Proposal for the Recognition of a New Disease Concept from Japan: Parechovirus A3-Associated Myalgia

Jpn J Infect Dis. 2021 Jul 21;74(4):259-272. doi: 10.7883/yoken.JJID.2020.967. Epub 2020 Dec 25.


Parechovirus A3 (PeVA3) was first reported in 2004 and has been recognized as a causative agent of mild and severe infectious diseases in children. We first reported an outbreak of PeVA3-associated myalgia (PeVA3-M) in Yamagata, Japan, in 2008. We have repeatedly observed PeVA3-M cases in 2011, 2014, and 2016, and identified the first child case in 2014. Reports of PeVA3-M have increased since 2014, indicating that the recognition of PeVA3-M has spread across Japan. The findings showed that PeVA3-M commonly occurs among adults aged 30-40 years, particularly in males. Elevation of creatinine phosphokinase, C-reactive protein, and myoglobin, as well as magnetic resonance imaging findings, suggest inflammation of the muscles and/or fascia of the four limbs. Patients recover within 1-2 weeks without any sequelae. A longitudinal molecular epidemiological study in Yamagata revealed that PeVA3 strains cause a variety of diseases, ranging from mild to severe, including PeVA3-M, in subjects ranging from neonates to adults, irrespective of their genetic cluster. As PeVA3-M has not yet been reported abroad, more widespread recognition of PeVA3-M as an emerging disease is important. We hope this review will help clinicians and researchers in understanding PeVA3-M and therefore advance related research in Japan as well as around the world.

Keywords: PeVA3-associated myalgia; emerging disease; epidemic myalgia; parechovirus A3.

Publication types

  • Review

MeSH terms

  • Humans
  • Japan / epidemiology
  • Myalgia / epidemiology
  • Myalgia / pathology
  • Myalgia / virology*
  • Parechovirus / classification*
  • Picornaviridae Infections / complications*
  • Picornaviridae Infections / epidemiology
  • Picornaviridae Infections / virology*