title: Important vectors for Listeria monocytogenes transmission at farm dairies manufacturing fresh sheep and goat cheese from raw milk.
abstract: The aim of this study was to determine the transmission routs of Listeria spp. in dairy farms manufacturing fresh cheese made from ovine and caprine raw milk and to evaluate the impact of Listeria monocytogenes mastitis on raw milk contamination. Overall, 5,799 samples, including 835 environmental samples, 230 milk and milk product samples, and 4,734 aseptic half-udder foremilk samples were collected from 53 dairy farms in the dairy intensive area of Lower Austria. Farms were selected for the study because raw milk was processed to cheese that was sold directly to consumers. A total of 153 samples were positive for Listeria spp., yielding an overall prevalence of 2.6%; L. monocytogenes was found in 0.9% of the samples. Bulk tank milk, cheese, and half-udder samples were negative for Listeria spp. Because none of the sheep and goats tested positive from udder samples, L. monocytogenes mastitis was excluded as a significant source of raw milk contamination. L. monocytogenes was detected at 30.2% of all inspected farms. Swab samples from working boots and fecal samples had a significantly higher overall prevalence (P < 0.001) of L. monocytogenes (15.7 and 13.0%, respectively) than did swab samples from the milk processing environment (7.9%). A significant correlation was found between the prevalence of L. monocytogenes in the animal and in the milk processing environment and the silage feeding practices. Isolation of L. monocytogenes was three to seven times more likely from farms where silage was fed to animals throughout the year than from farms where silage was not fed to the animals.
authors.affiliation: Institute of Milk Hygiene, Milk Technology and Food Science, Veterinary Medical University of Vienna, Veterinärplatz 1, 1210 Vienna, Austria. dagmar.schoder@vetmeduni.ac.at
authors.forename: Dagmar
authors.initials: D
authors.lastname: Schoder
authors.forename: Daniela
authors.initials: D
authors.lastname: Melzner
authors.forename: Alois
authors.initials: A
authors.lastname: Schmalwieser
authors.forename: Abdoulla
authors.initials: A
authors.lastname: Zangana
authors.forename: Petra
authors.initials: P
authors.lastname: Winter
authors.forename: Martin
authors.initials: M
authors.lastname: Wagner
mesh_terms: D000821:Animal Feed / Q000382:microbiology; D000818:Animals; D002611:Cheese / Q000382:microbiology; D003257:Consumer Product Safety; D003612:Dairying / Q000379:methods / Q000592:standards*; D004783:Environmental Microbiology; D004866:Equipment Contamination; D005243:Feces / Q000382:microbiology; D005260:Female; D005430:Floors and Floorcoverings; D005506:Food Contamination / Q000032:analysis* / Q000517:prevention & control; D005525:Food-Processing Industry / Q000379:methods / Q000592:standards; D006041:Goats; D006920:Hygiene; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D008413:Mastitis / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary; D008892:Milk / Q000382:microbiology*; D012756:Sheep; D012820:Silage / Q000382:microbiology