[An outbreak of porcine reproductive and respiratory syndrome at a commercial pig complex]
2007
Kurinnov, V.V. | Bunkova, N.I. | Balashova, E.A. | Tsybanov, S.Zh. | Zelentsov, V.A.,All-Russia Research and Development Inst. of Veterinary Virology and Microbiology, Pokrov (Russian Federation)
The role of porcine reproductive and respiratory syndrome (PRRS) virus in the etiology of massive abortions was studied at one of the pig complexes after introducing into the main herd some replacement pigs Hypur imported from Poland and seronegative for viruses of PRRS, Aujeszkij disease, transmissible gastroenteritis, Teschen disease and porcine parvoviruses. An increase in the incidence of abortions among its own and newly inseminated sows (Hypur) depended on the pregnancy stage, however, in the periods of their maximal increase, above 50%, was observed at the end of the trimester. The PRRS virus of the European variant was isolated with reference of the results of serological [EIA (PRRS-SEROTEST) and indirect immunofluorescence test (IFT)], virological (RT-PCR) and postmortem studies giving reasons to suggest it circulates among sows and boars in spite of the regular vaccination with the emulsified inactivated vaccine against PRRS (strain BD of the American variant) and porcine parvovirus infection. The infection with PRRS virus of seronegative pigs from Poland resulted in a change in its pathogenicity (hemorrhagic inflammation of navel strings in aborted fetuses at days 105-111 of pregnancy),in consequence of which the population immunity (by EIA and IFT – not above 50%) did not inhibit the transfer of the virus from a sow to sow. It is concluded, that a continuous epizootological monitoring at the pig complex, the compliance of the vaccines with the pathogenesis of diseases, the optimization of feeding and keeping conditions, as well as observing the All in, all out principle are required.
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