title: Risk factors for Salmonella enterica subsp. enterica contamination in 519 French laying hen flocks at the end of the laying period.
abstract: A cross-sectional study was carried out to identify risk factors for Salmonella spp. contamination in French laying hen flocks at the end of the laying period. Five hundred and nineteen flocks were studied between October 2004 and September 2005. The Salmonella status of the flocks was assessed from 5 faeces samples (pooled faeces samples from cage flocks and foot swabs from flocks kept on the floor, i.e. in a barn, outdoors and on organic farms) and 2 dust samples analysed using a classical bacteriological method. At least one contaminated sample was found in 93 flocks and the apparent prevalence of Salmonella was 17.9% (CI 95%=14.5, 21.3). Prevalence was significantly higher in caged flocks than in on-floor flocks and logistic-regression models were built for each subpopulation. Associations between farm characteristics, managerial practices and the presence of one or more Salmonella-positive samples in a flock were assessed using a mixed logistic-regression model with a flock-specific random effect. In caged flocks (n=227) the risk of Salmonella contamination increased with flock size and when delivery trucks passed near poultry-house entrances. The risk of detecting a positive sample was lower with pooled faeces samples than with dust samples. In on-floor flocks (n=292), a higher risk of contamination was associated with multistage management (presence of hens of different ages on the farm) and contamination by Salmonella Enteritidis of a previous flock kept on the farm. However, the use of a container for dead bird disposal was a protective factor.
authors.affiliation: AFSSA-Ploufragan, Laboratoire d'Etudes et de Recherches Avicoles, Porcines et Piscicoles, BP 53, Ploufragan F-22440, France. a.huneau@afssa.fr
authors.forename: Adeline
authors.initials: A
authors.lastname: Huneau-Salaün
authors.forename: Chemaly
authors.initials: C
authors.lastname: Marianne
authors.forename: Le Bouquin
authors.initials: le B
authors.lastname: Sophie
authors.forename: Lalande
authors.initials: L
authors.lastname: Françoise
authors.forename: Petetin
authors.initials: P
authors.lastname: Isabelle
authors.forename: Rouxel
authors.initials: R
authors.lastname: Sandra
authors.forename: Michel
authors.initials: M
authors.lastname: Virginie
authors.forename: Fravalo
authors.initials: F
authors.lastname: Philippe
authors.forename: Rose
authors.initials: R
authors.lastname: Nicolas
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D002645:Chickens / Q000382:microbiology*; D003430:Cross-Sectional Studies; D005243:Feces / Q000382:microbiology; D005260:Female; D005506:Food Contamination / Q000517:prevention & control; D005602:France / Q000453:epidemiology; D006799:Housing, Animal; D006801:Humans; D016015:Logistic Models; D010058:Oviposition; D011156:Population Density; D011201:Poultry Diseases / Q000453:epidemiology* / Q000517:prevention & control; D015995:Prevalence; D012307:Risk Factors; D012481:Salmonella Infections, Animal / Q000453:epidemiology* / Q000517:prevention & control; D019779:Salmonella enterica