[Results of a survey of Japanese cedar pollinosis in Hachijyojima].

We performed a questionnaire survey of Japanese cedar pollinosis among 7,946 residents of the Sakashita region (Mitsune, Ogago) and Sakaue region (Kashidate, Sueyoshi, Nakanogo) of Hachijyojima who were at least 15 years of age. The response rate was 21.3%. The percentage of respondents who reported three or more nasal symptoms concurrentry with two ocular symptoms in early spring (from the end of February to the end of March) was 1.8% in the Sakashita region and 0.3% in the Sakaue region. About 1.5% of Hachijyojima residents were suspected to have Japanese cedar pollinosis. On scratch tests of symptomatic subjects, 9.2% showed positive reactions for Japanese cedar antigen, and 12.1% had an IgE RAST score of 2 or more. The peak Japanese cedar pollen concentration between February 11 and March 31, 1992 was 74/cm2 on March 6 in the Sakashita region and 127/cm2 on the same day in the Sakaue region. This survey confirmed the presence of a low incidence of Japanese cedar pollinosis in Hachijyojima, an isolated island 290 km from Tokyo.