Bovine virus diarrhoea (BVD) control programme in an area in the Rome province (Italy)

A BVD control programme based on the identification and removal of persiste ntly infected (PI) animals is being undertaken in an area in the Pome provi nce, where BVD outbreaks had been previously detected. It involves 174 main ly dairy herds, from which blood samples of all bovines older than 1 year a re obtained through the national brucellosis and leukosis eradication progr amme. Samples sufficient to detect the presence of seropositive animals at a prevalence of 5% or more are initially screened for antibodies against BV D virus (BVDV) using an immunoenzymatic assay. Upon identification of seror eagents additional blood samples are tested from the 6-12-month age categor y not included in the initial samples. Animals are considered immunotoleran t if BVDV is demonstrated twice at a minimum 30-day interval. When no serop ositive animals are detected during the first serological screening the her d is declared BVD-free if a second testing, preferably carried on the same animals previously tested, confirms the seronegative status of the herd. At present 147 farms have been tested, of which 63 (42.9%) are negative with respect to antibodies against BVDV. Of the 84 remaining herds in which one or more seropositives are detected, 13 an classified as recently infected. In eight of these recently infected herds, 22 PI animals have been identifi ed. (C) 1999 Elsevier Science B.V. All rights reserved.