No longitudinal molecular epidemiology of parechovirus A3 (PeV-A3) over a decade is available and PeV-A3-associated myalgia/myositis has been reported only in Japan. Thus, we aimed to clarify the longitudinal molecular epidemiology of PeV-A3 with a major focus on the strains detected from PeV-A3-associated myalgia/myositis cases. We performed sequence and phylogenetic analysis for the VP1 region of PeV-A3 strains in Yamagata, Japan, between 2003 and 2016. The phylogenetic analysis indicated that PeV-A3 strains caused PeV-A3-associated myalgia/myositis as well as a variety of infectious diseases, ranging from mild to severe, in subjects ranging from neonates to adults, irrespective of genetic cluster or variations. PeV-A3 strains are causative agents of a variety of human diseases, irrespective of their genetic cluster. Furthermore, we consider that PeV-A3-associated myalgia/myositis may occur, not only in Japan, but also in other countries, as closely related PeV-A3 strains have been circulating around the world.
Keywords: PeV-A3-associated myalgia/myositis; epidemic myalgia; molecular epidemiology; parechovirus A3.