Porcine circovirus type 2 associated reproductive failure in a specific pathogen free (SPF) piglet producing herd in Norway: a case report

Abstract

BackgroundSince 1999, scientists have published evidence of transplacental infection by porcine circovirus type 2 (PCV2) and reproductive failure in pigs. Affected herds have frequently been start-up herds, either naïve or with a high proportion of PCV2 susceptible gilts. Here, delayed farrowing in non-vaccinated gilts was observed in a commercial specific pathogen free (SPF) herd. Mummified fetuses and stillborn piglets recovered from these gilts were PCV2 positive.Case presentationThe case herd was a self-recruiting, piglet producing unit of 240 sows. After detecting livestock associated methicillin resistant Staphylococcus aureus (LA-MRSA, CC398), stamping out was imposed by the authorities. An SPF herd was re-established and all dams were vaccinated against PCV2 until the farmer decided to exclude this vaccine. The first non-vaccinated batch consisted of 76% gilts. Here, one gilt showed signs of impending farrowing. This gilt was slaughtered three to four weeks after the expected farrowing date without having expelled any uterine contents. In the subsequent batch consisting of 79% gilts, three gilts showed similar clinical signs. Delayed farrowing was observed in two of these gilts and the uterine contents from the third gilt were recovered at the abattoir. Mummified fetuses and stillborn piglets were recovered from all three gilts. High levels of PCV2 DNA (>107 viral genomic copies/ 500 ng tissue) were found in myocardial samples by real-time PCR analysis. One myocardial sample submitted for immunohistochemical (IHC) analysis showed moderate amounts of PCV2 antigen. In the subsequent batch consisting of 77% gilts, several weak-born piglets were seen across different litters.ConclusionsThis case report describes an apparent link between in utero PCV2 infection, pre partum nest-building behaviour, mammary development and delayed farrowing. To date, no reports have described imminent signs of farrowing and delayed farrowing as clinical signs in conjunction with transplacental PCV2 infection in Norway. Reinitiation of PCV2 vaccination was strongly advised in this herd due to recent depopulation and repopulation and the high proportion of gilts. Vaccination was effective because no further cases have occurred since.

Histological Lesions and Replication Sites of PCV3 in Naturally Infected Pigs

“…Within these 10 cases, nine were positive for PCV3 by ISH-RNA. This tropism of PCV3 to cardiac tissues has not been reported for PCV2 in pigs, except in fetus and stillborn piglets [ 25 ], but is a common finding in naturally PCV3-infected pigs from the present study and in experimentally PCV3-infected pigs [ 11 , 19 ], which reinforces some distinction on the tissue tropism between PCV3 and PCV2.…”

Viral DNA genomes in sera of farrowing sows with or without stillbirths

“…Such condition is considered a multifactorial problem [4]; on occasions, stillbirths have been associated to a number of known pathogens, including bacteria, protozoa, and viruses. Among viruses, those which have been most often associated with stillbirths are porcine parvovirus (ungulate protoparvovirus 1, UPV1) [5], porcine circovirus type 2 (PCV2) [6], Aujeszky's disease virus (ADV), Influenza virus [7], porcine reproductive and respiratory syndrome virus (PRRSV) [8], encephalomyocarditis virus (EMCV) [9] and classical swine fever virus (CSFV) [10]. Nevertheless, frequently, no viruses or other known pathogens seem to play a role in such condition [1,2,11,12].…”

WITHDRAWN: Identification of Porcine circovirus type (PCV2) and type 3 (PCV3), Porcine 2 parvovirus (PPV) in swine by multiplex PCR test

“…The virus was first identified in western Canada in a case of wasting disease using electron microscopy, immunohistochemical, and in situ hybridization methods [5]. Later,multipleother publications confirmed the circulation and the pathogenesis of PCV2 in swine abortions, and births of weak piglets [7,8,9,10]. PCV3 was recently described in a case of PDNS syndrome in a sow farm in North Carolina (USA) [1].…”