title: Group B streptococcal disease in infants in the first year of life: a nationwide surveillance study in Japan, 2011-2015.
abstract: OBJECTIVE
  This study aimed to describe the epidemiology of childhood group B streptococcus (GBS) disease including late late-onset disease (LLOD) and to clinically characterize recurrent cases and twin-sibling cases in Japan.
  
  
  METHODS
  We collected information on infants (<1 year of age) with invasive GBS disease and institutional information about births and transfers through a nationwide questionnaire between 2011 and 2015.
  
  
  RESULTS
  We identified 133 infants with early-onset disease (EOD), 274 late-onset disease (LOD), and 38 LLOD from 149 institutes. The case fatality rate (CFR) of EOD, LOD, and LLOD was 4.5, 4.4, and 0%, respectively. CFR in EOD was significantly (P < 0.001) associated with preterm birth, but not that in LOD and LLOD. Twenty-nine percent of infants with meningitis (49/169) had neurologic sequelae. We showed clinical details of 12 recurrent cases that accounted for 2.8% of the total patients, and 4 sets of both twins affected; 4 of 12 recurrent cases and 3 of 4 twin-sibling sets were also associated with preterm birth. Based on the livebirth number of 581,488, the instituted-based incidence of EOD, LOD, and LLOD was estimated as 0.09 (95% CI 0.06-0.11), 0.12 (95% CI 0.11-0.14), and 0.01 (95% CI 0.01-0.02) per 1000 livebirths, respectively.
  
  
  CONCLUSIONS
  CFR of EOD and LOD in Japan is comparable with that in high-income European countries or the United States, and their incidence is much lower. Our findings also describe the clinical details of LLOD, recurrent infections, and infections in twin siblings. This study is the largest among Asian childhood GBS studies ever reported.
authors.affiliation: Department of Pediatrics, Nishi-Kobe Medical Center, 5-7-1 Kojidai, Nishi-ku, Kobe, 651-2273, Japan. kskmatsu@s4.dion.ne.jp.
authors.forename: Kousaku
authors.initials: K
authors.lastname: Matsubara
authors.affiliation: Department of Pediatrics, Sanno Hospital, Tokyo, Japan.
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Hoshina
authors.affiliation: Department of Neonatology, Tokyo Metropolitan Children's Medical Center, Tokyo, Japan.
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Kondo
authors.affiliation: Division of Infectious Diseases, National Center for Child Health and Development, Tokyo, Japan.
authors.forename: Isao
authors.initials: I
authors.lastname: Miyairi
authors.affiliation: Department of Neonatology, Ibaraki Children's Hospital, Ibaraki, Japan.
authors.forename: Yoshiya
authors.initials: Y
authors.lastname: Yukitake
authors.affiliation: Department of Pediatric Intensive Care, Shizuoka Children's Hospital, Shizuoka, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ito
authors.affiliation: Department of General Pediatrics, Nagano Children's Hospital, Azumino, Nagano, Japan.
authors.forename: Kisei
authors.initials: K
authors.lastname: Minami
authors.affiliation: Department of Neonatology, Okinawa Chubu Hospital, Uruma, Okinawa, Japan.
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Genkawa
mesh_terms: D004200:Diseases in Twins / Q000453:epidemiology* / Q000382:microbiology; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007564:Japan / Q000453:epidemiology; D008297:Male; D008581:Meningitis / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D009422:Nervous System Diseases / Q000453:epidemiology* / Q000382:microbiology; D012008:Recurrence; D013290:Streptococcal Infections / Q000150:complications / Q000453:epidemiology* / Q000382:microbiology; D013292:Streptococcus agalactiae / Q000502:physiology*
keywords: Epidemiology; Group B Streptococcus; Japan; Recurrence; Streptococcus agalactiae; Twin