Dr. Marc Siegel: Mystery muscle-weakening disease is sparking panic among parents – here's what you must know

Parents everywhere are concerned about continuing news reports dealing with a mysterious muscle-weakening condition that few people had ever heard of until a few weeks ago – acute flaccid myelitis, abbreviated as AFM. 

It’s important to understand that fewer than one or two in a million U.S. children get AFM. It’s also important to understand that this serious condition is not itself contagious – so you won’t get AFM by being in contact with someone who has it.

Yet fear of the disease – like fear of many other diseases – is contagious and almost impossible to control. This is a phenomenon I discussed in my book “False Alarm: The Truth about the Epidemic of Fear.”

AFM is frequently accompanied by a horrifying scenario. A young child is playing, perhaps feels a cold or fever coming on, and then suddenly develops facial weakness or problems with speech, swallowing, and weakness in his or her arms or legs.

It’s no wonder that parents everywhere are connecting to the panic and feeling of powerlessness that ensues. We are our children’s protectors – but AFM strikes without warning and we are helpless to protect them.

Some 90 percent of AFM cases that have occurred this year are in children younger than 18. No virus or any other cause of this terrible illness has yet been identified in this year’s outbreak.

I can’t emphasize enough how rare this condition is. The U.S. Centers for Disease Control says that this year only 62 cases of AFM have been reported in the U.S. in a total of 22 states as of Friday. There have been an additional 93 possible cases.

In fact, from 2014 through September this year only 386 cases of AFM have been found in the U.S., which has a total population of nearly 329 million.

So the usual advice to protect yourself from infection – such as “wash your hands,” or “try to avoid getting mosquito bites” – seems absurdly ineffective and pointless. In fact, this advice helps spread fear by making the risk of getting AFM seem far greater than it actually is.

Panic is wildly irrational – though understandable – when a condition is so rare and the numbers so low.

Unfortunately, on the rare occasions when AFM strikes, no parent can ever be properly prepared.

And even more unfortunately, no amount of physical therapy can make the symptoms of AFM disappear – though sufferers can vastly improve over time with proper therapy.

The Centers for Disease Control has been tracking AFM and is trying to figure out why it has been striking at a higher rate since 2014.

In 2014 the CDC confirmed 129 AFM cases in the U.S. There were only 17 cases in 2015, another 149 in 2016, and 33 in 2017. Though the final tally of confirmed cases for 2018 isn’t yet determined, it looks like it may be the highest number of annual cases yet.

The diagnosis of AFM is made when doctors find a loss of muscle strength accompanied by diminished reflexes, along with a spinal cord lesion confirmed by MRI.

Past causes of AFM include West Nile virus (usually spread to people by mosquito bites); environmental toxins; vaccinations; and polio – a disease with similar manifestations to AFM.

However, Mark Pallansch, director of the division of viral diseases at CDC, told me in an interview last week that there is absolutely no evidence that these are possible causes of the current outbreak.

A more likely cause of AFM is a strain of a common respiratory non-polio enterovirus that can rarely cause neurological problems. There are more than 100 of these non-polio enteroviruses. One that has been associated with AFM in the past is called EV-D68.

Pallansch told me that medical researchers have not yet been able to find direct evidence of the presence of this type of virus in people with AFM this year. However, he said it is possible that by the time the symptoms of AFM occur the virus itself is no longer easily measured.

EV-D68 has been increasing in the U.S. The most common season for onset of AFM is fall, and back in 2014 the AFM outbreak correlated with a national outbreak of respiratory illness due to EV-D68.

At least one recent study has suggested EV-D68 as a possible cause of AFM. If the strain of virus is ever identified and confirmed as a cause of AFM, a vaccine might be possible, though it would be very expensive to produce.

Of course, it is impossible to put a price tag on protecting children from a microbe that suddenly takes away their strength and independence before they’ve ever had a chance to develop their full potential. That’s why it’s so important that research continue on AFM.