Sunday, October 09, 2016

CDC Investigating Increase In AFM In The United States


Two weeks ago, in EID Journal Upsurge In EV-D68 In The Netherlands, 2016, I mentioned that the CDC was looking into an increase in the number of Acute Flaccid Myelitis (AFM) cases across the country over the past few months. 

Acute flaccid myelitis (AFM) is a rare illness that affects a person’s nervous system, specifically the spinal cord. AFM may be due to a variety of causes, including viral infection.

AFM is a subset of conditions that fall under a broader `umbrella' of syndromes called Acute Flaccid paralysis (AFP), which may include myelitis, peripheral neuropathy, myopathy, Guillain-BarrĂ© syndrome (GBS), toxic neuropathy, and other muscle disorders. 

In August of 2014 we saw a large increase in AFM cases tentatively linked to EV-D68, a relatively rare non-polio enterovirus that caused a nationwide outbreak of mild to moderate respiratory illness, mostly among children and teenagers. 

While no definitive causal link to EV-D68 has been established, a circumstantial case has been made over the past couple of years (see EID Journal  Enterovirus D68 Infection in Children with Acute Flaccid Myelitis, Colorado, USA, 2014).

There are, however, many other viruses - including EV-71, West Nile Virus, cytomegalovirus and Epstein-Barr virus, and adenoviruses - that can cause similar neurological symptoms

After reporting no EV-D68 cases in 2015, the CDC is reporting sporadic cases again this summer across the United States, as announced on the CDC's  About EV-D68 page.

What is happening with EV-D68 in 2016?

Updated July 2016

CDC is aware of limited sporadic EV-D68 detections in the U.S. in 2016. There is no indication of unusual activity. Enteroviruses are ever-present in the community, and each year we expect to detect cases. As in previous years, CDC will continue to work in 2016 with states by testing specimens to determine virus type, supporting the identification and investigation of outbreaks, and monitoring seasonal activity.

While a link to this increase in EV-D68 has not been established, the CDC has been monitoring an increase in AFM cases over the summer, which they update in the following report.

AFM in the United States

At a Glance

  • CDC is concerned about AFM, a serious illness that we do not know the cause of or how to prevent it.
  • CDC is investigating the increase in AFM in 2016. As of August 2016, 50 people in 24 states were confirmed to have AFM.
  • Even with an increase in cases in 2016, AFM remains a very rare disease (less than one in a million).
  • While the AFM case count for 2016 is less than the 2014 case count, CDC is concerned about the increase in cases in recent months.
  • CDC is intensifying efforts to understand the cause and risk factors of AFM.
  • It's always important to practice disease prevention steps, like washing your hands, staying up-to-date on vaccines, and protecting yourself from mosquito bites.

Acute flaccid myelitis (AFM) is a rare illness that anyone can get. It affects a person’s nervous system, specifically the spinal cord. AFM can result from a variety of causes, including viral infections.

Beginning in August 2014, CDC received an increase in reports of people across the United States with AFM for which no cause could be found. Since then, CDC has been actively investigating this illness. We continue to receive reports of sporadic cases of AFM. From January 1 to August 31, 2016, a total of 50 people in 24 states across the country were confirmed to have AFM.

What We Know

What we know about the AFM cases reported since August 2014:

  • The patients’ symptoms have been most similar to those caused by certain viruses, including poliovirus, non-polio enteroviruses, adenoviruses, and West Nile virus. See a list of viruses associated with AFM.
  • Enteroviruses can cause neurologic illness, including meningitis. However, more severe disease, such as encephalitis and AFM, is not common. Rather, they most commonly cause mild illness.
  • CDC has tested many different specimens from the patients for a wide range of pathogens (germs) that can cause AFM. To date, we have not consistently detected a pathogen (germ) in the patients’ spinal fluid; a pathogen detected in the spinal fluid would be good evidence to indicate the cause of AFM since this illness affects the spinal cord.
  • The increase in AFM cases in 2014 coincided with a national outbreak of severe respiratory illness among people caused by enterovirus D68 (EV-D68). Among the people with AFM, CDC did not consistently detect EV-D68 in the specimens collected from them. In 2015 there were no cases of EV-D68 detected and so far in 2016, only limited sporadic cases of EV-D68 have been detected in the United States.

