title: A Five Site Clostridium Perfringens Food-Borne Outbreak: A Retrospective Cohort Study.
abstract: BACKGROUND
  In May of 2012, we investigated a food-borne Clostridium perfringens outbreak in Slovenia involving a single kitchen and five venues, with 477 exposed persons.
  
  
  METHODS
  In order to identify the causative agent, vehicle of infection and source of contamination, we conducted microbiological and environmental investigations and an analytical cohort study (n = 138).
  
  
  RESULTS
  The case definition in the outbreak was met by 104 persons. Predominant symptoms were diarrhoea, nausea and abdominal cramps. Median incubation time and duration of illness were 12 and 22.5 hours respectively. Stool samples were collected from 18 persons and in 13 C. perfringens spores were present; enterotoxin was detected in 9 persons. PCR and PFGE analysis of isolates from a cook with earlier onset time, who did not consume the implicated food, and cases from four venues showed the same strain of C. perfringens type A (with cpe-gene), indistinguishable by PFGE analysis. No food samples could be obtained. An analytical study showed that one food item (French salad) was the most likely vehicle of infection (RR: 6.35; 95% CI: 1.62-24.90).
  
  
  CONCLUSIONS
  This was the largest C. perfringens outbreak in Slovenia to date. Proper analytical study in combination with detailed laboratory investigation with genotypisation enabled us to identify a causative agent, vehicle of infection and possible source of contamination. Fast response and interdisciplinary collaboration led to timely implementation of control measures. These have led to the kitchen acquiring new equipment and improving staff knowledge of risks and processes, thus reducing the likelihood of future reoccurrences.
authors.affiliation: National Institute of Public Health, Regional Unit Nova Gorica, Vipavska cesta 13, 5000 Nova Gorica, Slovenia.
authors.forename: Mario
authors.initials: M
authors.lastname: Fafangel
authors.affiliation: National Institute of Public Health, Communicable Diseases Centre, Zaloška 29, 1000 Ljubljana, Slovenia.
authors.forename: Veronika
authors.initials: V
authors.lastname: Učakar
authors.affiliation: National Institute of Public Health, Regional Unit Nova Gorica, Vipavska cesta 13, 5000 Nova Gorica, Slovenia.
authors.forename: Marko
authors.initials: M
authors.lastname: Vudrag
authors.affiliation: National Laboratory for Health, Environment and Food, Prvomajska 1, 2000 Maribor, Slovenia.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Berce
authors.affiliation: National Institute of Public Health, Communicable Diseases Centre, Zaloška 29, 1000 Ljubljana, Slovenia.
authors.forename: Alenka
authors.initials: A
authors.lastname: Kraigher
keywords: Clostridium perfringens; cohort studies; epidemiology; infectious diseases outbreaks