Herd-level risk factors associated with Leptospira spp. seroprevalence in dairy and beef cattle in Spain.

Our aim in this cross-sectional study was to investigate the seroprevalence of Leptospira spp. infection in herds and cattle and the relationships between seroprevalence and beef versus dairy, size, replacement policy and grazing management in a representative area of beef- and dairy-cattle production in Spain. Herds were the initial sampling unit. Blood samples were collected from 762 dairy cattle belonging to 81 herds and 1238 beef cattle from 134 herds; sera were tested for antibodies against 11 serovars of Leptospira (autumnalis, ballum, bratislava, canicola, castellonis, copenhagheni, grippotyphosa, hardjo, louisiana, pomona and tarassovi) using the microagglutination test. Forty-three percent (36.2-49.5%) of the herds and 8% (6.4-8.8%) of the individuals were seropositive against one or more of the serovars studied. Bratislava was the most-prevalent serovar (24% of the herds and 4% of the individuals) followed by hardjo (11 and 1%, respectively). Grippotyphosa, copenhagheni and tarassovi were more prevalent in dairy than in beef herds (P<0.001, P<0.05, P<0.05, respectively) -- but no significant association was found between herd-size and Leptospira seroprevalence for any of the serovars considered.