Cases of a rare illness that can cause paralysis have been confirmed in 22 US states.
At least 127 cases of acute flaccid myelitis (AFM), a neurological condition, have been under investigation by the US Centre for Disease Control this year.
It has been identified in 67 people, mostly children, so far.
Over 90 per cent of those affected are under the age of 18, with the average age being 4.
It causes the muscles and reflexes in the body to become weak or and in some cases paralysed. Symptoms can appear and severely worsen within a couple of hours.
It is also characterised by drooping or weakness in the face, trouble swallowing and slurred speech.
Because of these symptoms AFM has been likened to polio, which has been more or less wiped out in the western world thanks to vaccination.
The outbreak has been “frightening” for parents, said Dr Nancy Messonnier, director of CDC’s National Centre for Immunization and Respiratory Diseases.
“We actually don’t know what is causing this increase. For some of the previous cases we’ve identified one pathogen or another, but we have no unifying diagnosis.
“I encourage parents to seek medical care right way if you or your child develops sudden weakness or loss of muscle tone in arms and legs.”
This year’s cases have mirrored a pattern of AFM outbreaks in 2014 and 2016, which saw spikes in incidences of the disease in the autumn.
One child is known to have died from the illness in the US in 2017.
