"We were finally a family and the excitement and anticipation of this new bundle of joy started to set in as we began what we thought would be a normal journey as parents," John wrote on the couple's blog, set up in memory of their daughter.
"From the moment she came home she was such a little joy, so placid and relaxed and for the remainder of that week seemed to settle into her own routine quickly."
When she was assessed by a nurse at home later that week she was deemed a happy, healthy baby.
But two days later, she was "out of sorts". By that night, she was hard to settle and hadn't fed much.
According to John, by the following morning she had settled and was back to sleeping well.
"As the day went on it appeared she was a bit congested as if she had caught a cold. She was not distressed in any way but a bit more clingy."
Then her parents watched as her colour changed before their eyes and she went limp.
She was rushed to hospital and at 1.09am she was pronounced dead.
Her body was handed back to John and his wife wrapped in a blanket.
A post-mortem revealed their daughter's rapid demise and death was caused by the Herpes Simplex Virus 1 (HSV-1), more commonly known as the cold sore virus.
In Eibhlin's case, she had contracted a more deadly version of the virus, known as Disseminated Neonatal Herpes Simplex Virus 1, which incubates in the body without symptoms and results in multiple organ failure.
While 90 per cent of these infections typically come from the mother, Louise was tested and found not to have the virus.
It was eventually discovered that Eibhlin had contracted it from the hospital where she was born.
According to John, "We know from tests that the virus was already in her system when she came home from the maternity hospital with us."
Devastated by their loss, John and Louis are working to raise awareness about the virus and its potentially deadly affect on infants.
The couple want to see policy changes made to prevent deaths like their daughter's and are campaigning for maternity welcome packs to include information on the virus.
They want Eibhlin's story told in antenatal classes, to have posters put up in clinics and medical students to be briefed about the virus too.