Enteroviruses are a genus in the Picornaviridae, a large family of related RNA viruses that includes polioviruses (which are not discussed here). Non-polio enteroviruses associated with human infection include a range of coxsackieviruses, echoviruses and numbered enteroviruses. Parechoviruses represent a closely related but separate genus within the same family, some of which also affect humans.
Enteroviruses and human parechoviruses are primarily spread by contact with the faeces or respiratory secretions of infected people. Hand hygiene particularly after toileting or nappy changes is an important measure to control the spread of infection.
While more than 90% of enterovirus and human parechovirus infections are asymptomatic or result in a non-specific febrile illness, some strains are associated with a greater risk of complications, particularly in young children.
EV71 is one of a number of non-polio enteroviruses associated with an increased likelihood of neurological complications. This strain has caused several outbreaks in NSW in recent years, with affected children presenting with an acute febrile illness and neurological complications including meningitis, encephalitis, and acute flaccid paralysis. This can be sometimes followed by rapidly progressive, and potentially fatal, cardio-respiratory collapse due to neurogenic pulmonary oedema.
During EV71 outbreaks people are predominantly affected with mild forms of disease, such as hand, foot and mouth disease (HFMD), but in a small number of cases neurological disease can occur.
Children under 5 years of age, particularly those under 2 years, are most likely to develop severe disease. Hand, foot and mouth disease (HFMD), or a history of contact with a case of HFMD, are occasional but not consistent findings in these children.
Signs of complicated EV71 infections include the following:
HPeV was detected in a number of neonates and young infants admitted to NSW hospitals in spring/summer 2013 and again in 2015. Infants presented very unwell with a rapid onset of acute sepsis-like symptoms. This was often followed by an erythematous, often confluent rash. There were also a number of cases involving abdominal complications such as volvulus, intussusception and bowel ischemia.
Children under 3 months of age are most likely to develop severe disease, but older infants may also be at risk. Most recover with supportive treatment.
Signs of complicated HPeV infections in neonates or young infants with sepsis-like illness and fever >38°C include the following:
EV-D68 is known to cause mild to severe respiratory illness, ranging from fever, rhinorrhoea, cough and myalgia, to wheezing and difficulty breathing resulting in hospital admission. It has also been associated with cases and clusters of polio-like neurological symptoms, including paralysis and meningo-encephalitis.
Although EV-D68 has only rarely been detected in Australia, there has been increased reporting of cases overseas in recent years, including many case reports from the USA and Canada during 2014. The US CDC reported additional cases in 2016. Infants, children, and teenagers are believed to be more likely to have symptomatic infections and complications. Children with asthma may have a higher risk for severe respiratory illness caused by EV-D68 infection.
EV-D68 should be considered as a possible cause of disease in patients with severe unexplained acute respiratory infection and/or with unexplained neurological symptoms, when:
In particular, EV-D68 should be suspected for clusters of severe acute respiratory disease, or unexplained neurological symptoms.
Infants presenting to NSW hospitals with a fever, sepsis-like signs and/or neurological signs, including excessive irritability, should be assessed and treated for suspected sepsis using local protocols and discussed with an Emergency Consultant or Paediatrician. Cases presenting outside of a hospital setting should be immediately transferred to an Emergency Department for assessment.
Collect a stool specimen (or viral rectal swab) and throat swab or NPA for enterovirus PCR. A stool specimen is preferable to a rectal swab.
Referral for specialist Paediatrician review is recommended after recovery from the acute illness in cases of infant parechovirus or severe enterovirus infection for assessment and advice regarding on-going management and follow-up.
Enteroviruses and parechoviruses are spread from person to person by contact with respiratory secretions or faeces of infected people.
Standard precautions should be supplemented with contact and droplet precautions, and hand hygiene re-enforced.
Consult with infectious disease clinicians at the Children’s Hospital Westmead (02 9845 0000 pager 6675) or Sydney Children’s Hospital (02 9382 2222 pager 44893 or via the switchboard).