs, my son may still be a very, very sick little boy.

“I cannot begin to imagine the pain you are feeling at this time, and I am so sorry for the loss of your baby and for all the hurt that you must be feeling.

“There have been some dark times with Malcolm's health when I have indeed had to imagine what I would do, how would I go on, what life would be like and I am just so terribly sorry that you are living that right now.

“I am also in awe of you decision to donate, your concern for other suffering children at such a difficult time in your own life and your resolve to create something positive out of such a tragedy.

“Please know that we have your baby, yourself, your family and community in our thoughts and prayers every single day, and we have lit a candle that burns here at our home for your angel.

“Your angel is now our angel too, Malcolm's guardian angel.”