Cause of mystery polio-like illness found

A virus called Enterovirus D68 may be the cause of a mysterious polio-like illness that has paralysed children in the US, Canada and Europe, scientists say.
Researchers at University of New South Wales (UNSW) in Australia analysed the scientific literature on the condition known as acute flaccid myelitis.
"In 2014, children in the US began to be diagnosed with a mystery illness that caused a polio-like paralysis," said Professor Raina MacIntyre of UNSW.
"More than 120 children developed the condition, known as acute flaccid myelitis, in the US alone but experts were baffled as to the cause," said MacIntyre, who led the study published in the journal Eurosurveillance.

That same year there were also unusually large outbreaks of infection with Enterovirus D68, or EV-D68 - a virus known since the early 1960s to cause runny noses, coughs, muscle aches, fever and difficulty breathing.
About 2,280 people in the US, Canada and Europe were infected with the virus, many of them children, and their respiratory symptoms were more severe than usual, researchers said.

Clusters of the paralysing illness, also mostly in children, were reported in the same regions, they said.
"This raised the possibility of a link between EV-D68 and acute flaccid myelitis. However, the virus had never been known to cause paralysis before," said MacIntyre.

The team applied the Bradfield Hill criteria - a set of nine principles developed to determine causality. The method used to prove that smoking caused cancer is now an accepted tool to determine causality.
"We are first to use his approach to analyse the relationship between EV-D68 and acute flaccid myelitis. Our results show that it is very likely that EV-D68 is the cause of the mystery illness and the paralysis of children," said MacIntyre.
"The incidence of EV-D68 infections is increasing worldwide, and a genetically distinct strain has recently evolved.
"There is no treatment or vaccine for the polio-like illness caused by EV-D68, which makes it important to act quickly to stop outbreaks," said MacIntyre.