title: An outbreak of Streptococcus equi subspecies zooepidemicus associated with consumption of fresh goat cheese.
abstract: BACKGROUND
  Streptococcus equi subspecies zooepidemicus is a rare infection in humans associated with contact with horses or consumption of unpasteurized milk products. On October 23, 2003, the National Public Health Institute was alerted that within one week three persons had been admitted to Tampere University Central Hospital (TaYS) because of S. equi subsp. zooepidemicus septicaemia. All had consumed fresh goat cheese produced in a small-scale dairy located on a farm. We conducted an investigation to determine the source and the extent of the outbreak.
  
  
  METHODS
  Cases were identified from the National Infectious Disease Register. Cases were persons with S. equi subsp. zooepidemicus isolated from a normally sterile site who had illness onset 15.9-31.10.2003. All cases were telephone interviewed by using a standard questionnaire and clinical information was extracted from patient charts. Environmental and food specimens included throat swabs from two persons working in the dairy, milk from goats and raw milk tank, cheeses made of unpasteurized milk, vaginal samples of goats, and borehole well water. The isolates were characterized by ribotyping and pulsed-field gel electrophoresis (PFGE).
  
  
  RESULTS
  Seven persons met the case definition; six had septicaemia and one had purulent arthritis. Five were women; the median age was 70 years (range 54-93). None of the cases were immunocompromized and none died. Six cases were identified in TaYS, and one in another university hospital in southern Finland. All had eaten goat cheese produced on the implicated farm. S. equi subsp. zooepidemicus was isolated from throat swabs, fresh goat cheese, milk tank, and vaginal samples of one goat. All human and environmental strains were indistinguishable by ribotyping and PFGE.
  
  
  CONCLUSIONS
  The outbreak was caused by goat cheese produced from unpasteurized milk. Outbreaks caused by S. equi subsp. zooepidemicus may not be detected if streptococcal strains are only typed to the group level. S. equi subsp. zooepidemicus may be a re-emerging disease if unpasteurized milk is increasingly used for food production. Facilities using unpasteurized milk should be carefully monitored to prevent this type of outbreaks.
authors.affiliation: Department of Infectious Disease Epidemiology, National Public Health Institute (KTL), Helsinki, Finland. markku.kuusi@ktl.fi
authors.forename: Markku
authors.initials: M
authors.lastname: Kuusi
authors.forename: Elina
authors.initials: E
authors.lastname: Lahti
authors.forename: Anni
authors.initials: A
authors.lastname: Virolainen
authors.forename: Maija
authors.initials: M
authors.lastname: Hatakka
authors.forename: Risto
authors.initials: R
authors.lastname: Vuento
authors.forename: Leila
authors.initials: L
authors.lastname: Rantala
authors.forename: Jaana
authors.initials: J
authors.lastname: Vuopio-Varkila
authors.forename: Eija
authors.initials: E
authors.lastname: Seuna
authors.forename: Matti
authors.initials: M
authors.lastname: Karppelin
authors.forename: Marjaana
authors.initials: M
authors.lastname: Hakkinen
authors.forename: Johanna
authors.initials: J
authors.lastname: Takkinen
authors.forename: Veera
authors.initials: V
authors.lastname: Gindonis
authors.forename: Kyosti
authors.initials: K
authors.lastname: Siponen
authors.forename: Kaisa
authors.initials: K
authors.lastname: Huotari
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D002611:Cheese / Q000382:microbiology*; D004196:Disease Outbreaks; D005260:Female; D005387:Finland / Q000453:epidemiology; D005516:Food Microbiology; D006041:Goats / Q000382:microbiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013290:Streptococcal Infections / Q000453:epidemiology* / Q000382:microbiology*; D018502:Streptococcus equi / Q000302:isolation & purification*