While we are currently focused on SARs-CoV-2, the virus that causes Covid-19, there is another virus that should especially be on the radar of parents of young children and teens.
The CDC recently published a report describing a specific virus that has been leading to outbreaks every 2 years since 2014, during the late summer and early Fall. The concern is that the virus is now likely to strike again during the next few months.
The virus is a member of the family of non-polio enteroviruses, and the reason we need to pay attention is that it has the potential to lead to permanent paralysis of muscles that control breathing and movement of arms and legs, a disease known as acute flaccid myelitis (AFM). Health experts have a high suspicion that a specific enterovirus, EV-D68, is the culprit leading to these dangerous outcomes.
That said, EV-D68 can lead to a wide spectrum of disease—from mild to severe respiratory illness or minimal to no symptoms at all. In fact, there are over 100 types of enteroviruses, and while most affect the gastrointestinal tract, EV-D68 has a preference for the respiratory tract. Symptoms may include a runny nose, cough, sneezing, along with body and muscle aches. Symptoms can progress to include wheezing and difficulty breathing.
It’s important to understand that EV-D68 may also lead to life-threatening respiratory diseases such as pneumonia in infants and children, particularly in those born premature or with chronic medical conditions.
While EV-D68 has also been implicated as one of the potential etiologies of AFM, the cause of most AFM cases is still unknown since the outbreak began in 2014. Based on data from the CDC, some cases have been linked to poliovirus (polio), non-polio enteroviruses and West Nile virus.
The increase in AFM cases we saw in 2014 occurred during a national outbreak of children with enterovirus D68 (EV-D68). However, the CDC did not consistently detect EV-D68 in every child with confirmed AFM. The data on the last cluster of reported cases of AFM in 2018 will have to be carefully evaluated to better understand the role of EV-D68 during this outbreak.
The ongoing concern is that we don’t have a way to determine which children may be at an elevated risk for developing AFM, or the underlying explanation that predisposes them to develop AFM in the first place. The search for a biomarker from the blood or cerebrospinal fluid is ongoing and would be helpful to identify those at elevated risk.
What’s also concerning, is that there is currently no approved treatment for AFM, other than supportive care that includes oxygen or ventilatory support if respiratory muscles are affected and breathing is compromised.
The long-term effects of AFM are unclear at this time. While some patients have recovered rapidly, others have remained paralyzed and require a high level of ongoing care to support their breathing and monitor for neurological deterioration.
Because the symptoms of AFM are quite similar to poliovirus, West Nile virus and adenoviruses, it’s very difficult to diagnose the condition. AFM may present with a sudden facial droop and difficulty keeping eyes open, slurred speech, and trouble swallowing. AFM can also affect the respiratory muscles, leading to difficulty breathing and the need for a ventilator in severe cases.
It’s important for parents to realize that at this time there is no specific treatment for AFM, and we can’t predict the clinical course of each child once diagnosed with the condition. Parents should also understand that while there have been an uptick in cases since 2014, the disease is still quite rare. AFM strikes less than one in a million persons in the U.S. annually.
That said, parents still need to remain vigilant for signs of muscular weakness or difficulty breathing that develop during and after recovery from an upper respiratory infection.
Enteroviruses are typically spread by either contact with secretions such as mucus, sputum or saliva from an infected person, but also by contact with feces. Enteroviruses are spread by direct contact, as well as by larger respiratory droplets. A person with enterovirus is contagious for about 10 days after symptoms develop.
As a result, it’s important to adhere to contact and droplet precautions precautions and take additional steps to reduce the risk of developing AFM by staying up to date on vaccinations, washing your hands thoroughly, and taking precautions to reduce the risk of mosquito bites.
AFM is a debilitating illness characterized by the sudden onset of flaccid limb weakness, with distinct grey matter lesions in the spinal cord on MRI. The site most often affected is the neck (cervical spine). While AFM is not a new condition, the large number of AFM cases reported since 2014–when the CDC first started surveillance for this condition—is a new and ongoing concern.
