title: The blurred border between porcine circovirus type 2-systemic disease and porcine respiratory disease complex.
abstract: Porcine respiratory disease complex (PRDC) is the name used to describe a clinical presentation characterized by respiratory signs and poor growth in growing-finishing pigs. Porcine circovirus type 2 (PCV2) is one of the pathogens potentially involved in the presentation of this complex, although, it has been mainly linked to PCV2-systemic disease (PCV2-SD). However, some reports have suggested that PCV2 can cause respiratory lesions in the absence of systemic lymphoid damage; this apparently different condition has been referred as PCV2-lung disease (PCV2-LD). The present study analysed retrospectively the relation between PRDC and PCV2 infection from a pathological point of view. Of the 317 selected pigs suffering from PRDC and submitted for necropsy between 1998 and 2011, the most prevalent lesions were subacute interstitial pneumonia (27.7%) and the combination of subacute interstitial pneumonia plus catarrhal-purulent bronchopneumonia (28.4%). Two hundred and twenty-six pigs were positive for PCV2 by in situ hybridization (ISH); using immunohistochemical techniques, 77 were positive for porcine reproductive and respiratory syndrome virus and 3 for swine influenza virus. Among positive pigs for PCV2 ISH, 184 animals suffered from PCV2-SD. The rest of 42 PCV2 ISH positive pigs had no lymphoid lesions and low amount of viral nucleic acid in these tissues and, therefore, did not qualify for PCVD-SD; only 9 had concomitant PCV2 ISH positivity in the lung, also to a low amount. In conclusion, all PRDC-PCV2 ISH positive cases had evidence of viral systemic infection. These results suggest that PCV2-LD is probably a negligible condition and PCV2 mainly contributes to PRDC in relation to PCV2-SD occurrence.
authors: Departament de Sanitat i Anatomia Animals, Facultat de Veterinària, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain.
authors: G
authors: G
authors: Ticó
authors: J
authors: J
authors: Segalés
authors: J
authors: J
authors: Martínez
mesh_terms: D000818:Animals; D018173:Circoviridae Infections / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D017925:Circovirus / Q000235:genetics / Q000502:physiology*; D004279:DNA, Viral / Q000032:analysis; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008168:Lung / Q000473:pathology / Q000821:virology; D008221:Lymphoid Tissue / Q000473:pathology; D015995:Prevalence; D012140:Respiratory Tract Diseases / Q000150:complications / Q000175:diagnosis / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D012189:Retrospective Studies; D013030:Spain / Q000453:epidemiology; D013552:Swine; D013553:Swine Diseases / Q000175:diagnosis* / Q000453:epidemiology / Q000473:pathology / Q000821:virology
chemical_list: D004279:DNA, Viral