title: Seroprevalence of Toxoplasma gondii in mainland and sub-Antarctic New Zealand sea lion (Phocarctos hookeri) populations.
abstract: OBJECTIVE
  To investigate the seroprevalence of antibodies to Toxoplasma gondii in New Zealand sea lions (Phocarctos hookeri), as a potential contributor to reproductive failure.
  
  
  METHODS
  Archived sera were sourced from New Zealand sea lions from two recolonising mainland populations in the Otago Peninsula (n=15) and Stewart Island (n=12), as well as a declining population at Enderby Island (n=28) in the New Zealand sub-Antarctic. Sera were tested for antibodies to T. gondii using a commercially available ELISA (with samples considered positive if the sample to positive ratio was >30%), and latex agglutination test (LAT; with titres ≥1:32 considered positive). Western blot analysis was used to validate the results of a subset of 14 samples.
  
  
  RESULTS
  Five samples from sea lions in mainland locations were confirmed positive for antibodies to T. gondii. Two adult females exhibited high LAT antibody titres (min 1:2048, max 1:4096) on both occasions when sampled 1 and 2 years apart, respectively. No animals from Enderby Island were seropositive.
  
  
  CONCLUSIONS
  Toxoplasma gondii infection is unlikely to be a major contributor to poor reproductive success in New Zealand sea lions. However, continued surveillance is pertinent to assess subclinical and clinical impacts of the parasite on these threatened populations. The commercial tests evaluated here, with further species-specific threshold refinement could provide a fast, inexpensive and reliable indicator of T. gondii exposure in New Zealand sea lions.
authors.affiliation: a Wildbase, Institute of Veterinary, Animal and Biomedical Sciences , Massey University , Private Bag 11-222, Palmerston North 4442 , New Zealand.
authors.forename: S A
authors.initials: SA
authors.lastname: Michael
authors.affiliation: b Institute of Veterinary, Animal and Biomedical Sciences , Massey University , Private Bag 11-222, Palmerston North 4442 , New Zealand.
authors.forename: L
authors.initials: L
authors.lastname: Howe
authors.affiliation: c Marine Species and Threats, Department of Conservation , PO Box 10-420, Wellington , New Zealand.|d Current address: Wildbase, Institute of Veterinary, Animal and Biomedical Sciences, Massey University , Private Bag 11-222, Palmerston North 4442 , New Zealand.
authors.forename: B L
authors.initials: BL
authors.lastname: Chilvers
authors.affiliation: b Institute of Veterinary, Animal and Biomedical Sciences , Massey University , Private Bag 11-222, Palmerston North 4442 , New Zealand.
authors.forename: Pch
authors.initials: P
authors.lastname: Morel
authors.affiliation: b Institute of Veterinary, Animal and Biomedical Sciences , Massey University , Private Bag 11-222, Palmerston North 4442 , New Zealand.
authors.forename: W D
authors.initials: WD
authors.lastname: Roe
mesh_terms: D000818:Animals; D015153:Blotting, Western / Q000662:veterinary; D005260:Female; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D046070:Sea Lions / Q000469:parasitology*; D016036:Seroepidemiologic Studies; D014122:Toxoplasma; D014124:Toxoplasmosis, Animal / Q000453:epidemiology* / Q000469:parasitology
keywords: ELISA; Phocarctos hookeri; Toxoplasma gondii; latex agglutination test; pinniped; western blot