Monday, February 24, 2014

Acute Flaccid Paralysis Cases In California



Credit CDC – Non Polio-Enteroviruses



# 8325


Overnight the news media has been filled with numerous reports of an – as yet, unidentified – polio-like paralytic illness that has stricken a small number of children in California over the past two years.  Crof already has a couple of media reports on his blog (see US: A polio-like illness in California children & US: More on the polio-like illness in California), and ProMed Mail released a summary this morning.


The basic facts are recounted in the following excerpt from the Los Angeles Times report, after which I’ll have more:


Mysterious polio-like illnesses reported in some California children

By Eryn Brown

February 23, 2014


The afflicted kids suffer severe weakness or paralysis, which strikes rapidly -- sometimes after a mild respiratory illness. Scans of the patients' spinal cords show patterns of damage similar to that found in polio sufferers, Glaser said. Two of the affected children tested positive for enterovirus-68, a virus that is usually associated with respiratory illness but which has been linked to polio-like illnesses as well.


Dr. Keith Van Haren, a pediatric neurologist at Stanford University's Lucile Packard Children's Hospital who has worked with Glaser's team, will present the cases of five of the children at the American Academy of Neurology's upcoming annual meeting in Philadelphia.


All five patients had paralysis in one or more arms or legs that reached its full severity within two days, he said. None had recovered limb function after six months.


"We know definitively that it isn't polio," Van Haren added, noting that all had been vaccinated against that disease.

(Continue . . . )


This report, along with others, suggest that 20 to 25 children in California may have developed Acute Flaccid Paralysis (AFP) following a mild respiratory illness over the past couple of years, and investigators expect that once clinicians know to look for it, they may discover it beyond California.


Non-polio AFP is a complex and broad clinical syndrome that can be caused by a wide range of pathogens, including West Nile Virus (and other mosquito-borne encephalopathies), echoviruses, adenoviruses, Campylobacter jejuni (leading cause of Guillain-Barre syndrome), a large group of enteroviruses, along with a variety of toxins and poisons.


While the exact cause (or causes) of these California cases remains unknown, a viral infection is strongly suspected, and high on the list of suspects are members of the ubiquitous non-polio enterovirus family of viruses or NPEVs  (which includes Coxsackievirus A, Coxsackievirus B, Echoviruses & numerous other Enteroviruses).


According to the CDC, NPEVs cause 10 to 15 million – mostly mild and often asymptomatic – infections in the United States each year, primarily among infants, children, and teenagers. Fever, runny nose, sneezing, coughing, a skin rash or mouth blisters, and body and muscle aches are the most commonly reported symptoms


NPEV infection may also lead to viral conjunctivitis, hand, foot, and mouth disease (HFMD), or viral meningitis and less commonly, a person may develop myocarditis, pericarditis, encephalitis - or in rare cases - even paralysis.


The CDC lists the following common Outbreaks of Various Non-Polio Enteroviruses

    • Coxsackievirus A16 is the most common cause of hand, foot, and mouth disease (HFMD) in the United States. However, in 2011 and 2012, coxsackievirus A6 was a common cause of HFMD in this country; some of the infected people became severely ill.
    • Coxsackievirus A24 and enterovirus 70 have been associated with outbreaks of conjunctivitis.
    • Echoviruses 13, 18, and 30 have caused outbreaks of viral meningitis in the United States.
    • Enterovirus 71 has caused large outbreaks of HFMD worldwide, especially in children in Asia. Some infections from this virus have been associated with severe neurologic disease, such as brainstem encephalitis.


We’ve looked at HFMD outbreaks in the past, most often caused by the Coxsackie A16 virus (and more rarely by Coxsackie A10) here in the United States. In recent years, we’ve also seen the recent emergence of the Coxsackie A6 virus which has been linked to somewhat more severe HFMD cases (see MMWR: Coxsackievirus A6 Notes From The Field).

But it is the Enterovirus 71 that has been most often linked to severe cases of HFMD – particularly across Asia - with serious outbreaks recorded over the past 15 years in places like China, Taiwan, Malaysia, Hong Kong, and two years ago in both Vietnam and Cambodia (see Updating The Cambodian EV71 Story).


Last year, in Australia: Acute Flaccid Paralysis & EV71, we looked at a report from the National Enterovirus Reference Laboratory in Australia that described 5 recent cases of acute flaccid paralysis (AFP) in children who tested positive for the EV71 virus.


Concerns over the evolution and spread of EV71 have grown in recent years, as detailed in the following 2008 report from The Lancet: Enterovirus 71 infection: a new threat to global public health?  


While a potential cause, EV71 is just one of the possible suspects behind these California cases.  Indeed, AFP can be caused by a variety of viral infections, and so there may be more than one etiology involved


At least two of the children in California have tested positive for Enterovirus-68, which we looked at in some depth back in 2011 (see MMWR: Clusters Of HEV68 Respiratory Infections 2008-2010).  First detected in California in 1962, but rarely seen since that time, that report summarized six clusters of HEV68 from Asia, Europe, and the United States between 2008-2010.  Those clusters included severe illness, and three fatalities.


Although the full spectrum of illness that EV-68 infection can produce has not been well established, it has previously been more commonly associated with respiratory symptoms than with paralysis.


So whether EV-68 is actually the cause of these recent California paralysis cases, or simply an incidental finding, is something that will require more research to establish. Despite their outward similarity to NPEV infections, these AFP cases in California may be due to something altogether different.  New viral discoveries are made practically every year.

But most `mystery illnesses’  usually end up being due to previously identified diseases that have either evolved or mutated a bit, or have migrated to a new area.


While it is too soon to speculate on the exact cause of these AFP cases, the CDC’s recommendations to prevent NPEV transmission are universally good hygiene suggestions, and are worth following:


You can help protect yourself and others from non-polio enterovirus infections by—

  • Washing your hands often with soap and water, especially after using the toilet and changing diapers,
  • Avoiding close contact, such as touching and shaking hands, with people who are sick, and
  • Cleaning and disinfecting frequently touched surfaces.