title: Identification of Kudoa septempunctata as the causative agent of novel food poisoning outbreaks in Japan by consumption of Paralichthys olivaceus in raw fish.
abstract: BACKGROUND
  Outbreaks of an unidentified food-borne illness associated with the consumption of raw fish have increased in Japan since 2003. Those affected with this illness develop diarrhea and emesis within 2-20 hours after a meal including raw fish. No known causative agents such as bacteria, viruses, bacterial toxins, or toxic chemicals have been detected in the foods that were ingested. Fortunately, this illness is self-limiting with good prognosis in all cases.
  
  
  METHODS
  We conducted an epidemiological analysis of outbreaks that occurred during 2008 and 2010 and analysed a fish sample from one outbreak by metagenomic DNA sequencing, real-time polymerase chain reaction, and direct microscopic observations. The pathogenicity of a putative risk factor identified by these techniques was assessed using the suckling-mouse test and a house musk shrew emetic assay.
  
  
  RESULTS
  The epidemiological analysis of outbreaks in 24 municipalities involving >1300 subjects implicated an olive flounder (Paralichthys olivaceus) as the causative food source. The presence of Kudoa septempunctata, a recently-described myxosporean species in P. olivaceus, was prevalent in the causative foods. K. septempunctata induced watery stools and an elevated fluid accumulation ratio in suckling mice, as well as vomiting in house musk shrews.
  
  
  CONCLUSIONS
  These results identify K. septempunctata as the etiological agent of this novel food-borne illness outbreak associated with consumption of raw P. olivaceus. This is the first report, to our knowledge, demonstrating the human pathogenicity of Kudoa spores.
authors.affiliation: Division of Bacteriology, Osaka Prefectural Institute of Public Health, Kobe Institute of Health, Kobe, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Kawai
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Sekizuka
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Yahata
authors.forename: Makoto
authors.initials: M
authors.lastname: Kuroda
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kumeda
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Iijima
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Kamata
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Sugita-Konishi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Ohnishi
mesh_terms: D000818:Animals; D003967:Diarrhea / Q000175:diagnosis / Q000209:etiology; D004195:Disease Models, Animal; D004196:Disease Outbreaks; D005247:Feeding Behavior; D005260:Female; D005412:Flatfishes / Q000469:parasitology*; D005517:Foodborne Diseases / Q000175:diagnosis* / Q000469:parasitology*; D006801:Humans; D007564:Japan; D008297:Male; D054892:Metagenome; D051379:Mice; D008853:Microscopy; D055764:Myxozoa / Q000302:isolation & purification*; D010272:Parasitic Diseases / Q000175:diagnosis* / Q000469:parasitology*; D060888:Real-Time Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014839:Vomiting / Q000175:diagnosis / Q000209:etiology