US doctors have warned of a mysterious rare polio-like disease in California where up to 20 people have been infected.
A meeting of the American Academy of Neurology has heard that some patients had developed paralysis in all four limbs, which had not improved with treatment, reports BBC Online.
The US is polio-free, but related viruses can also attack the nervous system leading to paralysis.
Doctors say they do not expect an epidemic of the polio-like virus and that the infection remains rare.
Polio is a dangerous and feared childhood infection. The virus rapidly invades the nervous system and causes paralysis in one in 200 cases. It can be fatal if it stops the lungs from working.
Global vaccination programmes mean polio is endemic in just three countries - Afghanistan, Nigeria and Pakistan.
Polio-like
There have been 20 suspected cases of the new infection, mostly in children, in the past 18 months,
A detailed analysis of five cases showed enterovirus-68 - which is related to poliovirus - could be to blame.
In those cases all the children had been vaccinated against polio.
Symptoms have ranged from restricted movement in one limb to severe weakness in both legs and arms.
Dr Emanuelle Waubant, a neurologist at the University of California, San Francisco, told the BBC: “There has been no obvious increase in the pace of new cases so we don’t think we’re about to experience an epidemic, that’s the good news.
“But it's bad news for individuals unlucky enough to develop symptoms which tend to be moderate to severe and don't appear to improve too much despite reasonably aggressive treatment.”
