title: A 13-year study of Japanese cedar pollinosis in Japanese schoolchildren.
abstract: BACKGROUND
  Japanese cedar pollen (JCP) sensitization and Japanese cedar pollinosis (JCPS) appear to be increasingly prevalent in younger children. The present study investigated factors affecting JCP sensitization and JCPS development in school children.
  
  
  METHODS
  In May or June each year from 1994 to 2006, 275-510 children were assessed for serum JCP-IgE and house dust mite (HDM)-IgE levels, and surveyed regarding rhinoconjunctival symptoms.
  
  
  RESULTS
  Strong JCP sensitization (IgE > or = 17.5 U(A)/ml) was associated with age (odds ratio (OR) = 2.65), the amount of dispersed pollen in the observed year (OR = 2.03) and in the year following birth (OR = 1.51), the month of birth (OR = 2.18), and the recent birth cohort (OR = 1.96). Symptoms were negatively correlated with the recent birth cohort (OR = 0.69) after adjusting for JCP-IgE levels. Strong HDM sensitization was associated with gender (OR = 0.65 for girls) and the recent birth cohort (OR = 1.76).
  
  
  CONCLUSIONS
  JCP sensitization appeared to be associated with the recent birth cohort and to increases in dispersed pollen just after birth and in the observed season. Although the recent birth cohort was more easily sensitized, they were not more likely to develop symptoms. In contrast to JCP sensitization, strong HDM sensitization appeared to develop prior to commencement of primary school and was more likely to affect boys.
authors.affiliation: Department of Epidemiology for Community Health and Medicine, Kyoto Prefectural University of Medicine, Kamigyo-ku, Kyoto, Japan. kozasa@koto.kpu-m.ac.jp
authors.forename: Kotaro
authors.initials: K
authors.lastname: Ozasa
authors.forename: Takemitsu
authors.initials: T
authors.lastname: Hama
authors.forename: Kenji
authors.initials: K
authors.lastname: Dejima
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Watanabe
authors.forename: Sawako
authors.initials: S
authors.lastname: Hyo
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Terada
authors.forename: Natsuko
authors.initials: N
authors.lastname: Araki
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Takenaka
mesh_terms: D000293:Adolescent; D000367:Age Factors; D000818:Animals; D052179:Antigens, Plant / Q000276:immunology*; D002648:Child; D003233:Conjunctivitis, Allergic / Q000453:epidemiology* / Q000276:immunology; D032485:Cryptomeria / Q000276:immunology*; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007564:Japan / Q000453:epidemiology; D008297:Male; D016017:Odds Ratio; D011058:Pollen / Q000276:immunology*; D039981:Pyroglyphidae / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology* / Q000276:immunology; D018570:Risk Assessment; D012307:Risk Factors; D012737:Sex Factors; D013334:Students / Q000706:statistics & numerical data*; D013997:Time Factors
chemical_list: D052179:Antigens, Plant; D007073:Immunoglobulin E