Do we really know whether or not acute flaccid myelitis is contagious or not?
Many people were surprised by a comment by Dr. Robert Redfield, the director of the Centers for Disease Control and Prevention, in an interview for “CBS This Morning,” during which he said that acute flaccid myelitis:
“doesn’t appear to be transmissible from human to human.”
Wait, then how do kids get it?
Is Acute Flaccid Myelitis Contagious?
Since we don’t actually know what causes AFM, it is certainly possible, although rather unlikely, that it is caused by something that is not communicable.
But remember, the leading theory is that AFM is caused by an enteroviral infection, either EV-D68 and EV-A71, as most kids develop symptoms shortly after they had viral symptoms, and these two viruses are most commonly identified.
And you are typically contagious when you are sick with an enteroviral infection.
So how can the CDC Director say that AFM “doesn’t appear to be transmissible from human to human?”
It is because even if the virus that causes AFM is communicable, you can’t actually catch AFM from someone.
Just like polio.
While the polio virus itself is communicable, paralytic polio isn’t. You can’t catch paralytic polio. Instead, you can catch polio, and then you have the small chance that it develops into paralytic polio.
It may not sound like a big difference, but it is.
Just consider what might happen if AFM itself was contagious, and if most of the kids who were exposed to someone with AFM developed AFM themselves…
We would likely see a lot more cases of AFM, especially in clusters in homes, daycare centers, and schools.
Instead, most cases seem to be isolated.
But aren’t there reports of clusters of AFM?
“In September 2016, an acute care hospital in Arizona notified the Maricopa County Department of Public Health (MCDPH) of a suspected case of AFM and subsequent cluster of 11 children who were evaluated with similar neurologic deficits; differential diagnoses included transverse myelitis and AFM.”
Notes from the Field: Cluster of Acute Flaccid Myelitis in Five Pediatric Patients — Maricopa County, Arizona, 2016
Yes, kind of.
But they aren’t clusters of epidemiological linked cases.
In Arizona, for example, only four of the 11 children were confirmed to have AFM and “no epidemiologic links were detected among the four patients.”
“In October 2016, Seattle Children’s Hospital notified the Washington State Department of Health (DOH) and CDC of a cluster of acute onset of limb weakness in children aged ≤14 years.”
Acute Flaccid Myelitis Among Children — Washington, September–November 2016
Similarly, at Seattle Children’s Hospital, the ten cases in their “cluster” had nothing in common, except for having prodromal respiratory or gastrointestinal symptoms about seven days before developing AFM symptoms.
It is likely that you see “clusters” at some hospitals simply because they are referral hospitals for a large region.
But even if we don’t know why some kids with these viral infections develop paralysis and other don’t, if they are the cause, then you wouldn’t develop AFM if you never actually had the virus.
“While we don’t know if it is effective in preventing AFM, washing your hands often with soap and water is one of the best ways to avoid getting sick and spreading germs to other people.”
About Acute Flaccid Myelitis
So handwashing and avoiding others who are sick is still the best strategy to try and avoid getting AFM.
While acute flaccid myelitis is certainly mysterious, that doesn’t mean that we don’t know a lot about it already.
Most people are aware that there is a so-called “mystery illness” going around.
A “mystery illness” that is paralyzing some kids.
What’s so mysterious about it?
What is Acute Flaccid Myelitis?
Lots of things are mysterious about acute flaccid myelitis…
We don’t know exactly what causes it, who will get it, why they get it, or how to treat it, etc.
What do we know?
