An evaluation of the prevalence of Bovine herpesvirus 1 abortions based on diagnostic submissions to five U.S.-based veterinary diagnostic laboratories.

Bovine herpesvirus 1 (BoHV-1) is 1 of several viruses considered to be causal agents of bovine abortion. The current retrospective study examined data on bovine abortion submissions from 5 veterinary diagnostic laboratories from 2000 to 2011. The objective of the study was to describe prevalence of BoHV-1-associated abortion in submissions at veterinary diagnostic laboratories. There were 3 specific aims: 1) to examine the proportion of BoHV-1-related abortions with the introduction of new diagnostic assays such as polymerase chain reaction (PCR), 2) to evaluate the agreement of the histopathology report of the abortion submissions and the result of the assay used, and 3) to evaluate if there was an association between farm history of vaccination against BoHV-1 and BoHV-1-positive abortion submissions. An extended Mantel-Haenszel χ(2) for linear trend was used to analyze the prevalence of BoHV-1 over the study period and showed that collectively there is evidence of an increase of positive BoHV-1 abortions (P < 0.001). The comparison of the proportion of BoHV-1-positive submissions pre- and postadoption of PCR was not significant (P = 0.25). Using Cohen kappa coefficient test of agreement, a kappa value of 0.81 (P < 0.001) was found, suggesting high agreement of lesions reported and assay result. It was found that using a χ(2) test, a P value of 0.068 for nonmatched data (i.e., a history of vaccination against BoHV-1 in the herd) was associated with reduced detection of BoHV-1-positive abortion submissions.