Doctors treating Ava Stark have found a possible stem cell donor who could save her life.

The brave three-year-old, who relies on weekly platelet transfusions to keep her alive, faced dying from a rare blood disorder unless a perfect donor match could be found.

News of the little girl's plight sparked a worldwide search for a candidate after her first match - the only one found on a 25 million-strong global donor register - had to pull out at the last minute.

Ava's family, from Lochgelly in Fife, launched a desperate plea on social media to find a replacement and the Save Ava campaign encouraged more than 11,000 would-be donors to sign up across the UK.

Prior to the appeal, there was only one 10 out of 10 match from the entire register, which includes 50 countries.

But on Friday, staff at the Sick Kids Hospital in Edinburgh were able to phone Ava's mother to tell her the good news that a new donor had finally been tracked down.

"Marie called me as soon as she found out and it was overwhelming," says Ava's grandmother, Agnes Sutherland.

"We just couldn't believe it. The response from the public has been magnificent and we just can't thank everyone enough."

It has been a tough journey for the little girl who caught every bug, cold and flu going and even got foot and mouth and impetigo before doctors diagnosed her.

In March, Ava had brought up a blood clot through her nose and was rushed to Kirkcaldy's Victoria Hospital by ambulance when she started throwing up blood.

After going through an emergency blood transfusion, Ava was transferred to the Sick Kids in Edinburgh where doctors spent two weeks trying to discover what was making the little girl so sick.

When the rare diagnoses of inherited bone marrow failure came through, her family was told she desperately needed a bone marrow transplant to survive.

"When you look at her now, you would almost think there was nothing seriously wrong with her because she's so cheerful though," says her grandmother.

"She's a bubbly wee soul who's always on the move."

Ava's doctors now have a final general health check to get through with the new donor and hope to give Ava the healthy stem cells before the end of October.

She will undergo treatment over the next few weeks to suppress her immune system before the transplant takes place, staying indoors to make sure she doesn't catch any bugs while her body prepares for the treatment.

Until then, her family have transformed the house into a Santa's grotto of Christmas decorations and plan to spend time together every weekend playing games and celebrating an early festive season.

"She's my wee princess," says Agnes. "Marie and myself would like to thank everyone who stepped forward to help her. We can now start to look forward to Christmas together."

The little fighter still faces a huge battle as the survival rate for her condition is just 20 per cent, but her new donor will give her the best chance she needs.

And little Ava, who adores animals and Minnie Mouse, has apparently added one more entry to her list of favourite things.

"I've a donor," she says happily down the phone. "My hero."

Find out more about becoming a donor

Visit charity Anthony Nolan's website for more details on becoming a bone marrow donor and a free testing kit.