Tuesday, July 10, 2012

EV71: Cambodia’s Prime Suspect


Photo Credit University of Iowa


# 6427



Although normally a mild childhood disease, HFMD (Hand, Foot, & Mouth Disease) has taken center stage in the media these past few days as one of the viruses (EV71) associated with that illness has been tentatively linked to dozens of deaths of Cambodian children over the past three months.


The epidemiological investigation is ongoing, with researchers looking for any possible complicating factors (or changes to the virus) that might explain the unusually high mortality rate being reported with this outbreak. 


We should know more in a few days, but as you’ll see, the EV71 virus doesn’t need any help to be deadly. 


HFMD can be caused by a variety of viruses, and most of the time, it is mild and only rarely requires medical attention.


The most common cause of the illness is the Coxsackie A16 virus, and more rarely the Coxsackie A10 virus. In recent years, we’ve also seen the 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 Enterovirus 71 that has been linked to the most severe cases of HFMD – particularly across Asia - with serious outbreaks recorded over the past dozen years in places like China, Taiwan, Malaysia, Hong Kong and most recently, Vietnam.


In addition to the classic HFMD symptoms, this virus has been known to produce serious neurological illness, including life threatening encephalitis. 


You can find more details on HFMD, and EV71, in the World Health Organization’s Hand, Foot and Mouth Disease Information Sheet, from which I’ve excerpted the following:


  • HFMD is usually a mild disease, and nearly all patients recover in 7 to 10 days without medical treatment and complications are uncommon.
    • Dehydration is the most common complication of HFMD infection caused by coxsackieviruses; it can occur if intake of liquids is limited due to painful sores in the mouth.
    • Rarely, patients develop "aseptic" or viral meningitis, in which the person has fever, headache, stiff neck, or back pain, and may need to be hospitalized for a few days.
  • HFMD caused by EV71 has been associated with meningitis and encephalitis, and on occasion can cause severe complications, including neurological, cardiovascular and respiratory problems. Cases of fatal EV71 encephalitis have occurred during outbreaks.


While the recent outbreak in Cambodia has raised alarms around the world, deadly outbreaks of EV71 are nothing new.  Last May, in CDC Issues HFMD Travel Notice For Vietnam, we looked at an outbreak that had claimed more than 20 lives.


In the News
Hand, Foot, and Mouth Disease in Vietnam

Released: May 25, 2012

What Is the Current Situation?

As of April 29, 2012, the Vietnam Ministry of Health has confirmed nearly 40,000 cases of hand, foot, and mouth disease (HFMD) since the beginning of 2012. Cases have occurred in 63 provinces, and 20 deaths (all in children under 5) have occurred in 10 provinces.

(Continue . . .)


The CDC also provides several  multimedia products related to hand, foot, and mouth disease.



Similarly, we’ve seen reports this week indicating that Hand, foot, mouth disease kills 240 in China.


We are seeing reaction to the Cambodian outbreak from several health departments across Asia, including Hong Kong, Thailand, and the Philippines.


First, Hong Kong’s CHP (Centre for Health Protection) which sent out this Update on An Unknown Disease in Cambodia letter to doctors in the region on July 9th, which asks that doctors notify the CHP of any suspected cases with recent travel history to Cambodia.


Possibly related, the CHP is reporting on Two cases of severe paediatric enterovirus infection, although the causative virus is not indentified.


In Thailand, The Nation newspaper is reporting that the MOH has instructed schools to close if an unusual number of HFMD cases are reported.


Disease warning for schools

The Nation July 10, 2012 5:47 pm

The Public Health Ministry on Tuesday instructed schools and nurseries nationwide to close if they find that students in five classes or more have contracted hand, foot and mouth disease.

(Continue . . . )


And perhaps the most proactive of all is the Philippines, where the Department of Health has ordered increased surveillance at airports, and has declared  EV-71 to be a notifiable disease. 


Here is the official press release:



July 10, 2012

(Press Release – 10 July 2012)

Health Secretary Enrique T. Ona instructed today the Department of Health (DOH) National Epidemiology Center to include Enterovirus-71 (EV-71) infection as a notifiable disease in the country. This will compel all health providers especially physicians to report individual cases or even outbreaks.


“Mandatory notification will improve monitoring of EV-71 infections and ensure that necessary measures are in place to guarantee that the Philippines is free from the highly fatal severe form of EV-71 infections that have claimed the lives of at least 60 children in Cambodia since April this year,” Ona said.


Also, the DOH and the World Health Organization (WHO) clarified today that the Cambodian EV-71 was of the encephalitis type and not hand foot and mouth disease (HFMD) as earlier reported. Affected Cambodian children generally presented with fever followed by rapid respiratory deterioration and impaired consciousness. Death occurred 24 hours from hospital confinement.


EV-71 causes different diseases of varying intensity. These include the often mild hand, foot and mouth disease (HFMD), acute respiratory disease, acute flaccid paralysis (polio-like) and the deadly brainstem encephalitis. HFMD is characterized as a self-limiting illness presenting with fever and accompanied by skin lesions or rashes.


EV-71 infections do occur in the country but are reported with irregularity. Fatal EV-71 infection is still very rare in the Philippines.


Proper disposal of baby diapers or human waste, strict personal hygiene and regular hand washing prevent viral spread. The virus is known to be excreted in the feces since it is found in human intestines.



The DOH urges parents and day-care personnel to clean and disinfect toys and teaching tools that are easily shared with other children. This can prevent EV-71 infections, as there are no known effective drugs or vaccines.



‘There is still no travel restriction to and from Cambodia and incoming passengers will be subjected to thermal screening upon arrival in all international airports as a routine quarantine procedure,” the health chief concluded.


The statement above, that the `(WHO) clarified today that the Cambodian EV-71 was of the encephalitis type and not hand foot and mouth disease (HFMD)’ is something I’ve not been able to locate on the WHO site yet.  


And last, but certainly not least, Lisa Schnirring of CIDRAP NEWS wrote a detailed report last night on the Cambodian outbreak, which you can read at:


Enterovirus 71 cited in puzzling Cambodian infections

Lisa Schnirring * Staff Writer

Jul 9, 2012 (CIDRAP New) – Lab analysis in the mysterious recent illnesses and deaths of dozens of Cambodian children pointed to enterovirus 71 (EV-71), a virus that causes hand, foot, and mouth disease (HFMD) and can lead to severe complications in some patients, the World Health Organization (WHO) announced today.

(Continue . . .)



The peak season for HFMD is summer and fall, which suggests that we will be hearing about outbreaks of EV71, and other HFMD viruses, for months to come.