Tuesday, 16 February 2016

Human parechovirus (HPeV) may be spread with the help of well kids...

UPDATES: #1 17FEB2016 AEST
#2: 10AUG2016 AEST

The first human parechoviruses (HPeVs) were initially called Human echovirus 22 (HPeV-1) and Human echovirus 23 (HPeV-2).[11,12] These guys were discovered in the summer of 1956 but they weren't officially renamed, and put into their own genus, until 1996.[1]

This very month the genus was officially split into two species, Parechovirus A (containing the 16 human parechoviruses) and Parechovirus B (containing 4 Ljungan viruses).[2,3]

HPeVs are usually summertime viruses and they are not that unusual although there is still plenty to learn about them. They usually show up, or make the news, when more severe infections drive small children to hospital with central nervous system disturbances.[6,7] It has been assumed that they're spread by contact and also by droplets via the respiratory tract and the faecal-oral route. HPeVs can be detected in the nasopharynx, throat, blood  as well as cerebrospinal fluid and in faeces - usually using RT-PCR technologies.[8]

After a study last year,[4] its authors found that within families in Japan, genetically identical HPeV variants could be identified among both sick and well members. They speculated that aymptomatic infections might be a source of spread of infectious HPeV to others in such a close quartered environment. 

While HPeVs were sometimes found in the absence of any signs of illness in this study, some family members showed the more serious end of an HPeV infection - encephalitis, septic shock as well as fever, vomiting and diarrhoea.[4]

There are no specific antiviral drugs available to treat HPeV and no vaccine exists. Supportive treatment is recommended for serious illness and most, although not all, serious cases reportedly recover without any later problems, although long-term studies are needed.[9,10,8] The best prevention is consistent hand hygiene after nose wiping, going to the toilet or changing nappies and coughing and sneezing into a tissue which is then discarded.[5]

Once again we see that a virus found in patients with severe disease, can also be found in a person without any disease. The outcome from a virus infection is best considered as sitting somewhere along a sliding scale and which will vary from animal-to-animal. Just don't lump the outcome into any one particular box.

References...
  1. http://www.picornastudygroup.com/taxa/genera.htm
  2. http://www.picornastudygroup.com/taxa/species/species.htm
  3. http://www.ictvonline.org/proposals/2014.016aV.A.v1.Picornaviridae_spren.pdf
  4. http://www.ncbi.nlm.nih.gov/pubmed/26305831
  5. http://www.health.nsw.gov.au/Infectious/factsheets/Pages/parechovirus.aspx
  6. http://virologydownunder.blogspot.com.au/2013/12/what-to-watch-for-with-human.html
  7. http://virologydownunder.blogspot.com.au/2013/11/parechovirus-infections-in-babies-in.html
  8. http://www.ncbi.nlm.nih.gov/pubmed/21736976
  9. http://www.ncbi.nlm.nih.gov/pubmed/25301212
  10. http://www.ncbi.nlm.nih.gov/pubmed/23810613
  11. http://www.ncbi.nlm.nih.gov/pubmed/13785166
  12. http://www.ncbi.nlm.nih.gov/pubmed/13538681
Updates...
  1. Added 2 references
  2. Note that one Echovirus 23 (CT86-6760) is not an HPeV-2, but a misclassified HPeV-5 - Al-Sunaidi et al. J Virol 81;2. 1013-1021

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