Analysis of symptoms of disease after a BHV1 vaccination

Between 1 May 1998 and 22 February 1999, it was compulsory for Dutch cattle farmers to take measures against bovine herpesvirus 1 (BHV1). Cattle on fa rms that were not certified as infectious bovine rhinotracheitis (TBR)-free had to be vaccinated twice a year. During the vaccination programme, both farmers and veterinarians reported side-effects of the vaccine. These repor ts were collected by the Stichting IBR/BVD Schade (SIS; Foundation for IBR/ BVD Damage) in order to draw up a damage report. In 1999 in total 6977 catt le farmers lodged complaints which they considered to be related to the vac cination against BHV1. On these farms, 15,150 herd vaccinations had been pe rformed, 10,269 of which were associated with one or more symptoms. During the compulsory vaccination period, 13% of the herd vaccinations led to symp toms and complaints. In March 1999, a number of vaccine batches were found to be contaminated with bovine virus diarrhoea (BVD) virus. For the purpose s of this analysis, a 'known contaminated' herd vaccination was defined as one in which at least one 'known contaminated' batch or lot of vaccine was used. In total, 987 of 1007 herds vaccinated with 'known contaminated' vacc ines developed one or more symptoms compatible with acute BVD. There were no commonly seen combinations of symptoms. For this reason, and because the start and end dates were not reported for 55% of the symptoms, it was not possible to detect a symptom pattern. Therefore there were no 's uspect' batches of vaccine which, although not contaminated with BVD virus, gave rise to symptoms. The number of BVD symptoms was determined for those herds with vaccination-related symptoms. There was no difference in the di stribution frequency between batch numbers or between 'known contaminated' batches and 'non-suspect' batches. The farmers definition of chronic wasting was used in this investigation, w ith the inevitable large differences in definition. The symptom chronic 'wa sting' was reported for 3209 of the 10,269 herds with vaccination-related s ymptoms. On 161 farms (164 herd vaccinations) 'chronic wasting' was reporte d more often on farms where a 'known contaminated' vaccine was used. Inacti vated vaccine was used for 154 herd vaccinations. In 34 cases, one or more symptoms of acute BVD were reported. The frequency was the same as that for live vaccines. The frequency of reported symptoms tended to be lower with the inactivated vaccine. On the basis of the SIS data, no relationship was found between vaccine bat ch and reported symptoms. This may be because (i) the classification of a v accine as 'known contaminated', 'non-suspect', and 'not known' may not have been in keeping with the real status of the vaccine, (ii) farmers may have reported symptoms selectively, and (iii) there is no relationship with vac cination against BHV1.