title: Serosurvey of leptospirosis and investigation of a possible novel serovar Arborea in farmed deer in New Zealand.
abstract: OBJECTIVE
  To investigate the prevalence of Leptospira spp. and possible novel serovar Arborea infection in farmed deer in New Zealand.
  
  
  METHODS
  In September 2006, five serum samples from a serum bank from each of 70 farms sampled for a previous national prevalence survey were forwarded to the World Health Organisation/Food and Agriculture Organisation/World Organisation for Animal Health (WHO/FAO/OIE) reference laboratory for leptospirosis in Brisbane, Australia, to test for reactivity to a reference panel of 23 serovars, most believed to be exotic to New Zealand, using the microscopic agglutination test (MAT). Eleven farms were seropositive for Arborea, a serovar novel to New Zealand. In July 2007, 126 additional banked serum samples from nine of those 11 farms (n=8-20/farm) were sent to the reference laboratory for similar serology. Two farms in the Southland region were considered positive for serovar Arborea. Tissue from deer kidneys (n=43) from these two farms collected at a deer slaughter premises (DSP) was cultured in November 2007 and November 2008. Sera from those deer were also sent to the laboratory in Brisbane.
  
  
  RESULTS
  From the initial 350 sera, 96 (27.4%) and 19 (5.4%) samples were positive for Leptospira borgpetersenii serovar Hardjo-bovis and Leptospira interrogans serovar Pomona respectively. There were cross-reactions between serovar Hardjo-bovis with serovars Medanensis and Szwajizak. Serological evidence of serovars Tarassovi, Grippotyphosa, Celledoni, Australis, Zanoni, Robinsoni, Canicola, Kremastos, Bulgarica, Cynopteri, Ballum, Bataviae, Djasiman, Javanica, Panama, Shermani and Topaz was negative or sporadic, generally with titres of 1:50 and therefore likely non-specific. Fourteen (4.0%) samples from 11 farms were positive for serovar Arborea, justifying further investigation. The prevalence of serovar Arborea was 15% and 30% on two farms, from the 126 samples. None of 43 kidney and serum samples collected subsequently from those two farms were positive by culture or serology for serovar Arborea.
  
  
  CONCLUSIONS
  While there were samples serologically positive for serovar Arborea in deer, attempts to isolate the organism were unsuccessful. The sample size for the follow-up investigation was insufficient to validate the presence or absence of infection, so further study should be undertaken to verify the status of this serovar of Leptospira spp. in New Zealand, in both deer and other livestock species.
authors.affiliation: Institute of Veterinary, Animal and Biomedical Sciences, Massey University, Private Bag 11222, Palmerston North, New Zealand. art.subharat@agresearch.co.nz
authors.forename: S
authors.initials: S
authors.lastname: Subharat
authors.forename: P R
authors.initials: PR
authors.lastname: Wilson
authors.forename: C
authors.initials: C
authors.lastname: Heuer
authors.forename: J M
authors.initials: JM
authors.lastname: Collins-Emerson
authors.forename: L D
authors.initials: LD
authors.lastname: Smythe
authors.forename: M F
authors.initials: MF
authors.lastname: Dohnt
authors.forename: S B
authors.initials: SB
authors.lastname: Craig
authors.forename: M A
authors.initials: MA
authors.lastname: Burns
mesh_terms: D000818:Animals; D000829:Animals, Domestic; D000907:Antibodies, Bacterial / Q000097:blood; D003429:Cross Reactions; D003670:Deer; D007919:Leptospira / Q000145:classification* / Q000276:immunology / Q000302:isolation & purification; D007922:Leptospirosis / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D009520:New Zealand / Q000453:epidemiology; D016036:Seroepidemiologic Studies
chemical_list: D000907:Antibodies, Bacterial