[Long-term time series analysis of epidemic keratoconjunctivitis in Okinawa Prefecture, Japan]

Epidemic keratoconjunctivitis (EKC) is a highly infectious disease caused by an adenovirus and is associated with nosocomial or endemic infections. In a series analysis before 1993, we predicted that EKC patients would decrease in Okinawa. We analyzed the number of EKC patients after 1993 in the same area to confirm the compatibility between measured and predicted epidemic curves.

The numbers of EKC patients reported by the National Epidemic Surveillance Report of Japan between 1993 and 2003 in Okinawa were analyzed by time series analysis.

The epidemic curve showed a peak in late 1995 and the number decreased thereafter. Among epidemic tendency curves, an exponential curve fitted best to the measured curve and this result was compatible with our past prediction.

The similarity of the epidemic curve analyzed by long-term time series analysis and the previously predicted curve of EKC in Okinawa, Japan, supports the epidemiological hypothesis that Okinawa is an epidemiologically isolated island for EKC, and its population can be deemed a theoretical epidemiologically closed group.