PREVALENCE OF BOVINE PARVOVIRUS INFECTION IN ONTARIO DAIRY-CATTLE

Studies were conducted to determine prevalence and dynamics of bovine parvovirus (BPV) infection. Dairy cows from 29 randomly selected herds in southwestern. Ontario were tested twice, one year apart, for the p resence of hemagglutination inhibition (HI) antibodies against BPV. Fi fty-one percent of 1141 cows tested had BPV-HI titers >1:32. One year later, the seroprevalence was 83% in 1131 cows from the same farms. Th e herd mean seroprevalence was 49% and 86% for the year-1 and year-2 s amples, respectively. Evidence of BPV infection was found in 96% (27/2 8) of herds in year-1 and 100% of herds in year-2. A comparison of tit ers from 716 cows tested twice showed evidence of frequent BPV infecti on. Sixty-two percent of 326 animals selected in a systematic manner f rom 40 Guelph area dairy farms had BPV-HI titers >1:32. The herd mean seroprevalence was 64% Two herds had no animals with titers above the critical titer (1:32) while in one-quarter of the herds all animals ex ceeded the critical titer.