Om te komen tot een hogere gezondheidsstatus op de varkensbedrijven is kennis van belang. Kennis van de varkensziektes en hun verwekkers. Internationaal wordt er dan ook veel onderzoek gedaan. Een bloemlezing van recente resultaten door varkensdierenarts Robin Holle.
"Overleggen biggen <24 uur na geboorte ivm bestrijding Circo-infecties"
Overleggen biggen <24 uur na geboorte ivm bestrijding Circo-infecties
The objective of this study was to compare the immune status of two populations of piglets born of the same dams, half of them being weaned at 7 days of age and the other half at 28 days, by determining the immunoglobulin G (IgG) content and PCV2 antibody titers in colostrum and serum samples. The results show that early weaning had no effect on the immune status of piglets. Among the sows included in this study, two resulted negative for PCV2 antibodies, suggesting that within a naturally infected herd both PCV2 negative and positive sows and offsprings can coexist.
Moreover, the positive correlation observed between passive immunity levels at 48 hours of age and PCV2 antibody titers from 28 days of age is noteworthy since it underlines the importance of a proper and homogenous colostrum intake of the offspring for the control of PMWS. In order to limit the circulation of PCV2, piglets should take both the colostrum of their mother and that of the adoptive mother. As a consequence, adoptions should be done within the 24 hours of life of the piglets. (LE DIVIDICH J, CARIOLET R, BLANCHARD P, BLEUNVEN E, LE COZLER Y Journées Recherche Porcine, 38, 2006, 347-352)
Vaccineren tegen Parvo is van belang bij bestrijding Circo-infecties
Vaccination against parvovirus provides some protection against PCV2 infection: no significant difference in reproductive disorders was observed between vaccinated PCV2-infected sows and PCV2-non-infected sows. Moreover, piglets born of vaccinated PCV2-infected sows showed lower PCV2 titers. An inadequate parvovirus vaccination is thus a risk factor for PMWS. In addition, PCV2-infected newborn piglets should always have an intake of colostral PCV2-antibodies in order to minimize the risks of spread of PCV2 to non-infected piglets. In a context of PCV2 circulation, particular care should thus be taken when making adoptions. (GERARD C, Réussir Porc, 2006, 123, 42-45)
Four groups of two SPF sows were included in this study with the following characteristics:
- PCV2-negative non-vaccinated,
- PCV2-positive and vaccinated for parvovirus and erisypelas with two monovalent vaccines (A),
- PCV2-positive and vaccinated for parvovirus and erisypelas with one bivalent vaccine (B),
- PCV2-positive non-vaccinated.
SPF sows were previously inoculated by the oronasal and intrauterine routes so as to become PCV2-positive. The offspring was investigated for the development of PMWS. A strong protective effect of vaccination was observed regarding reproductive disorders in sows since the number of mummified and stillborn piglets was similar for vaccinated PCV2-infected sows and PCV2-negative control sows while it was higher for PCV2-infected non-vaccinated sows. No significant difference was noted between the two protocol of vaccination except for PCV2 titers in piglets which were a bit lower with the bivalent vaccine. Cross-fostering of piglets born of infected sows and deprived of colostrum resulted in the rapid horizontal transmission of PCV2. Among the 84 piglets born during the study, 16 of them developed PMWS. Among these PMWS-affected piglets, most of them were born of PCV2-infected non-vaccinated sows and had no passive immunity. Improper vaccination for parvovirus/erisypelas and cross-fostering piglets between sows with undetermined immune status for PCV2 are two risk factors for PMWS. (ROSE N, BLANCHARD P, CARIOLET R, AMENNA N, KERANFLEC’H A, OGER A, JESTIN A, MADEC F Journées Recherche Porcine, 38, 2006, 339-346)
Bevestiging rol PRRS-virus bij andere virale infecties
In case of viral infection, plasmacytoid dendritic cells (pDC) secrete large amounts of IFNα which triggers antiviral IFNγ secreting cells and thus takes part to the development of an efficient
immune response. Previous studies have shown that PRRSV infection is associated with very low amounts or even a lack of IFNα in the lungs and plasma of PRRS affected pigs. This study, consisting of in vitro and in vivo observations, confirms that PRRSV impairs the production of IFNα and shows that the lack of IFNα is not due to a decrease in the population of pDC but to an actual inactivation of these cells by PRRSV, which takes place without pDC being infected by PRRSV. Once inactivated by PRRSV (wild type virus or commercial modified live PRRS vaccine), pDC even fail to respond to a other stimulations (RNA and DNA viruses) exposing animals to the risks of other viral infections. (CALZADA-NOVA G, HUSMANN R, SCHNITZLEIN W, ZUCKERMANN F
American Association of Swine Veterinarians - Proceedings, 2006, 459-461)
Verspreiding PRRS-virus over 600 en 1200 meter aangetoond
Porcine Reproductive and Respiratory Syndrome (PRRS) was initially called the “mystery disease”. Once more, PRRS sticks to this appellation since the case reported in this paper leaves little room for doubt about an actual airborne transmission of PRRSV. It is noteworthy that, to date, airborne transmission of PRRSV was achieved only in few cases, on very short distances and in experimental conditions. This time, spread of PRRSV occurred under field conditions from a farrowing unit to two fattening units situated respectively at 600 and 1200 meters from the farrowing unit. (SANDRI GP, GIOVANARDI D, PESENTE P, SPERATI-RUFFONI L, PIEMONTI D
Società Italiana di Patologia ed Allevamento dei Suini - Proceedings, 2006, 263-267)
