title: Estimated Number of Patients with Influenza A(H1)pdm09, or Other Viral Types, from 2010 to 2014 in Japan.
abstract: Infectious disease surveillance systems provide information crucial for protecting populations from influenza epidemics. However, few have reported the nationwide number of patients with influenza-like illness (ILI), detailing virological type. Using data from the infectious disease surveillance system in Japan, we estimated the weekly number of ILI cases by virological type, including pandemic influenza (A(H1)pdm09) and seasonal-type influenza (A(H3) and B) over a four-year period (week 36 of 2010 to week 18 of 2014). We used the reported number of influenza cases from nationwide sentinel surveillance and the proportions of virological types from infectious agents surveillance and estimated the number of cases and their 95% confidence intervals. For the 2010/11 season, influenza type A(H1)pdm09 was dominant: 6.48 million (6.33-6.63), followed by types A(H3): 4.05 million (3.90-4.21) and B: 2.84 million (2.71-2.97). In the 2011/12 season, seasonal influenza type A(H3) was dominant: 10.89 million (10.64-11.14), followed by type B: 5.54 million (5.32-5.75). In conclusion, close monitoring of the estimated number of ILI cases by virological type not only highlights the huge impact of previous influenza epidemics in Japan, it may also aid the prediction of future outbreaks, allowing for implementation of control and prevention measures.
authors.affiliation: Department of Medical Statistics, Toho University, Tokyo, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Murakami
authors.affiliation: Department of Hygiene, Fujita Health University School of Medicine, Aichi, Japan.
authors.forename: Shuji
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: Department of Hygiene, Fujita Health University School of Medicine, Aichi, Japan.
authors.forename: Miyuki
authors.initials: M
authors.lastname: Kawado
authors.affiliation: Department of Public Health, Saitama Medical University Faculty of Medicine, Saitama, Japan.
authors.forename: Akiko
authors.initials: A
authors.lastname: Ohta
authors.affiliation: Department of Pediatrics, National Mie Hospital, Mie, Japan.
authors.forename: Kiyosu
authors.initials: K
authors.lastname: Taniguchi
authors.affiliation: Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Tomimasa
authors.initials: T
authors.lastname: Sunagawa
authors.affiliation: Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Tokyo, Japan.
authors.forename: Tamano
authors.initials: T
authors.lastname: Matsui
authors.affiliation: Department of Public Health, Saitama Medical University Faculty of Medicine, Saitama, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Nagai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks / Q000706:statistics & numerical data; D058872:Epidemics / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D009980:Influenza A virus / Q000145:classification* / Q000235:genetics; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology*; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D012621:Seasons; D018571:Sentinel Surveillance; D055815:Young Adult