Blog dedicated primarily to randomly selected news items; comments reflecting personal perceptions

Monday, October 06, 2014

A Medical Enigma Within a Virus Mystery

"It seems pretty clear that this virus has changed in some way, and is now causing brand-new clinical manifestations. I think it's difficult not to be concerned about a virus that can cause a polio-like illness."
Dr. Joan Robinson, chairwoman, Canadian Pediatric Society infectious disease committee

"We know that children are a bit more at risk [for infection] and probably for respiratory problems, because they haven't been exposed to this virus before."
Dr. Bryna Warshawsky, Public Health Ontario

"It's very uncommon to see this type of neurological presentation happening in children."
"Every region across Canada and the United States is reporting a small but significant cluster."
Dr. Brandon Meaney, head, pediatric neurology, McMaster Children's Hospital, Hamilton

Yet another virus to contend with, one initially thought to be fairly innocuous -- and it does seem to be innocuous to many who contract it with few symptoms, or mild symptoms quickly thrown off - yet proving not to be in some patients, particularly young children. Public health officials had evidently cautioned doctors early in the fall to be wary of Enterovirus D68, a bug with cold-like symptoms beginning to present in surprising numbers.

The caution relates to its propensity to cause serious respiratory complications in a small percentage of young patients. Complications serious enough to cause those suffering such consequences of the virus, to have to be placed on breathing machines. As though that in itself is not worrying enough, a number of patients, some of whom tested positive for the virus were also experiencing paralysis or weakness in one of their limbs.

Such cases have popped up in the past week in hospitals located across Canada; in Toronto and Hamilton, Ontario, Edmonton and Calgary in Alberta, and Vancouver in British Columbia.  The virus, identified fifty years ago and generally considered insignificant, appears to have undergone some kind of alteration in its genetic makeup; if indeed it is responsible for these worrying polio-like symptoms.

Dr. Robinson noted that single-limb weakness in polio patients would on occasion spread to respiratory muscles; the end result making it difficult to breathe, and leaving affected patients to rely upon what was then called 'iron lungs' (mechanical medical breathing apparatus) to do the breathing for them. Although EV-D68 appears to be the culprit in these cases, it isn't quite certain whether the virus now represents a seriously dangerous new threat, or whether it's just another seasonal pathogen.

What adds to the confusion is that not all of the paralysis cases have ended up testing positive for the enterovirus. And when they do, it does not necessarily transcribe to the cause being EV-D68. Bugs ranging from West Nile to campylobacter, and even flu are capable of triggering similar symptoms, says Dr. Warshawsky. In fact a federal disease-surveillance program has documented 24 to 64 cases of "acute flaccid paralysis" occurring on an annual basis in children under 15, over the past 18 years.

About 100 different "serotypes" are classified as enteroviruses. Among them the rhinoviruses causing the common cold, and polio which once affected thousands of Canadians yearly, leaving many paralyzed or dead. But poliomyelitis was considered eradicated in Canada by 1994, thanks to two of the most famous vaccines ever developed, and formally declared no longer a threat to public health.

Discovered in 1962, Enterovirus D68 causes mild, cold-like symptoms in most people. Sporadic outbreaks over the years have previously not presented as cause for concern. Most disease labs had no reason to screen for it, so it is unknown whether it has been more prevalent than suggested by test results, explained Dr. Robinson. But it is no longer viewed as innocuous since it began showing up in greater numbers with a small proportion of children experiencing serious breathing problems.

British Columbia for example, has identified four patients with the virus suffering from limb paralysis or weakness, while Alberta health authorities are investigating cases in both Edmonton and Calgary. A hospital in Hamilton has four patients, one of whom tested positive for EV-D68, even while Sick Children's Hospital in Toronto tests three children with muscle weakness for the infection.

Four children suspected of enterovirus D68 in Alta
Four children with suspected enterovirus D68 being treated at Alberta Children's Hospital in Calgary are showing paralytic symptoms.

The Public Health Agency's surveillance system has recorded 24 instances of acute flaccid paralysis in children under 15 last year alone. None appears to have been triggered by polio; most the result of Guillaine-Barre syndrome, the body's immune system attacking the nervous system, causing partial or total paralysis, generally temporarily.

Cause and effect remain mysterious at the present time while diagnoses are ongoing, but it certainly does appear that nature has presented us with yet another serious viral threat impacting on public health, to be aware of.

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