AFM is not new, although we are seeing more cases lately
AFM refers to acute (sudden onset) flaccid (droopy or loose muscles) myelitis (inflammation of the spinal cord) and it is a subtype of acute flaccid paralysis
most cases occur in children, with the ages of affected children ranging from 5 months to 20 years, although some adults have been affected
these children have a magnetic resonance image (MRI) showing a spinal cord lesion largely restricted to gray matter and spanning one or more vertebral segments
it is thought that AFM can be caused by viruses (polio, non-polio enteroviruses, West Nile virus, Japanese encephalitis virus, CMV, EBV, adenovirus, etc., environmental toxins, and genetic disorders, and although no common etiology has been found in these recent cases, most experts think that these cases are caused by a neuroinvasive infectious process, likely of viral etiology, including EV-D68 and EV-A71.
these cases of AFM are not thought to have a post-infectious immune-mediated etiology
cases are occurring sporadically – after 120 cases in 34 states in 2014, there were only 24 cases in 17 states in 2015, but then 149 cases in 39 states in 2016 and 33 cases in 16 states in 2017. And there have been at least 158 cases in 36 states in 2018, with another 153 cases under investigation.
outbreaks of EV-D68 and sporadic cases of AFM have also been seen in other countries recently, including Denmark, France, the Netherlands, Spain, Sweden and the United Kingdom (UK)
most cases occur in the late summer and early fall
most had symptoms of a preceding viral illness, including respiratory symptoms or diarrhea
EV-D68 is not new, being first discovered in California in 1962
While that’s a lot of good information, for parents wanting to protect their kids and avoid AFM, there is some key information missing. Same for those wanting to help treat their kids who have or have had AFM.
So although some folks don’t like that it is being called a “mystery illness,” there is still a lot of mystery to it.
But that doesn’t mean that experts aren’t working very hard to take all of the mystery out of AFM.
What Causes Acute Flaccid Myelitis?
Some experts are fairly sure that AFM is caused by an enteroviral infection, to the point that they hope that the CDC focuses work on an enteroviral vaccine.
Which enterovirus though?
At least two different enteroviral infections have been associated with AFM, including EV-D68 and EV-A71.
You would first have to make a individual vaccines, before thinking about combining them, and you can’t just make any vaccine you want. If you could, we would have vaccines to protect us against RSV, malaria, HIV, and many other diseases.
Still, since EV-A71 also causes serious outbreaks of hand, foot, and mouth disease in some parts of the world, a vaccine has actually been in development for some time, and two are approved for use in China. That at least means making an EV-A71 vaccine is possible, although we would likely need to make our own.
Why did they make a vaccine for a virus that causes hand, foot, and mouth disease (HFMD)? Because unlike the HFMD that we are used to, which is typically caused by coxsackievirus A16 virus, another enterovirus, when caused by EV-A71, it can be deadly, as we have seen in outbreaks in Asia.
What about an EV-D68 vaccine?
While likely possible, since developing a new vaccine takes a lot of time, we want to be sure that is what is causing the outbreaks.
Do some kids not have either EV-D68 or EV-A71 because it just isn’t detected or because something else is causing them to have AFM? Possibly. One of the biggest issues that is troubling some experts though is that they have not detected these enteroviruses in the spinal cord fluid of many children, as you would expect if the viruses were causing the damage.
But even if these enteroviral infections are the cause, are there other risk factors that make some kids who get these enteroviral infections more predisposed to develop AFM, instead of more typical viral symptoms, like a cold or diarrhea?
And why are we seeing cases now? Did the virus, if that is the cause, just mutate into one that is more virulent?
Hopefully we get some more answers and a way to prevent, treat or cure AFM soon.
Until then, we can make sure we take steps to prevent the known causes of AFM, including polio (get vaccinated) and West Nile virus (use insect repellent), and wash hands properly to help avoid all other viral infections. You also want to get your flu vaccine! The flu can cause Guillain-Barré syndrome, which can also cause AFM.
“…is there any relationship between vaccination status and a developing acute flaccid myelitis? Meaning, are vaccines a risk factor? And the data so far says no, the overwhelming number of children who have gotten AFM have had no recent vaccination of any kind or vaccine exposure. These cases over these years have been happening before flu season and flu vaccination starts, which is one of the questions that comes up, and there hasn’t been any pattern to vaccine exposure of any kind in developing AFM. So far, we have not found a link between the two.”
Benjamin Greenberg, MD on 2018 Podcast on Acute Flaccid Myelitis
While it might be scary to think that there is a new condition out there that we don’t know everything about, parents should be reassured that experts are actively seeking the cause and a way to both prevent and treat AFM.