title: Seroprevalence of Neospora caninum infection following an abortion outbreak in a dairy cattle herd.
abstract: OBJECTIVE
  To investigate the seroprevalence of Neospora caninum infection in a commercial dairy cattle herd, 15 months after detection of an abortion outbreak.
  
  
  METHODS
  Sera from the whole herd (n = 266) were examined for N caninum antibodies by indirect fluorescent antibody test (IFAT) and immunoblot analysis. Herd records were reviewed to collate serological results with abortion history, proximity to calving, and pedigree data.
  
  
  RESULTS
  The seroprevalence of N caninum infection was 24% (63/266) for IFAT titre > or = 160, 29% (78/266) for immunoblot positive (+ve), and 31% (82/266) for IFAT > or = 160 and/or immunoblot +ve; 94% (59/63) of animals with IFAT > or = 160 were immunoblot +ve. The association between seropositivity (IFAT > or = 160 and/or immunoblot +ve) and history of abortion was highly significant (P < 0.001); the seroprevalence was 86% (18/21) in aborting cows, compared with 30% (50/164) in non-aborting animals. The abortion rate for seropositive cows was 26% (18/68) compared with 3% (3/117) for seronegative animals. IFAT titres of infected cows were higher within 2 months of calving than at other times (P < 0.001). The association between seropositivity in dams and daughters was highly significant (P = 0.009).
  
  
  CONCLUSIONS
  The abortions were associated with N caninum infection and there was evidence of reactivation of latent infection close to calving and congenital transmission of infection. Immunodominant antigens identified by immunoblots may prove useful for improved diagnostic tests.
authors.affiliation: Molecular Parasitology Unit, University of Technology, Sydney, New South Wales.
authors.forename: R A
authors.initials: RA
authors.lastname: Atkinson
authors.forename: R W
authors.initials: RW
authors.lastname: Cook
authors.forename: L A
authors.initials: LA
authors.lastname: Reddacliff
authors.forename: J
authors.initials: J
authors.lastname: Rothwell
authors.forename: K W
authors.initials: KW
authors.lastname: Broady
authors.forename: P
authors.initials: P
authors.lastname: Harper
authors.forename: J T
authors.initials: JT
authors.lastname: Ellis
mesh_terms: D000034:Abortion, Veterinary / Q000453:epidemiology / Q000469:parasitology; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000097:blood; D015153:Blotting, Western / Q000662:veterinary; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood / Q000453:epidemiology* / Q000469:parasitology; D003048:Coccidiosis / Q000453:epidemiology / Q000662:veterinary*; D003612:Dairying; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000662:veterinary; D015151:Immunoblotting / Q000662:veterinary; D018688:Neospora / Q000276:immunology* / Q000302:isolation & purification; D009517:New South Wales / Q000453:epidemiology; D011247:Pregnancy; D016036:Seroepidemiologic Studies
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan