title: [An autochthonous outbreak of dengue type 1 in Tokyo, Japan 2014].
abstract: OBJECTIVE
  An outbreak of autochthonous dengue fever was reported in August 2014, with cases suspected mainly from Yoyogi Park in Tokyo. This is the first epidemic of dengue fever in Japan since 1945.
  
  
  METHODS
  From August to October 2014, the following measures were taken to control the outbreak: 1) risk communication and information sharing; 2) active case finding; 3) vector surveillance in affected sites; and 4) laboratory testing. We also reviewed the surveillance data as reported to the National Epidemiological Surveillance of Infectious Diseases during the 44 epidemiological weeks. results: An official dengue fever call center was set up temporarily for the general public and 3,005 calls were received. The Tokyo Metropolitan Government issued 39 press releases regarding patients and nine related to dengue virus (DENV) detection and vector control activities for the media. Confirmed autochthonous dengue fever cases were reported between the 35th and 44th epidemiological weeks. Out of 160 cases of outbreak, 108 (67.5%) confirmed cases were reported in Tokyo. The estimated illness onset dates were between August 9 and October 7, and estimated dates of infections were between August 3 and October 3, 2014. The data suggest that the infective mosquitoes had already been present in Yoyogi Park at the end of July 2014. During the weekly vector surveillance at Yoyogi Park, a total of 1,152 adult mosquitoes, of which 856 (73.3%) were Aedes mosquitoes, were collected over 11 weeks by a light trap with dry ice. DENV was detected from adult Aedes mosquito samples collected on the 2nd, 9th, and 16th of September, 2014. Serum samples from 240 suspected cases were examined at the Tokyo Metropolitan Institute of Public Health, and 78 were positive for the DENV NS1 antigen, DENV-specific IgM antibody, or DENV nucleic acid with reverse transcriptase polymerase chain reaction (RT-PCR) (NS1: 66 cases; IgM: 50 cases; PCR: 57 cases). Genetic analysis of DENV-positive serum and mosquito samples found all to be categorized as DENV-serotype 1 (gene type I). Phylogenetic analysis of the envelope protein genome sequence from patients and mosquitoes in Tokyo revealed more than 99% similarity with each other and with the strain from the first outbreak-associated patient in Saitama.
  
  
  CONCLUSIONS
  Measures important for control of infectious disease epidemic were learned during this recent indigenous dengue outbreak in Tokyo. It also highlighted the importance of preparedness for epidemics of indigenous or imported infectious diseases, especially in light of the fact that Tokyo is in preparation for the Olympic and Paralympic Games in 2020.
authors.affiliation: Health Risk Management and Communication Section, Department of Planning and Coordination, Tokyo Metropolitan Institute of Public Health Hyakunincho.
authors.forename: Naomi
authors.initials: N
authors.lastname: Seki
authors.forename: Yuko
authors.initials: Y
authors.lastname: Iwashita
authors.forename: Ryoko
authors.initials: R
authors.lastname: Moto
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kamiya
authors.forename: Masayuki
authors.initials: M
authors.lastname: Kurita
authors.forename: Narumi
authors.initials: N
authors.lastname: Tahara
authors.forename: Michiya
authors.initials: M
authors.lastname: Hasegawa
authors.forename: Takayuki
authors.initials: T
authors.lastname: Shinkai
authors.forename: Yukinao
authors.initials: Y
authors.lastname: Hayashi
authors.forename: Kenji
authors.initials: K
authors.lastname: Sadamasu
authors.forename: Akemi
authors.initials: A
authors.lastname: Kai
authors.forename: Yukiko
authors.initials: Y
authors.lastname: Nakajima
authors.forename: Hirotoshi
authors.initials: H
authors.lastname: Watase
authors.forename: Takashi
authors.initials: T
authors.lastname: Ueda
authors.forename: Hideo
authors.initials: H
authors.lastname: Maeda
authors.forename: Kazushi
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Yasue
authors.initials: Y
authors.lastname: Ishizaki
authors.forename: Kyoko
authors.initials: K
authors.lastname: Hiromatsu
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D003715:Dengue / Q000453:epidemiology* / Q000517:prevention & control; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D033181:Information Dissemination; D008297:Male; D008875:Middle Aged; D014041:Tokyo / Q000453:epidemiology