An outbreak of acute hemorrhagic conjunctivitis due to coxsackie virus type A24 variant in Japan

An outbreak of acute conjunctivitis due to Coxsackie virus A24 (CA24) occurred in Okinawa, the southernmost island of Japan, from 1985 to 1986. From conjunctival scrapings of 85 acute hemorrhagic conjunctivitis patients, 39 isolates identified as an antigenic variant of CA24 were obtained and then cultured in HeLa cells. Paired sera taken from these patients with acute conjunctivitis in Okinawa were also tested against enterovirus 70 (EV70) and CA24 and showed rises in neutralizing antibodies to these agents. The subconjunctival hemorrhage among the clinical manifestations caused by the CA24 variant in this recent epidemic was similar to that due to EV70. EV70 conjunctivitis is more commonly known as acute hemorrhagic conjunctivitis (AHC), first named by the Japanese ophthalmologist, Prof. Seiji Sugiura. The present seroepidemiologic survey for the CA24 variant and EV70 in different districts of Japan revealed a low frequency of rise in neutralizing antibody titers against these two pathogens. The differentiation between EV70 and the CA24 variant as the agent causing AHC is very important in epidemiology, especially as there is a high possibility in Japan of outbreaks caused by these two agents.