title: Virological and epidemiological analysis of coxsackievirus A24 variant epidemic of acute hemorrhagic conjunctivitis in Okinawa, Japan, in 2011.
abstract: BACKGROUND
  Acute hemorrhagic conjunctivitis (AHC) is a highly contagious enterovirus infection of the conjunctiva and cornea. Coxsackievirus A24 variant (CA24v) is one of its etiological agents. We report a clinical, epidemiological, and virological analysis of a large epidemic of AHC that occurred from May to September, 2011, in Okinawa, Japan.
  
  
  METHODS
  Clinical and epidemic aspects were evaluated for 435 AHC patients (348 bilateral and 87 unilateral, 783 eyes). Virological studies were carried out on nine isolates from ten patients. Virus isolation and direct detection of the enterovirus genome by the reverse transcription polymerase chain reaction method and complete nucleotide sequencing of the VP1 gene and phylogeny-based classification using the VP4 sequences were carried out.
  
  
  RESULTS
  The 11-15-year age group comprised the highest (62.0%) proportion of cases among all age groups. Conjunctival hyperemia was present in all patients, and subconjunctival hemorrhage, superficial punctate keratitis, and preauricular lymphadenopathy were present in 25.4%, 10.3%, and 7.8% of eyes, respectively. CA24v was isolated from the epidemic strain, and phylogenetic analysis based on a fragment of the VP1 gene showed 96%-97% identity between the current strain and the recent China/GD01/2010 strain.
  
  
  CONCLUSIONS
  These findings demonstrate that the clinical and epidemiological features of AHC observed in this study were similar to those of the past epidemic in the same region. It should be noted that sequential outbreaks of AHC due to CA24v might occur in the same location after a considerable period of time, and public health precautions are necessary to control this explosive epidemic.
authors.affiliation: Department of Ophthalmology, Fukuoka University School of Medicine, Fukuoka, Japan.
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Harada
authors.affiliation: Infectious Disease Surveillance Center, National Institute of Infectious Disease, Tokyo, Japan.
authors.forename: Tsuguto
authors.initials: T
authors.lastname: Fujimoto
authors.affiliation: Asato Eye Clinic, Itoman, Japan.
authors.forename: Yoshimori
authors.initials: Y
authors.lastname: Asato
authors.affiliation: Department of Ophthalmology, Fukuoka University School of Medicine, Fukuoka, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Uchio
keywords: acute hemorrhagic conjunctivitis; coxsackievirus; enterovirus; epidemiology; polymerase chain reaction