Infection with Ovine herpesvirus 2 in Norwegian herds with a history of previous outbreaks of malignant catarrhal fever.

Infection with Ovine herpesvirus 2 (OvHV-2) in healthy cattle, swine, sheep, and goats was investigated on 43 selected Norwegian farms; of which, 41 (95%) had experienced outbreaks of malignant catarrhal fever (MCF) in cattle and/or swine during the preceding 5 years. Two of the farms had no history of MCF and were included for control purposes. Blood samples from 384 cattle, 40 sows, 75 sheep, and 4 goats were examined for OvHV-2 by polymerase chain reaction assay (PCR) and for antibodies using a competitive inhibition enzyme-linked immunosorbent assay (ciELISA). All samples were also tested for antibodies reactive to Alcelaphine herpesvirus 1 with an indirect fluorescent antibody test (IFAT). All but 4 of the sheep and all 4 goats tested positive with 1 or more of the tests. Eighty-nine (25%) of the cattle and 17 (43%) of the swine on the farms with previous MCF outbreaks tested positive with 1 or more of the tests. On 22 of the farms, at least 1 bovine tested positive with ciELISA and/or PCR, whereas 8 other farms had test-positive cattle with IFAT only. The 2 control farms yielded no positive results with any of the tests. Four of the farms had swine that tested positive with PCR, but none with ciELISA, whereas 4 other farms had test-positive swine with IFAT only. The prevalence of infection in cattle and swine seemed not to be influenced either by their age or the degree of contact with the sheep and goats.