ABSTRACT
A large outbreak of Yersinia pseudotuberculosis O:1 infection affected over 400 children from 23 schools and 5 day-care centres in two municipalities in southern Finland in August-September, 2006. A retrospective cohort study conducted in a large school centre showed that the outbreak was strongly associated with the consumption of grated carrots served at a school lunch. The risk of illness increased with the amount of carrots eaten. Poor quality carrots grown the previous year had been delivered to the school kitchens in the two municipalities affected. In the patients' samples and in the environmental samples collected from the carrot distributor's storage facility, identical serotypes and genotypes of Y. pseudotuberculosis were found, but the original source and the mechanism of the contamination of the carrots remained unclear. Outbreaks of Y. pseudotuberculosis linked to fresh produce have been detected repeatedly in Finland. To prevent future outbreaks, instructions in improved hygiene practices on the handling of raw carrots have been issued to farmers, vegetable-processing plants and institutional kitchens.
Subject(s)
Daucus carota/microbiology , Disease Outbreaks , Food Microbiology , Foodborne Diseases/epidemiology , Foodborne Diseases/microbiology , Yersinia pseudotuberculosis Infections/epidemiology , Yersinia pseudotuberculosis/isolation & purification , Adolescent , Adult , Chi-Square Distribution , Child , Female , Finland/epidemiology , Food Contamination , Food Handling , Humans , Incidence , Male , Middle Aged , Retrospective StudiesABSTRACT
Multiple gastroenteritis outbreaks occurred between 25 and 31 July 2006 in 10 workplace canteens in south-western Finland. One vegetable processing plant provided raw vegetables to all the canteens. We conducted cohort studies in the three most visited canteens and environmental investigations in the kitchens and the plant. Patients' stools, food, water and environmental samples were tested for enteric bacteria and viruses. Of the three canteens, 150/273 respondents (response rate 82%) had gastroenteritis. Consumption of mixed raw vegetables was significantly associated with the illness but no single vegetable explains the outbreak. An identical norovirus GII.1 genotype was detected from all genotyped patient samples. Water, food, and environmental samples were negative for norovirus. The facilities had appropriate hygienic conditions and no staff member had gastroenteritis prior to the outbreak. Tracing back the vegetables to the farm level proved unsuccessful. This was the largest foodborne norovirus outbreak in Finland.
