A molecular epidemiologic study of human adenovirus type 8 isolates causing epidemic keratoconjunctivitis in Kawasaki City, Japan in 2011.

A local outbreak of epidemic keratoconjunctivitis (EKC) caused by human adenovirus type 8 (HAdV-D8) occurred in Kawasaki city, Japan in July–August 2011. Since the cases were sporadic in nature, the source of the infection could not be identified. The results of PCR analysis and the appearance of cytopathic effects in the samples indicated that 22 patients were positive for HAdV. The mean age of the patients (10 men and 12 women) was 64.3± 17.3 years (median, 68 years; range, 11–86 years). The sequences of hexon, which included hypervariable loop 1; the penton, which included RGD loops; and the fiber, which included the knob-coding regions, were identical in all the HAdV-positive cases. Phylogenetic analysis of the major capsid protein-encoding regions of HAdV confirmed that the isolates were HAdV-D8. Although the incidence of HAdV-D8 outbreaks has decreased in Japan since 1997, the results of our study imply that HAdV-D8 is still a causative agent for EKC outbreaks in Japan.