What We Don't Know

What we don’t know about the AFM cases reported since August 2014:

  • Despite extensive testing, CDC does not yet know the cause of the AFM cases.
  • It is unclear what pathogen (germ) or immune response is causing the disruption of signals sent from the nervous system to the muscles causing weakness in the arms and legs.
  • CDC has not yet determined who is at higher risk for developing AFM, or the reasons why they may be at higher risk.

See Prevention for information about how to protect your family from viral infections that may cause AFM.

What CDC Is Doing

CDC is actively investigating the AFM cases and monitoring disease activity. We are working closely with healthcare providers and state and local health departments to increase awareness and reporting for AFM, and investigate the AFM cases, risk factors, and possible causes of this illness.

CDC activities include:

  • encouraging healthcare providers to be vigilant for AFM among their patients, and to report suspected cases to their health departments
  • verifying reports of suspected AFM cases submitted by health departments using a case definition adopted by the Council of State and Territorial Epidemiologists (CSTE)
  • testing specimens, including stool, blood, respiratory and cerebrospinal fluid, from people confirmed to have AFM
  • working with clinicians and state and local health departments to investigate and better understand the AFM cases, including potential causes and how often the illness occurs
  • providing new and updated information to clinicians, health departments, policymakers, the public, and partners in various formats, such as the Morbidity and Mortality Weekly Report, the AFM website, and CDC social media
  • pursuing an approach that uses multiple research methods to further explore the potential association of AFM with possible causes as well as risk factors for AFM. This includes collaborating with several medical institutions to review MRI scans of people from the past 10 years to determine how many AFM cases occurred before 2014.
For more information, see COCA Clinical Reminder (August 27, 2015) – Notice to Clinicians: Continued Vigilance Urged for Cases of Acute Flaccid Myelitis.
The 2014 investigation summary is available here: Acute Flaccid Myelitis in the United States—August – December 2014: Results of Nation-Wide Surveillance.

For more information on AFM surveillance, see the CSTE Standardized Case Definition for Acute Flaccid Myelitis.

For now the cause of this year's spike in AFM is unknown, but it is important to note that the numbers are still very small. Still, since AFM can often leave the patient with a permanent disability - and there is no specific treatment or cure - prevention is doubly important. 

Since AFM can be caused by a variety of viral infections - including those carried by mosquitoes - the CDC is urging people to take the following precautions:


Being up to date on all recommended vaccinations, including poliovirus, is one way to protect yourself and your family from a disease that can cause acute flaccid myelitis. Check with your doctor to make sure your family is up to date on all recommended vaccines.
You can protect yourself from mosquito-borne viruses such as West Nile virus—another known cause of acute flaccid myelitis— by using mosquito repellent and staying indoors at dusk and dawn, which is the prime period that mosquitoes bite. Removal of standing or stagnant water from nearby property to minimize the number of mosquitoes is also recommended.
You can help protect yourselves from other known causes of acute flaccid myelitis by—
  • washing your hands often with soap and water,
  • avoiding close contact with sick people, and
  • cleaning surfaces with a disinfectant, especially those that a sick person has touched.
Washing your hands the right way is one of the best things you and your children can do to protect against getting sick. Wash your hands
  • before you touch food;
  • after going to the bathroom, blowing your nose, changing a baby’s diaper, or touching an animal, an animal’s food, urine or feces; and
  • before and after taking care of a sick person or a cut or wound.

We'll undoubtedly come back to this story in the weeks ahead.  In the meantime, some related blogs from the past two years include:

Taiwan CDC: 1st Case Of EV-D68 With Acute Flaccid Paralysis 

ECDC: Rapid Risk Assessment On Recent Enterovirus Outbreaks In Europe

CIDRAP On The Lancet EV-D68 Analysis
Molecular evolution and the global reemergence of enterovirus D68 by genome-wide analysis

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