title: Seroprevalence of Leptospira Hardjo in the Irish suckler cattle population.
abstract: BACKGROUND
  Prior to the present study, the seroprevalence of leptospirosis in Irish suckler herds was unknown. In this study, we describe the herd and animal-level prevalence of Leptospira Hardjo infection in the Irish suckler cattle population. For the purposes of the study, the 26 counties of the Republic of Ireland were divided into 6 regions from which a representative number of herds were selected. A herd was considered eligible for sampling if it was not vaccinating against leptospirosis and if it contained ≥ 9 breeding animals of beef breed ≥ 12 months of age. In total, 288 randomly selected herds were eligible for inclusion in the seroprevalence dataset analysis. Serological testing was carried out using a commercially available monoclonal antibody-capture ELISA, (sensitivity 100%; specificity 86.67%).
  
  
  RESULTS
  Herds were categorised as either "Free from Infection" or "Infected" using the epidemiological software tool, FreeCalc 2.0. Using this classification, 237 herds were "Infected" (82.29%). The South West and South East regions had the highest herd prevalence. The regional effect on herd prevalence was largely mirrored by breeding herd size. A true animal-level prevalence of 41.75% was calculated using the epidemiological software tool, TruePrev. There was a statistically significant regional trend, with true prevalence being highest in the South East (P < 0.05). The median Breeding Herd Size (BHS), when categorised into quartiles, had a statistically significant influence on individual animal true seroprevalence (P < 0.001); true seroprevalence increased with increasing BHS.
  
  
  CONCLUSIONS
  Leptospirosis is a widespread endemic disease in the Republic of Ireland. It is possible that economic losses due to leptospirosis in unvaccinated Irish suckler herds may be underestimated.
authors.affiliation: School of Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Republic of Ireland. eoin.g.ryan@ucd.ie.
authors.forename: Eoin Gerard
authors.initials: EG
authors.lastname: Ryan
authors.forename: Nola
authors.initials: N
authors.lastname: Leonard
authors.forename: Luke
authors.initials: L
authors.lastname: O'Grady
authors.forename: Simon J
authors.initials: SJ
authors.lastname: More
authors.forename: Michael L
authors.initials: ML
authors.lastname: Doherty