By Michelle Roberts
BBC News health reporter
Bethany Cain was just a month away from turning four when she died unexpectedly last September.
Bethany died from a complication of food poisoning
Her father, Paul, from Ormskirk, Lancashire, decided he wanted doctors at Alder Hey hospital, where she died, to carry out a post-mortem examination.
"When Beth died, it was such a shock. There was no warning. It came from nowhere.
"She had only started out with a tummy ache. No one had expected it, not even
the staff. They were as stunned as us."
Bethany became ill with food poising while the family were on holiday in Scotland.
"She was just a bit poorly. We thought it would just be a short-term thing. She had never really been ill before, apart from the odd cold. just like any other child."
Within the next few days her condition got rapidly worse, and she was admitted to hospital.
When she began to develop complications, she was referred to Alder Hey hospital.
Paul said: "Within 10 days of her getting ill she was dead.
"There had to be a post-mortem because we did not know what it was that had killed her. We didn't mind when the doctors told us that because when your child dies, you need answers.
"And it was not just to give us answers. It can also help stop the same happening to another child," he said.
The post-mortem revealed that Bethany had died from a rare complication of her E.coli infection, called Haemolytic Uraemic Syndrome.
People who develop HUS have problems with their blood. Some of the blood cells are killed off, so they become anaemic and their blood cannot clot properly.
This can damage the internal organs and lead to kidney failure and death.
Paul said that, throughout the entire process, the staff at Alder Hey were fantastic.
"They were so supportive. They explained everything that was happening every step of the way.
"I'm a student nurse so I know a bit about the system. But they treated my like a parent and a father.
"Afterwards, we wanted to speak with the doctors who looked after Bethany. They arranged that. Anything we wanted support with, they were willing to offer.
"They came to see us, sent letters and came to the funeral. One of the nurses even gave us her home phone number in case we needed to chat. It was way beyond the call of duty."
Paul said that although you never get over the loss of a child, he and Heather are trying to be strong.
"We don't know for sure how Bethany caught the bug, but we think it could have been from playing and getting dirty hands.
"Nothing can bring Bethany back, but you have got to try and be positive.
"You have to remember the good times, look back with fondness and appreciate the times that you had with them.
He said he hoped that Bethany's death would mean that other children would not die of the same condition.
"If there is one message that I would want to get across to other parents, it is 'wash your child's hands before they eat'.
"Not just a quick wipe, but properly."