title: Epidemics of influenza and pediatric diseases observed in infectious disease surveillance in Japan, 1999-2005.
abstract: BACKGROUND
  A method for determining epidemics in small areas from the sentinel surveillance data has been proposed and applied in the National Epidemiological Surveillance of Infectious Diseases (NESID) in Japan. We observed epidemics of influenza and 11 pediatric diseases by the method in the NESID in Japan during 1999-2005.
  
  
  METHODS
  We assumed that an epidemic in a public health center area began in a week when the number of cases reported to the NESID per sentinel clinic and hospital in the area in the week exceeded a given value, and that the epidemic ended when the number was lower than another given value. The proportion of public health center areas with epidemics (epidemic area proportion) by week in fiscal 1999-2005 was calculated. Total public health center area-weeks observed were about 30,000 each year.
  
  
  RESULTS
  The mean epidemic area proportion in the 7 years was 6.0% for influenza and 0.2-7.4% for pediatric diseases. The proportion increased in pharyngoconjunctival fever and group A streptococcal pharyngitis, decreased in measles and was less than 1.0% in pertussis and rubella. In influenza, the height of the peak in the weekly epidemic area proportion varied between 6 and 90% in the 7 years and the week of the peak varied widely. In some pediatric diseases, the height of the peak varied, while the week of the peak was relatively constant.
  
  
  CONCLUSIONS
  The frequency and temporal change were described in the epidemics of influenza and pediatric diseases in public health center areas from the NESID data in Japan, 1999-2005.
authors.affiliation: Department of Public Health, Saitama Medical University Faculty of Medicine, 38 Morohongo, Moroyama-machi, Iruma-gun Saitama 350-0495, Japan. aohta@saitama-med.ac.jp
authors.forename: Akiko
authors.initials: A
authors.lastname: Ohta
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Murakami
authors.forename: Shuji
authors.initials: S
authors.lastname: Hashimoto
authors.forename: Masaki
authors.initials: M
authors.lastname: Nagai
authors.forename: Miyuki
authors.initials: M
authors.lastname: Kawado
authors.forename: Michiko
authors.initials: M
authors.lastname: Izumida
authors.forename: Yuki
authors.initials: Y
authors.lastname: Tada
authors.forename: Mika
authors.initials: M
authors.lastname: Shigematsu
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Yasui
authors.forename: Kiyosu
authors.initials: K
authors.lastname: Taniguchi
mesh_terms: D002648:Child; D003141:Communicable Diseases / Q000453:epidemiology*; D004196:Disease Outbreaks; D006801:Humans; D007251:Influenza, Human / Q000453:epidemiology*; D007564:Japan / Q000453:epidemiology; D010372:Pediatrics; D018571:Sentinel Surveillance; D014777:Virus Diseases / Q000453:epidemiology*