As Ebola stokes media frenzy across the world, the Enterovirus that has been spreading its child-afflicting reach through the U.S. and Canada since late summer is receding into the background.
And that’s where the virus, known as EV D68, has typically dwelled since it was identified a half-century ago — as a pesky, sporadic, rite-of-passage pathogen in the population.
This year’s strain, however, seems particularly virulent. The first reported Canadian death came last week, when a young B.C. man in his 20s succumbed after contracting EV-D68. Ontario has had more than 160 confirmed cases.
It has been linked to seven deaths in the U.S., though none in Canada. It may also be linked to mild — and, likely, temporary — paralysis.
Related to hand-foot-and-mouth disease, EV-D68 belongs to a family of more than 100 respiratory viruses that have caused millions to sniffle, cough and ache for centuries.
“It’s also belongs in the same (viral) category as polio, but it’s not the same disease and doesn’t cause nearly the same complications,” says Bhagirath Singh, a microbiologist at Western University’s Schulich School of Medicine & Dentistry.
Indeed, the virus has ordinarily been so innocuous that it’s warranted little medical worry and even less research, notes Singh, who heads the London, Ont., school’s Centre for Human Immunology.
And that’s likely why there were no vaccines or antiviral medicines to combat it after its August onset in California, he says.
“It hasn’t really caused major problems (in the past). So there’s more cost-effective ways for companies to produce a vaccine than for something you may not have takers for.”
The U.S. Centers for Disease Control and Prevention reported this week that some 780 people — mostly children — stricken with severe respiratory ailments have tested positive for EV D68 since the summer.
In Canada, where hospitals are not obliged to report the virus to public health officials, it’s been harder to assess infection levels, says Dr. Upton Allen, head of infectious disease at Toronto’s Hospital for Sick Children.
“I don’t know that we are yet in a position to define the full burden in Canada,” Allen says. “I do know the public health agencies are putting numbers together to try to get a better feel.”
But any reported numbers almost certainly reflect a small fraction of those who have actually contracted the virus, Allen adds.
As with past appearances, most of the year’s EV D68 victims suffer simple cold or mild full symptoms and seek no medical care.
Sick Kids and most children’s hospitals across the country have seen sharp increases in the number of respiratory ailments they’ve treated over the past months.
“The good thing is that despite those higher volumes we . . . have been able to manage using our existing resources,” says Allen, who adds that things appear to be slowing down in the U.S. “At our centre as well, the early impressions are that things are starting to decline.”
This is a typical arc for the virus, which has tended to break out in geographic clusters every few autumns, flare up and quickly fade as winters arrived.
Its selective targeting of children is due largely to their lack of acquired immunity, Singh says. Since Enteroviruses as a class strike millions each year, most people have contracted several by the time they are out of their teens.
And each exposure to one variety of Enterovirus might create an immunity that could ward off or mitigate subsequent infections from any of them.
The EV D68 virus has been reported off and on to disease centers in the U.S. for decades, but in far smaller numbers than those logged this year.
Like any of its viral ilk, EV D68 can mutate and evolve with each outbreak. And this year’s strain, Singh says, has more virulence and potency than its predecessors.
Many of the children who have been critically stricken appear to have suffered from asthma and other reparatory conditions, says Dr. Stephen Wetmore, head of family medicine at Western.
Yet others, Singh says, might have genetic inabilities to fight it off.
Mild paralysis has been reported in dozens of children with the virus — a condition that’s unlikely to last, Singh says. “You may get a mild facial (paralysis) or (weak) hands for a few weeks or so but people usually recover.”
He adds what while it has been lined to Type 1 diabetes in the past, the virus’s relationship to both paralysis and diabetes is tentative and has been medically established.
Though the outbreak appears to by declining, parents should still be vigilant if their children develop flu-like symptoms, Allen says.
This is especially true if kids who appear to be recovering worsen again and develop new fever, breathing problems or muscle weakness.
But Wetmore warns that a greater yet far less ballyhooed viral threat — the annual influenza that kills tens of thousands across the continent each year — is in the offing.
And unlike EV D68, there are effective vaccines available each year to prevent influenza infection.
“These things like Ebola and Enterovirus D68 attract some media attention and create some concern among people,” Wetmore says. “And for reasons which I don’t really fully understand, a lot of people just regard influenza as being inconsequential when in fact, they should be much more concerned about that.”
This year’s flu shots, Wetmore notes, are being distributed now.