No links established between cases in emergence of cluster of cases of polio-like disease that appears to cause paralysis.
A close-up of a polio virus. Two children in California have been identified with enterovirus-68, which is from the same family. Photograph: Dennis Kunkel Microscopy, Inc
Doctors are perplexed by the emergence of a cluster of cases of polio-like disease in children in California who appear to have suffered paralysis in one or more limbs.
Up to 20 suspect cases have been reported, although some are still being investigated. Five will be the subject of a presentation at the forthcoming American Academy of Neurology conference in April.
But so far, no links have been established between the cases, which experts say is not polio itself. Two children have been identified with enterovirus-68, which is from the same family of viruses as polio.
Dr Keith Van Haren at Lucile Packard Children’s Hospital at Stanford University warned that any child showing a sudden onset of weakness in their limbs or symptoms of paralysis should be immediately seen by a doctor. “The disease resembles but is not the same as polio,” he said. “But this is serious. Most of the children we’ve seen so far have not recovered use of their arm or their leg.”
“This is definitely not polio,” said Dr Robin Luff, chairman of the expert health panel of the British Polio Fellowship. “However one of the recurrent themes in the discussion is the repeated emphasis that polio is potentially still around and not to lower our guards.”
Because paralysing disease does not have to be reported by doctors, unlike polio, it is difficult to know whether this is just a randomly occurring cluster of cases that would not have been noticed if they had been geographically spread out, said Luff. Paralysis can be caused by a number of viruses, including adenoviruses as well as enteroviruses.
Enterovirus-68, which is very rare, “is mostly associated with fairly benign upper respiratory infections – coughs and colds,” said Luff. “It is reported to cause occasional cases of paralysis.”
Because it is transmitted by water droplets in coughs and sneezes, it should be more easily transmitted than polio, which depends on the oral-faecal route. Yet only about 20 cases have been reported – not all of them confirmed and possibly not all in children – in the course of a year.
Polio was eradicated decades ago from the US and the UK, but vaccination of infants is still very important because of the danger that it could be reimported. There are just three countries in the world where the disease is still endemic – Afghanistan, Pakistan and Nigeria – but cases sporadically occur when people travel. The ease with which polio can return to an area that was free of it was recently shown by an outbreak in Syria.