An outbreak of Infectious Bovine Rhinotracheitis (IBR) in a herd vaccinated with a live glycoprotein E deleted (marker) Bovine Herpes Virus-1 (BoHV-1) vaccine: lessons to be learned

Vaccines are commonly used in the control of bovine respiratory disease (BRD), however the field performance of these vaccines is poorly understood. We describe an outbreak of Infectious Bovine Rhinotracheitis (IBR) in a 383 animal beef finishing unit in Scotland, four months after vaccination with a live glycoprotein E deleted (marker) Bovine Herpes Virus-1 (BoHV-1) vaccine. Seroconversion to the vaccine was confirmed in acute sera, and seroconversion to field virus confirmed in convalescent sera. BoHV-1 was also identified in broncho-alveolar lavage fluid and conjunctival swabs using PCR. This outbreak highlights the importance of the reporting of veterinary vaccine Suspected Lack of Expected Efficacy (SLEE) events, as well as the paucity of data available to practitioners relating to the field performance of veterinary vaccines.