When Evie Clark was struck down with a runny nose, cough and a temperature on Christmas Day, her parents assumed she just had a cold.
But by New Year's Eve the seven-year-old had been left wheelchair-bound in hospital by a mysterious condition that temporarily paralysed her.
Evie, of Maidstone in Kent, is one of dozens of British children who developed a condition called acute flaccid myelitis last year, which is thought to be caused by a common virus.
Her mother, Nicola, said it was 'heartbreaking' to watch her daughter suffer from an illness neither she nor many of the doctors they saw could understand.
Despite having mostly recovered following almost a year of physiotherapy, Evie has been left with a 'sleepy' left arm and struggles to use it.
Doctors now say she needs complex surgery to restore nerve connections in her limb to help it heal completely.
Evie Clark (pictured this summer) first became ill at Christmas last year with what her parents thought was a cold, but her condition quickly deteriorated to the point she couldn't hold up her own head
Evie, pictured on her first bike ride after she was discharged from hospital in February, has made a good recovery but surgeons want to operate to try and improve the function in her left arm
Evie's case is one of a total of 57 diagnosed across England since January 2018.
Public Health England has recorded a spike in cases of acute flaccid paralysis – the crippling symptom of acute flaccid myelitis (AFM).
Almost all the cases happened during a surge in October, November and December last year and there were more than twice as many as in the past nine years combined.
Because of this, Public Health England last winter launched a taskforce to work out what causes AFM and how to treat children who are affected.
The reasons behind it are unclear – although a virus called EV-D68 is a prime suspect – and symptoms seem to vary from patient to patient.
The term 'myelitis' means inflammation of the spinal cord.
Transverse myelitis is the broad name of the disease, and there are various sub-types.
It is a neurological disorder which inflames the spinal cord across its width ('transverse'), destroying the fatty substance that protects nerve cells.
That can lead to paralysis.
AFM is an unusual sub-type of transverse myelitis.
Patients starts with the same spinal inflammation, but their symptoms are different and the disease develops differently.
The main distinction is that AFM patients are weak and limp, while patients with general transverse myelitis tend to be rigid.
Most AFM patients start to struggle with movement of the limbs, face, tongue, and eyes.
They then begin to lose control of one limb or sometimes the whole body - though many maintain control of their sensory, bowel and bladder functions.
Unlike transverse myelitis, which has been around for years, doctors are still in the dark about why and how AFM manifests itself.
Officials at PHE called the illness 'severe' and said most patients are left with serious long-term issues.
Evie, the youngest of a family of four children, first became ill on Christmas Day last year with a cough, runny nose and a temperature, so her mother kept a close eye on her.
'She was flinching in her sleep and breathing fast,' Mrs Clark, 44, told MailOnline.
'When I was in her bed one day she was really flinching and her back was really hurting her. I thought she had spent too much time lying on the sofa or something.
'But she couldn't lay still and she was really unsettled with the back pain. Then she went to the toilet, came back and said "my arm doesn't work".'
By this time, Mrs Clark and her husband Geoff, a 44-year-old electrician, realised something was seriously wrong so took her to hospital.
Soon, their daughter didn't have the strength to look down to touch her chin to her chest, and her arm had become so painful she screamed when people touched it.
The A&E doctor in Maidstone referred her to another hospital, where she stayed for two days, but medics then sent her into central London to the Evelina Children's Hospital some 40 miles (64km) away.
Doctors in Kent had made sure Evie hadn't had a stroke or a spinal injury but couldn't understand why she was losing the use of her arms and legs.
Evie (left, pictured with her siblings and parents on holiday in 2018) is the youngest member of her family, who live in Maidstone, Kent
Pictured in hospital, the now seven-year-old ended up in so much pain she would scream every time someone touched her, her mother said
Enterovirus-D68 (EV-D68) is a type of non-polio causing virus.
It was first identified in the US in 1962 but numbers were low. It has become increasingly common over time but is hard to keep track of because most cases aren't recorded.
Many people infected with the virus don't develop any illness, while those who do generally only get a runny nose or cough.
However, it can cause more serious breathing problems and scientists now believe it may be a trigger for acute flaccid myelitis, a condition which triggers swelling in the spinal column and causes paralysing nerve damage.
EV-D68 is believed to spread the same way cold and flu germs do – through the coughs and sneezes of other infected people.
Children and teenagers are the most likely to become ill because adults have usually been exposed to them without problems already, making them immune.
EV-D68 infection can only be diagnosed with specific lab tests and there is no cure for illness caused by it.
Source: Centers for Disease Control and Prevention
'She was in a hell of a lot of pain,' Mrs Clark said.sonos sonos One (Gen 2) - Voice Controlled Smart Speaker with Amazon Alexa Built-in - Black read more