Serologic survey of Neospora caninum infection in a closed dairy cattle herd in Maryland: risk of serologic reactivity by production groups

Prevalence of antibodies to Neospora caninum was determined in a cross-sect ional consensus survey of 1029 bovines in a dairy herd with endemic Neospor a-induced abortion. Sera were screened by indirect fluorescent antibody tes t (IFAT). The prevalence of N. caninum antibody in the IFAT was 17.9% in 10 7 neonates, 26.2% in 233 yearling heifers and steers, 39.07% in 218 mature heifers, and 26.9% in 465 milking cows. Serologic reactivity was associated with production grouping on the farm with the greatest risk of serologic r eactivity appearing in the yearling and mature heifers. There was an increa sing risk of serologic reactivity with increasing age only in the parity on e and greater animals in the herd. Castrated males were at half the risk of similarly aged females of possessing antibodies to N. caninum. There was n o clear relationship between the serologic status of dams and offspring. (C ) 2000 Elsevier Science B.V. All rights reserved.