title: Contamination of pigs by nose-to-nose contact or airborne transmission of Salmonella Typhimurium.
abstract: The aim of this study is to assess the risk of contamination by Salmonella Typhimurium of pigs by nose-to-nose contact or the airborne route. Thirty twelve-week-old SPF pigs were divided into 4 groups housed in 4 different rooms: the first room contained Salmonella-free control pigs (n = 4), the second room had 10(3) CFU S. Typhimurium inoculated pigs (n = 5) and non-inoculated "contact" pigs (n = 4), the third room had pigs (n = 8) receiving potentially contaminated air from the following room through a hole (4 pigs housed in the pen situated near the hole and 4 pigs in the pen at the opposite side of the room), and the fourth room had pigs (n = 5) inoculated with 10(6) CFU Salmonella Typhimurium and also non inoculated "contact" pigs (n = 4). The "contact" and the inoculated pigs were housed in adjacent pens allowing nose-to-nose contact. The 5 pigs orally inoculated with 10(6) CFU S. Typhimurium were bacteriologically and serologically positive 1 week later and their environment was contaminated as early as 1 day pi. The faecal samples of 4 nose-to-nose contact pigs were bacteriologically positive and one of them was seropositive 5 weeks pi before the pigs were commingled. The 8 pigs housed in the third room received S. Typhimurium by an active airflow coming from the contaminated room (1000 m3/hour). Their faecal samples remained negative until 8 weeks pi but the environmental swabs taken in the room close to the airinlet were contaminated 2 days pi and positive swabs were found elsewhere in the room 5 weeks pi. Two seropositive pigs were encountered 8 weeks pi in the pen situated near the hole. Only one among the 5 pigs inoculated with 10(3) CFU had bacteriologically positive faeces 1-week pi and the 4 pigs kept in nose-to-nose contact with them remained negative. A dose of 10(3) CFU was too small to induce persistent excretion and to stimulate a humoral immune response. However, the dose of 10(6) CFU induced contamination of nose-to-nose contact pigs and contamination of the environment by airflow.
authors.affiliation: AFSSA Ploufragan, Zoopĵle Beaucemaine, France. k.proux@ploufragan.afssa.fr
authors.forename: K
authors.initials: K
authors.lastname: Proux
authors.forename: R
authors.initials: R
authors.lastname: Cariolet
authors.forename: P
authors.initials: P
authors.lastname: Fravalo
authors.forename: C
authors.initials: C
authors.lastname: Houdayer
authors.forename: A
authors.initials: A
authors.lastname: Keranflech
authors.forename: F
authors.initials: F
authors.lastname: Madec
mesh_terms: D000391:Air Microbiology; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D015169:Colony Count, Microbial / Q000662:veterinary; D018562:Disease Transmission, Infectious / Q000662:veterinary*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005243:Feces / Q000382:microbiology; D008070:Lipopolysaccharides / Q000276:immunology; D012481:Salmonella Infections, Animal / Q000635:transmission*; D012486:Salmonella typhimurium / Q000276:immunology / Q000302:isolation & purification* / Q000472:pathogenicity; D013047:Specific Pathogen-Free Organisms; D013552:Swine; D013553:Swine Diseases / Q000382:microbiology / Q000635:transmission*
chemical_list: D000907:Antibodies, Bacterial; D008070:Lipopolysaccharides