[Epidemic of influenza in Kyushu-Okinawa District (April 1994-March 1995)]

The prevalence of influenza in Kyushu-Okinawa District in April 1994- March 1995 was studied as the prevalence of influenza virus, to determine the sero-type of influenza viruses isolated in Kyushu- Okinawa District prefectures and cities. As a result, three sero-types of influenza viruses, i.e. type A/H1N1, type H3N2 and type B, were isolated in Kyushu-Okinawa District in this season, but most of the isolates were type A/H3N2 and type B. Weekly changes of reported influenza patients and period of virus isolation at local public health institutes revealed that influenza epidemics of the earlier part in this season was caused by type A/H3N2 and the latter part due to type B. Type A/H3N2 spread all over Kyushu-Okinawa District in a shorter period (about 2 weeks) through the westside of Kyushu and down south, and type B stayed about one month in northern Kyushu and took about 7 weeks to spread all over Kyushu-Okinawa District. Based on these results, the spread of influenza virus in Kyushu-Okinawa District was visualized on the isopleth maps.