Enterovirus Infections Dwindle, But Mysteries Remain

The Ebola virus has dominated our conversations about health of late, but it has infected just eight Americans. Since August, enterovirus D68 has infected at least 1,112 American kids.

The virus continues to infect people in 47 states, but infections are slowing. Enterovirus activity tends to die down in the winter, and EV-D68 seems to be following the trend.

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Scientists have developed a faster test to identify EV-D68, which usually causes symptoms like those of a cold or flu, so numbers will likely rise before they fall off.

But there is “decidedly less disease occurring,” according to Dr. Mark Pallansch, director of the division of viral diseases at the Centers for Disease Control and Prevention (CDC).

Unanswered questions about this year’s flare-up of EV-D68 — a virus first identified in 1962 but one that hasn’t caused notable patterns of illness until recently — will take longer to dissipate.

A Few Deaths, Possible Paralysis

In the United States, at least one little boy died from the virus. New Jersey preschooler Eli Waller died in September. Canada recently confirmed that one young man with a history of asthma died from EV-D68 in British Columbia.

Nine deaths in which victims tested positive for the virus are under investigation, so the number of fatalities could rise slightly. 

Definitive answers on individual cases may never be made public. This is because the CDC identifies the virus in lab samples, but local authorities handle cause-of-death investigations and choose whether or not to make their findings public. Still, with numbers so low, it’s clear the virus kills only very rarely.

Perhaps the greatest mystery surrounding EV-D68 is whether it can, like its cousin poliovirus, sometimes cause paralysis.

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Doctors are looking into about 100 cases of unexplained paralysis, called acute flaccid myelitis, in young people, according to Dr. Emmanuelle Waubant, a neurologist at the University of California, San Francisco. Waubant, who was among the first doctors to suggest a possible connection between the two illnesses, attended a recent conference where neurologists came up with the rough count.

Many have publicly raised the question of whether these cases may stem from EV-D68. The CDC has remained mum on the possible connection, but the agency is looking into it behind the scenes.

“This is an open investigation because trying to rule in or rule out EV-D68 has not been simple,” said the CDC’s Pallansch.

“Enteroviruses as a group are extremely common and are responsible for a lot of respiratory disease,” he said. “The acute flaccid myelitis, whether it’s linked or not, is still an extremely rare condition, where the chance of having your child get this disease certainly seems to be less than one in 1 million.” 

The CDC has begun tracking cases of unexplained paralysis and developing treatment guidelines, an approach that Waubant called “reasonable.” 

“That’s a discussion we’ve had over and over with people in the infectious disease world,” she said.

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Same Time Next Year?

EV-D68 may well go away on its own. Experts aren’t even willing to venture a guess as to whether it will reassert itself again next summer.

“Having studied enteroviruses for the last 30 years, there’s no way that it’s possible to predict what’s going to happen in the following year,” said Pallansch. “All sorts of patterns are observed for these 100 different viruses. Sometimes they are indeed one-hit wonders: They’ll appear and then go away even for decades. Others are around every year at some reasonably low level and on occasion have a significant increase, so guessing what this one is going to do is something we’re definitely not going to do.”