Pro- und retrospektive Untersuchung zum Auftreten von Circovirus-assoziierten Erkrankungen beim Schwein in der Schweiz

• Forschungsstelle: BLV
• Projektnummer: 1.02.04
• Projekttitel Englisch: Pro- and retrospective investigation in circovirus-associated diseases in swine in Switzerland

Schlüsselwörter (Englisch)

PMWS, PCV2, diagnosis, incidence, pig health

Kurzbeschreibung (Englisch)

Porcine circovirus type 2 (PCV2) has now been associated, on a worldwide basis, with a variety of clinical manifestations. The most prominent disease complex in which the virus has been implicated is porcine multi-systemic wasting syndrome (PMWS). Clinical disease is characterized by progressive weight loss, tachypnoea, diarrhoea, and icterus in predominantly 8 - 12 week-old pigs. Consistent lesions include lymphoid depletion, granulomatous inflammation in lymphoid organs and lymphohistriocytic interstitial pneumonia. Less common are the lymphohistiocytic-to-granulomatous nephritis, hepatotis, interstitial pancreatitis, gastritis, enterocolitis, and segmental perivasculitis in a variety of organs. Macrophages within the inflammatory lesions may contain characteristic clusters of variably sized round basophilic inclusion bodies, composed of paracrystalline arrays of porcine circoviral type 2 (PCV 2) isocahedral virions. Wasting disease and lesions typical of PMWS could be reproduced in neonatal caesarian-derived and colostrum-deprived piglets inoculated with PCV 2, although disease symptoms were not of equal severity in all infected animals: the clinical disease and symptoms could be relatively mild or inconsistent in certain pigs. When the animals were co-infected with PCV2 and porcine parvovirus (PPV), severe PMWS was produced. It appeared that the co-infection enhanced replication of PCV 2. At least, it was the PCV2 which could be isolated from the symptomatic animals. Infection with PPV alone did not produce PMWS. Only when PCV2 was employed, was it possible to induce this disease, and infection of new animals with the isolated PCV2 reproduced PMWS, fulfilling Koch's Postulates.
The evidence is now clear that PCV2 is the causative agent of PMWS. Although the severity of the disease can be enhanced by co-infections with a second virus such as PPV, it is the PCV2 which is central to the PMWS development. Furthermore, infected animals which survive the PCV2 infection seroconvert, with the response being anti-PCV2.

During July and August 2000, PCV2-associated lesions were identified in samples from suspect cases of PMWS on 2 farms in Switzerland. In January 2001, cases with similar lesions were detected on a third farm. Consequently, the question arose concerning the extent of PCV2 infection in Switzerland, of particular im-portance considering the implication of this virus in a number of economically important diseases of pigs, not the least of which is PMWS.

Projektziele (Englisch)

The purpose of the project is
(i) to establish the application of the diagnostic tools for PCV2 using pro- and retrospectively collected samples from clinically diagnosed cases of PMWS and other disease entities in Switzerland,
(ii) to evaluate the incidence of PCV2 by retrospective study of post mortem cases with different case histories,
(iii) to compare retrospectively the data obtained with that from neighbouring countries - the relatively closed pig market in Switzerland will give important insight into the introduction of the disease.

Abstract (Deutsch)

Retrospektiv:
In den lymphatischen Organen von 39 der 496 untersuchten Schweine konnte immunhistochemisch PCV-2 nachgewiesen werden. Der erste positive Fall datiert aus dem Jahre 1986. Ab 1989 bis Mitte 2001 fanden sich jährlich 1-4 (1989-1997), respektive 5-8 (1998-2001) positive Tiere. Diese Resultate zeigen, dass PCV-2 bereits seit einiger Zeit in der Schweiz vorkommt, mindestens seit 1986.

Prospektiv:
Bei 11 Ferkeln aus 7 Betrieben konnte PCV-2 nachgewiesen werden, jedoch lediglich 4 Ferkel wiesen die für PMWS typischen histologischen Veränderungen in den lymphatischen Organen auf. Andere Kümmererursachen waren die Porzine Proliferative Enteropathie, Magenulzera, Polyserositis und Polyarthritis. Jedoch die meisten Ferkel litten an Durchfällen und chronischen Enteritiden unbekannter Ursache. Serologisch wiesen 70% der untersuchten Ferkel Antikörper gegen PCV-2 auf. Gemäss serologischer Untersuchung scheint PCV-2 in der Schweiz weit verbreitet zu sein. Hingegen konnte PMWS in den untersuchten Ferkeln selten gefunden werden.

Publikationen / Ergebnisse (Deutsch)

29.10.2009: Umsetzungssitzung 2009: VU gibt zu Bedenken, dass Circoviren momentan grosses Thema ist, 2 neue Circovirenprojekte sind in Planung. Resultate aus 1.02.04 sind nicht mehr topaktuell, inhaltlich ist das Projekt umgesetzt. Vorschlag UMS10: KOM schreibt zusammen mit IVI und Sydler einen Artikel mit der Vorankündigung für die beiden neuen Circoviren Projekten, die die Foko bewilligt hat. Neuer Status: „erledigt“ (mvo).

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• 1.02.04 Staebler [PDF] 248 kB

Publikationen / Ergebnisse (Englisch)

Staebler, S., Sydler, T., McCullough, K., Pospischil, A. (2002): Retrospektive immunhistochemical investigation of porcine circovirus type 2 in formalin fixed and paraffin-embedded swine tissues. In Proceedings of the 20th Meeting of the European Society of Veterinary Pathology: Page 179. Grugliasco (Turin) (+Poster)

Staebler, S., Sydler, T., Buergi, E., McCullough, K., McNeilly, F., Allan, G., Pospischil, A. (2004): PMWS: an emerging disease identified in archived porcine tissues. The Veterinary Journal, 170 (2005), 132-134.

Staebler, S., Buergi, E., Litzenberger, B., McCullough, K., McNair, I., McNeilly, F., Pospischil, A., Sydler, T. Porcine circovirus as a possible cause of post-weaning wasting in pigs in Switzerland. Schweiz. Arch. Tierheilk. Band 146, Heft 10, Oktober 2004, 461-469.

Staebler, Sandra, Tierärztin von Oberbüren SG (2004): Pro- and retrospective investigation of Circovirus-associated diseases in pigs in Switzerland. Dissertation Institut für Veterinärpathologie der Vetsuisse-Fakultät Universität Zürich, Schweiz.