ESTABLISHMENT OF A VOLUNTARY PROGRAM FOR THE CONTROL OF INFECTIOUS BOVINE-RHINOTRACHEITIS IN THE WALLOON REGION OF BELGIUM

From 1991 to 1994, a voluntary programme for the control of infectious bovine rhinotracheitis (IBR) was set up in 70 farms in the Walloon re gion of Belgium. The control of this viral infection caused by bovine herpesvirus 1 (BHV-1) was already carried out in several European coun tries or regions. Latency of this virus is the main difficulty to cope to control viral infection. A quick culling of BHV-1 seropositive ani mals is unfeasible in Walloon Region because the prevalence of seropos itive animals is about 60%. IBR control must be associated with repeat ed vaccinations of cattle and the use of strict hygienic measures to r educe virus circulation and afford clinical protection. Firstly, BHV-1 seroprevalence was assessed in the 70 farms and 47.2% among the 6153 tested animals were seropositive. Repeated vaccination programmes usin g inactivated vaccines were proposed and adjusted, taking account sero prevalence, previous vaccinations schemes, previous and recent clinica l outbreaks and farmer goals. The analysis of these data revealed circ ulation of virulent and hypovirulent BHV 1 strains and emphasized the fact that stopping IBR vaccination is highly dangerous. Beyond the use of technical measures, the study revealed that economic and human fac tors like the farmer goals and the willingness of the veterinary pract itioner cannot be neglected to successfully carry a BHV-1 control prog ramme.