Researchers at Purdue University have found a new polio-like virus that is causing paralysis in kids in the US. Courtesy: YouTube/Purdue University

A MYSTERIOUS new disease is afflicting children in the United States. It starts as a cold — but ends as weakness and paralysis. Does polio have a twin? Or are several new, potentially debilitating, viruses on the loose?

In the past 12 months, more than 118 children across 34 US states have been reported with a condition called “acute flaccid myelitis”.

It’s a condition that seems to start out as a respiratory infection like a serous bout of the common cold.

In these cases the muscle pain doesn’t go away. Then they lose their strength in their arms and legs.

While such symptoms are enough to panic any parent, disease experts say the cause does not appear to be particularly infectious.

But the number of cases seeking hospitalisation in the US has raised eyebrows.

Early suspicions have fallen on the viruses which belong to the family we know as the common cold, the rhinoviruses.

The Centers for Disease Control and Prevention (CDC) have named enterovirus D68 (EV-D68) as the chief suspect.

But new figures show only 20 per cent of the known cases in the US tested positive for D68 — and it isn’t certain if this virus is linked to the paralysis anyway.

“But it is a big family of viruses,” says infectious disease expert Associate Professor Sanjaya Senanayake of the Australian National University. “Within that family you can get a virus that is more serious, and every so often we see large numbers of people being infected with a nasty virus which can do anything from not even making you sick through to the other extreme where they get brain type infections and can even effect the nerves and cause paralysis.”

D68 — a little active virus first diagnosed in California more than 50 years ago — may soon be let off the hook.

A new study of one paralysis sufferer has narrowed down another contender.

PATIENT ‘ZERO’

Dr Ronald Turner of the University of Virginia has published a report on an otherwise healthy six-year-old girl who, her family thought, had simply caught the common cold.

Last year she developed a fever. But that and other cold symptoms cleared up as usual.

But her aching limbs remained.

Her shoulders began to droop.

After two weeks, she began having difficulty using her right hand.

According to the study to be published in the October 2015 edition of the journal Emerging Infectious Diseases, she was taken to the University of Virginia Children’s Hospital.

She did not have the D68 virus.

After proving unresponsive to treatments, she tested positive for a new virus — C105.

It’s a recently discovered virus belonging to the same lineage as polio.

It is the first recorded case in the United States of a virus only identified within the past five years.

Eight months later, the paralysis victim has reportedly almost fully recovered her strength.

EMERGENT STRAIN

Enterovirus C105 is something new. It was first detected in patients from Peru and the Republic of Congo in 2010. The Congo case also suffered paralysis.

It’s now thought to be circulating worldwide.

Dr Turner says his six-year-old patient may simply be the first known case in the US because the C105 virus is particularly hard to detect.

Dr Senanayake says its ties to polio makes guilt by association understandable.

What makes the polio virus different — and deadly — is that it is highly contagious. A century ago, polio paralysed hundreds of thousands of children every year. But it infected many more.

“This is one group of infections we’re always aware of and keeping an eye on as enteroviruses are always circulating,” Dr Senanayake says. Viral meningitis — the inflammation of the brain and spinal cord — is most commonly caused by an enterovirus.

But there is still a considerable body of research needed before C105 can be identified as the disease behind the new paralysis outbreak.

Magnetic resonance imaging of the six-year-old girl showed “abnormal hyperintensity” in her spinal column. But tests of her spinal fluid have so far not detected the presence of C105 there.

The potential remains for it to be a third, as yet unidentified, virus that just happens to be co-infecting victims at the same time as C105 and D68.

Or it could be linked to all of them.

“Sometimes our immune system can be a bit overactive and cause problems,” Dr Senanayake says. “With these recent cases of paralysis in these children, they’ve never found a virus in the spinal fluid. So one thought has been could it be that the virus has caused an infection elsewhere in the body and the immune system has got excited about that and ended up causing some damage to the nerves.”

In this outbreak, the cause — whatever it may be — is not showing any signs of becoming a pandemic.