EV-71 confirmed as cause of Cambodian outbreak

  • July 13, 2012

Health officials have confirmed that the illnesses and deaths among children in Cambodia were a result of a severe form of hand, foot and mouth disease caused by enterovirus 71, according to the World Health Organization.

A disease outbreak ongoing since April that has resulted in more than 78 illnesses and 54 deaths among children in 14 Cambodian provinces. Laboratory samples were unavailable for most of the patients because they died before appropriate samples could be taken. Of the 31 samples available, most tested positive for enterovirus 71 (EV-71), a known cause of hand, foot and mouth disease (HFMD). However, some of the patients also tested positive for other pathogens, including dengue and Streptococcus suis. None of the samples tested positive for any type of influenza, SARS or Nipah.

The 78 cases were identified from several hospitals, but the investigation focused on 61 cases that met the specific case definition. Most of the children were aged younger than 3 years and some of the children suffered from chronic conditions. A significant number of cases were treated with steroids at some point during their illness, which has been shown to have adverse effects on patients with EV-71.

The Ministry of Health has requested that health centers report all patients with HFMD, and enhanced surveillance in now in place for neurorespiratory syndrome, a key syndrome observed among patients with severe HFMD caused by EV-71. Occasional new cases are expected in the coming months as a result of the enhanced surveillance, according to WHO.

Perspective
James Hughes

James M. Hughes

  • An outbreak of severe unexplained illness in children with a high mortality rate is being investigated in Cambodia. Infectious agents and toxins come to mind as possible explanations. Much more clinical, epidemiologic, and laboratory information is needed, but preliminary laboratory results suggest that the illness may be hand, foot, and mouth disease caused by enterovirus 71. This virus has caused several large outbreaks of severe illness among children in Southeast Asia in recent years. This outbreak highlights the importance of disease surveillance, diagnostic laboratory capacity, and timely dissemination of public health information as emphasized by the International Health Regulations (IHR 2005). As the investigation involving national and international health agencies continues, it is important to maintain an open mind regarding the diagnosis until more definitive clinical and epidemiologic information and laboratory results are available.

    • James M. Hughes, MD
    • Professor of Medicine and Public Health
      Emory University
      Infectious Disease News Editorial Board member
  • Disclosures: Dr. Hughes reports no relevant financial disclosures.
Perspective

José R. Romero

  • Enterovirus 71 (EV-A71) is a small, non-enveloped RNA virus in the genus Enterovirus of the Picornaviriae family of viruses. Members of the genus Enterovirus are primarily transmitted via the fecal-oral route, although studies have suggested the EV-A71 may be primarily transmitted via the respiratory route though large droplets from the oral cavity. The virus can be also found in the stool and vesicular fluid of infected individuals. The majority of EV infections occur in the summer to early fall. Prolonged shedding of the EVs favor their spread among a susceptible population and asymptomatic infection is common in EV infections.

    Phylogenetically, EV-A71 is most closely related to Coxsackievirus A16 (CV-A16) and, as with CV-A16, it can cause hand, foot and mouth disease (HFMD). EV-A71 has been associated with neurologic syndromes including aseptic meningitis, acute flaccid paralysis and a brain stem encephalitis (rhombencephalitis). The latter can be fatal when it results in neurogenic pulmonary edema. 

    Outbreaks of EV-A71 associated with severe neurologic disease have been reported worldwide and primarily in the Asia-Pacific region. The largest of these occurred in 1998 in Taiwan and was associated with thousands of cases of HFMD, more than 400 cases of central nervous system (CNS) disease and 78 deaths in children. In the United States, EV-A71 has been associated with sporadic cases of CNS disease. 

    Physicians should suspect EV-A71 (and CV-A16) infection in children with aseptic meningitis, acute flaccid paralysis or encephalitis immediately preceded by HFMD. The virus should be sought in throat secretions, stool, vesicular fluid and cerebrospinal fluid (CSF). Nucleic acid amplification testes may be particularly useful in detecting EV in CSF. However, current nuclear acid amplification tests used for detection of the EV cannot differentiate the individual serotypes. Management of CNS syndromes is symptomatic, as no specific therapy exists. No vaccine is currently available. Prevention of infection may be aided by good hand hygiene and avoidance of contact with respiratory secretions from infected individuals.

    • José R. Romero, MD
    • Infectious Diseases in Children Editorial Board
  • Disclosures: Dr. Romero reports no relevant financial disclosures.

Comments

Healio is intended for health care provider use and all comments will be posted at the discretion of the editors. We reserve the right not to post any comments with unsolicited information about medical devices or other products. At no time will Healio be used for medical advice to patients.