A patient who has been "devastated" by the Strep A infection was sent home from A&E, her father has revealed.
Four-year-old Camila Rose Burns, who is in intensive care at Liverpool's Alder Hey Children's Hospital, spent six hours waiting in the emergency room last Sunday.
Her father Dean Burns said they were sent home after the wait, thinking it was "just a 24-hour sickness bug".
The four-year-old is now "fighting for her life" on a ventilator with the infection.
She was previously described by medics as "the poorliest girl in the whole of England".
Mr Burns told BBC Radio 4's Today programme: "On the Sunday morning when we got up, she just didn’t look right so we took her to the hospital.
"We were there for six hours, we returned home then Sunday afternoon she was laying on the couch just still.
"They thought it was a sickness bug…so we took her home."
He added that the doctor had given her "a steroid and an inhaler" but that by early Monday morning she was "laying in bed wide awake in her own vomit".
After rushing her back to A&E, he was told it had "progressed into something called iGAS [invasive Group A Strep]," which went straight into her bloodstream and "has devastated her whole body".
"I'm at a loss with it all to be honest with you, I just want my family back, the pain is unimaginable, she’s so beautiful, so precious, just my little girl," he added.
Strep A is a common bacterial infection which causes strep throat, tonsillitis and scarlet fever and is easily treatable with antibiotics.
But while it is a common infection it can also, in rare cases, lead to a severe condition called invasive Group A Strep (iGAS). Penicillin is the preferred medication of choice in the UK.
'We're concerned,' says chief medic
Dr Susan Hopkins, Chief Medical Advisor of the UKHSA, said the numbers of children with Scarlet Fever and iGAS are "much much higher than we have seen at this time of year for the last five years".
"So we’re concerned, and concerned enough to ensure that we wanted to make the public aware of the signs and symptoms that they should watch out for and of course to alert clinicians to prescribe antibiotics for these conditions," she said.
She warned that it can be "very difficult" for clinicians to spot the conditions and that they "worry about missing individuals with Sepsis and invasive bacterial infections".
"Being alert, taking the diagnostic test and considering whether the individual needs Penicillin is the right course of action," the clinician told the Today programme.
Asked why infections might be spiking at an abnormal time of the year, Dr Hopkins said that the return to normal social mixing and "out of sync" patterns of diseases with seasons are all contributing.
She said: "We need to recognise that the measures that we’ve taken for the last couple of years to reduce Covid circulating will also reduce other infections circulating.
"So that means that as things get back to normal, these traditional infections that we’ve seen for many years are circulating at great levels."