title: Efficacy of an avirulent live vaccine against Lawsonia intracellularis in the prevention of proliferative enteropathy in experimentally infected weanling foals.
abstract: OBJECTIVE
  To determine the efficacy of an avirulent Lawsonia intracellularis vaccine in preventing proliferative enteropathy in weanling foals.
  
  
  METHODS
  12 healthy weanling foals.
  
  
  METHODS
  Foals were randomly assigned to a vaccinated, nonvaccinated, or control group. Vaccinated foals received an avirulent porcine L intracellularis frozen-thawed vaccine intrarectally 60 and 30 days prior to experimental challenge. On day 1, vaccinated and nonvaccinated foals were challenged via nasogastric intubation with a virulent heterologous isolate of L intracellularis. Control foals were not challenged. Clinical observation and ultrasonographic evaluation of the small intestine were performed, and body weight, serum concentration of total solids, fecal excretion of L intracellularis, and seroconversion were measured for each foal until day 56. Diseased foals were treated with antimicrobials and supportive care.
  
  
  RESULTS
  None of the 4 vaccinated foals developed clinical disease following challenge with virulent L intracellularis. Three of 4 nonvaccinated foals developed moderate to severe clinical signs compatible with proliferative enteropathy, hypoproteinemia, and thickened small intestinal loops. Vaccinated foals had significantly less fecal shedding of L intracellularis than nonvaccinated foals. Serologic responses between vaccinated and nonvaccinated foals after challenge were similar. Control foals remained clinically unaffected with no evidence of fecal shedding and seroconversion.
  
  
  CONCLUSIONS
  Intrarectal administration of a commercial avirulent porcine vaccine against L intracellularis resulted in complete protection against proliferative enteropathy in the foals in this study and may also reduce environmental contamination with the organism on endemic farms.
authors.affiliation: Department of Veterinary Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA 95616, USA. npusterla@ucdavis.edu
authors.forename: Nicola
authors.initials: N
authors.lastname: Pusterla
authors.forename: Fabio A
authors.initials: FA
authors.lastname: Vannucci
authors.forename: Samantha M
authors.initials: SM
authors.lastname: Mapes
authors.forename: Nora
authors.initials: N
authors.lastname: Nogradi
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Collier
authors.forename: Jackie A
authors.initials: JA
authors.lastname: Hill
authors.forename: Melissa
authors.initials: M
authors.lastname: Difrancesco
authors.forename: Alexandria M
authors.initials: AM
authors.lastname: White
authors.forename: Nina K
authors.initials: NK
authors.lastname: Akana
authors.forename: Greg
authors.initials: G
authors.lastname: Simonek
authors.forename: Connie J
authors.initials: CJ
authors.lastname: Gebhart
mesh_terms: D000285:Administration, Rectal; D000818:Animals; D001428:Bacterial Vaccines / Q000008:administration & dosage / Q000276:immunology*; D045824:Desulfovibrionaceae Infections / Q000276:immunology / Q000662:veterinary*; D005243:Feces / Q000382:microbiology; D006734:Horse Diseases / Q000276:immunology* / Q000382:microbiology; D006736:Horses; D007150:Immunohistochemistry / Q000662:veterinary; D007410:Intestinal Diseases / Q000276:immunology / Q000473:pathology / Q000662:veterinary*; D007422:Intestines / Q000473:pathology / Q000503:physiopathology; D020639:Lawsonia Bacteria / Q000276:immunology*; D060888:Real-Time Polymerase Chain Reaction / Q000662:veterinary
chemical_list: D001428:Bacterial Vaccines