Herd-level risk factors associated with Leptospira Hardjo seroprevalence in Beef/Suckler herds in the Republic of Ireland

Questionnaires were posted to 320 farmers chosen randomly from 6 regions, encompassing 25 counties, of the Republic of Ireland. The questionnaire was designed to obtain information about vaccination; reproductive disease; breeding herd details; the presence of recognized risk factors from previous studies; and husbandry on each farm. Data collected from 128 eligible herds were subjected to statistical analysis.Following the use of Pearson's Chi-Square Test, those variables associated with a herd being "infected" with a significance level of P < 0.2 were considered as candidates for multivariable logistic regression modelling. Breeding herd size was found to be a statistically significant risk factor after multivariable logistic regression. The odds of a herd being positive for leptospiral infection were 5.47 times higher (P = 0.032) in herds with 14 to 23 breeding animals compared with herds with ≤ 13 breeding animals, adjusting for Region, and 7.08 times higher (P = 0.033) in herds with 32.6 to 142 breeding animals.Breeding herd size was identified as a significant risk factor for leptospiral infection in Irish suckler herds, which was similar to findings of previous studies of leptospirosis in dairy herds.Leptospirosis, due to Leptospira Hardjo, is a disease of cattle worldwide [1-7]. In Ireland there are two species of leptospires that are associated with disease: Leptospira interrogans serovar Hardjo and Leptospira borgpetersenii serovar Hardjo. Collectively, both species can be referred to as Leptospira Hardjo. L. Hardjo mainly causes reproductive disease, i.e. abortion, mummification, stillbirth, premature and term birth of weak calves [8-11], as well as causing milk drop syndrome in dairy herds [12,13]. Leptospirosis is recognised as a significant zoonotic disease of farmers, farm workers and workers involved in the agricultural industry [14-19].Herd-level risk factors for leptospirosis due to L. Hardjo in dairy herds include: larger herd size; co-grazing wit