The prevailing thought is that AFM is most likely caused by a virus (EV-D68), as a result of similarities to poliovirus, associations with enterovirus D68, and its seasonal variation. Most patients experience a mild respiratory illness or fever consistent with a viral infection in the 1-2 weeks prior to onset of weakness. Onset of weakness is rapid—within hours to a few days—often asymmetric, along with potential involvement of cranial nerves. Progression to respiratory failure when it does occur is typically quite rapid.
Overall, it’s important to understand that MRI imaging within the first 3 days of limb weakness may be normal, and should be repeated if clinically indicated. Cerebrospinal fluid (CSF) sampling may reveal an elevated white blood count with a predominance of cells known as lymphocytes. Studies indicate that the chance of complete recovery in acute flaccid myelitis is rare.
Intravenous immunoglobulin (IVIG) (containing antibodies), corticosteroids, and plasmapheresis have been used to treat AFM, but there is not enough data regarding the efficacy of such approaches. Supportive care with fluids, oxygen, and medicine to treat fever are the mainstay of treatment at this time.
Up to 80% or more of children diagnosed with AFM have experienced ongoing limb weakness for many months after the onset of initial symptoms. Ongoing clinical experience indicates that aggressive rehabilitation and treatment in the early stages of the illness may help to improve outcomes.
Similar to the first two outbreaks, the average age of AFM patients in the 2018 outbreak was about 5 years of age. The majority had respiratory symptoms or fever in the first month of developing limb weakness.
A 2019 CDC report details severe symptoms noted in the 2018 cluster: 98% of patients required hospitalization, 60% needed care in the ICU, and 27% of patients were intubated. Multiple types of enterovirus and rhinovirus were noted in 44% of confirmed cases, mostly in respiratory and stool specimens. Enterovirus D68 (EV-D68) and enterovirus A71 (EV-A71) were the most common types of viruses noted.
In 74 cases in which a cerebral spinal fluid specimen was available, only two were found to be positive for enteroviruses— one patient with EV-A71, and one with EV-D68. No stool specimen tested positive for poliovirus, another related enterovirus that can cause AFM.
Since 2014, the CDC has tested spinal fluid of most patients with AFM. What’s important to know is that a pathogen been isolated and described in only a few cases.
As of July 31, 2020, according to CDC data, there have been 16 confirmed cases in 2020. There are also 38 patients under investigation (PUIs) for 2020. Other data indicates that 2 patients with confirmed AFM died in the acute phase of their illness—one in 2017 and other in 2020.
CDC data documented 46 confirmed cases of AFM in 2019 out of a total of 142 PUIs. CDC, state, and local health departments are still investigating some of the PUIs.
This far, there have been 633 confirmed cases since CDC began tracking AFM in August, 2014. The CDC has been thoroughly investigating cases since that time.
There has been an increase in AFM cases—predominantly in young children, every two years, since the CDC began tracking data in 2014. At this time, we don’t understand why the virus seems to skip a year.
That said, all medical providers and parents need to keep a high index of suspicion for AFM in young children with acute limb weakness, neck or back pain that develops after a upper respiratory infection in the late summer into early fall. We expect that AFM will likely have another peak in 2020. But, at this point it still not clear if or how Covid-19’s physical distancing recommendations and attention to mask wearing and hand hygiene will impact the degree of enterovirus we will end up seeing, along with new cases of AFM.
The same hygiene precautions for AFM also are applicable for the viruses that cause AFM. And the message to parents is that as some of the symptoms of Covid-19 may overlap with AFM, its best to be vigilant for any unusual symptoms of progressive weakness and difficulty breathing.
We also know that non-Covid-19 ER visits declined significantly in 2020 as a result of fear of contracting Covid-19. But the message to parents is not to delay care and a visit to the ER if their child has worrisome symptoms such as weakness or numbness of arms or legs, neck, back pain or difficulty breathing.
Fear about Covid-19 should not delay care and a trip to the ER, since time is critical and may be lifesaving.