Rola szczepien szczepionkami delecyjnymi w ograniczaniu rozprzestrzeniania wirusa choroby Aujeszkyego w fermach swin objetych programem "szczepienie - eliminacja"

Vaccinations play an important role in the control of Aujeszky’s disease (AD) because they interrupt the chain of piglet morbidity and mortality as well as decreasing the spread of Herpesvirus suis type 1 (SHV-1). Conventional vaccines, however, preclude serological differentiation between vaccinated and SHV-1 infected pigs. Such differentiation has only become possible after the creation of deleted (marker) vaccines, which, together with the appropriate serological tests (ELISA), have enabled the realisation of a „vaccination - eradication programme” and presented a new perspective on AD eradication in those countries where pigs are vaccinated. The purpose of this study was to evaluate the influence of an intensive vaccination programme using deleted vaccine in decreasing the spread of SHV-1 in two highly infected pig farms covered in the „vaccination - eradication programme”. All the pigs were vaccinated with deleted, gE- and TK-negative, live attenuated Nobi - Porvac Aujeszky Live Begonia (at present Porcilis Begonia) vaccine - Intervet Int. Holland according to its accepted programme: reproductive pigs 4 months apart and fattening pigs twice at 10-12 and 14-16 week of age. Control serological examinations with gE-ELISA using CHEKIT-PRV-gl-EIA, dr Bommeli AG, Switzerland were performed. In groups of sows a gradual, slow decrease of SHV-1 infection rates from 100% before vaccination to 60% in farm R and 41.7% in farm В after the 4th re-vaccination were observed. A more rapid decrease of SHV-1 infection rates among fattening pigs - from 90% to 10% after 13 months and 0% after the 19 month of herd vaccinations in farm R, and from 80% to 0% as early as after 7 months of herd vaccination in farm В were observed. Serological examinations of all sows and boars after 2.5 years of herd vaccination revealed a decrease of SHV-1 infection rates from 100% to 34,9% in farm R and 28.2% in farm В respectively. This demonstrated that appropriately prepared and consequently realised vaccination programmes of all pigs, using a good quality deleted vaccine, radically decreases the spread of virulent SHV-1 virus in infected herds. The possibilities of serological differentiation between immunised and infected pigs combined with a natural rotation of infected reproductive pigs and, next, with an appropriate and properly conducted, economically viable elimination of seropositives creates a realistic chance of eliminating virulent SHV-1 even from highly infected swine herds.