Enterovirus A to D

The A to D of enterovirus species in WA: from enterovirus 71 to echovirus 4. David Williams & Simon Williams.  

Democritus

The enteroviruses (CDC post):

  • A coxsackie, HFMD 
  • B echovirus, cardiac complications 
  • C poliovirus 
  • D enterovirus 68, 70

7.5kb genome with one large ORF, encoding one large polyprotein, broken down after incorporation into cell, including structural components of the virus capsid.

Picornavirus, small and RNA virus. Capsid covered in pentameric units, including poliovirus receptor.

HFMD best known. Transmission by direct or indirect contact. Child care centres are hot spots. Common exanthema of young children. Fever, vesicular rash on foot, hands & in mouth. All groups associated with HFMD including enterovirus 71.Big epidemics in SE Asia.

Herpangina and neurological disease. Fever & sore throat, popular lesions at back of mouth. Severe neurological disease can develop. Enterovirus 71 can cause septic meningitis, acute flaccid paralysis, cerebellar or brain stem encephalitis and can cause epidemic spread (outbreaks). 1999 outbreak in WA. Perth, 6,000 cases of HFMD, 29 cases of CNS disease, no deaths. Taiwan 1998. 130,000 cases, 405 CNS and 78 deaths.

Enterovirus 71. Became extinct. B and C – 5 subgenogroups each. Now most important neurovirulent enterovirus in SE Asia. No effective vaccine for this virus. Public health surveillance programmes are main effort, APNET & VIDRL.

Diagnostic support. Rt-PCR. 5UTR region. Hypia & Ireland. Sequence can type reliably but not subtype. Other targets needed for subtyping. VP1 and VP3 targets by consensus degenerate hybrid oligonucleotide primers (codehop). ENV71 detection by rt-PCR as duplex for B and C.

ENV71 and CAV6 are most common enteroviruses in WA recently. Peak HFMD in WA this winter.CAV6. Current strains fairly close to Finnish strain 2008.

Echo 4 variant. Epidemic febrile vomiting, some cases of meningitis in NT from July 2007 onwards. Sequencing of 5’UTR showed Enterovirus Yanbian 96-83csf. 1996 5,000 cases in Yanbian, China. Not previously encountered at PathWest. Scatter across NT. 1st case from Darwin, oil & gas industry, symptoms in co-workers. Spread W and S among indigenous population. Moved into WA, real time surveillance showed spread to e then W Kimberley, Goldfields & eventually SW. Followed movement of aboriginal communities in WA. Also spread around rest of Australia. Only 8 cases in Perth. Reason for unexpectedly low figure unknown. NT peak in < 1 yr; WA peak in 5-14yr group. Active surveillance in NT, passive in WA. Fever mainly in <14yr. Vomiting in most cases > 1yr, reason unknown. No serious sequelae, though mild headache present in small proportion. Surveillance now contributes to growing database at PathWest. Contribute to national enterovirus database.

Notes by TJJI, at 08:45, 23-SEPT-10.

Comments

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