Six-Year Follow-up of Slaughterhouse Surveillance (2008-2013): The Catalan Slaughterhouse Support Network (SESC).

Meat inspection has the ultimate objective of declaring the meat and offal obtained from carcasses of slaughtered animals fit or unfit for human consumption. This safeguards the health of consumers by ensuring that the food coming from these establishments poses no risk to public health. Concomitantly, it contributes to animal disease surveillance. The Catalan Public Health Protection Agency (Generalitat de Catalunya) identified the need to provide its meat inspectors with a support structure to improve diagnostic capacity: the Slaughterhouse Support Network (SESC). The main goal of the SESC was to offer continuing education to meat inspectors to improve the diagnostic capacity for lesions observed in slaughterhouses. With this aim, a web-based application was designed that allowed meat inspectors to submit their inquiries, images of the lesions, and samples for laboratory analysis. This commentary reviews the cases from the first 6 years of SESC operation (2008-2013). The program not only provides continuing education to inspectors but also contributes to the collection of useful information on animal health and welfare. Therefore, SESC complements animal disease surveillance programs, such as those for tuberculosis, bovine cysticercosis, and porcine trichinellosis, and is a powerful tool for early detection of emerging animal diseases and zoonoses.

Outbreak of mortality in psittacine birds in a mixed-species aviary associated with Erysipelothrix rhusiopathiae infection.

Erysipelothrix rhusiopathiae septicemia, associated with an increased mortality of captive psittacines in a mixed-species aviary, was diagnosed by histopathology, Gram staining, bacterial culture and sequencing, immunohistochemistry, and real-time polymerase chain reaction (PCR). Over a period of 23 days with no premonitory signs, 2 rainbow lorikeets and an eclectus parrot died. Of these birds, one lorikeet and the eclectus were submitted for necropsy. The main pathologic findings were thrombosis (2/2), bacterial embolism/thromboembolism (2/2), necrotizing hepatitis (2/2), necrohemorrhagic myocarditis (1/2), fibrinohemorrhagic and heterophilic visceral coelomitis (1/2), submandibular necrosuppurative dermatitis with necrotizing vasculitis and bacterial and fungal thromboembolism (1/2), and locally extensive rhabdomyonecrosis with bacterial embolism (1/2). Intralesional bacteria were positive by Gram staining and immunohistochemistry in both cases. E. rhusiopathiae was isolated by routine bacterial culture from the liver of the lorikeet, which was also positive by real-time PCR. This report is one of the rare descriptions of erysipelas in psittacines, and to the authors' knowledge, it appears to be the first in the described species using immunohistochemistry and real-time PCR on avian paraffin-embedded tissues for the diagnosis.

A case of feline gastrointestinal eosinophilic sclerosing fibroplasia associated with phycomycetes.

Feline gastrointestinal eosinophilic sclerosing fibroplasia (FGESF) is a recently described inflammatory condition of domestic cats with unknown aetiology. A proportion of cases of FGESF are associated with bacteria, but antibiotic treatment is ineffective. It has been hypothesized that genetically predisposed cats may develop FGESF in response to the introduction of bacteria or other antigens into the intestinal wall. A 9- month-old male Persian cat presented with a history of marked acute haematemesis. A mass (10 cm diameter) was detected within the pylorus and proximal duodenum and this was not surgically accessible. On necropsy examination the duodenal wall was seen to be markedly thickened with extensive mucosal ulceration. Microscopically, there were haphazardly oriented trabecular bands of dense eosinophilic collagen, separated by wide, clear areas containing variable numbers of fibroblasts, eosinophils, mast cells, neutrophils, macrophages, lymphocytes and plasma cells. Numerous pleomorphic, non-parallel walled, sparsely septate hyphae, characteristic of phycomycetes, were present within the collagen matrix. Colonies of gram-positive and gram-negative rods were also present within the lesion. This is the first description of FGESF with intralesional fungi.

Simultaneous porcine circovirus type 2 and Mycoplasma hyopneumoniae co-inoculation does not potentiate disease in conventional pigs.

The aim of this study was to assess the effect of simultaneous experimental inoculation of porcine circovirus type 2 (PCV2; intranasal delivery) and Mycoplasma hyopneumoniae (Mhyo; transtracheal delivery) into conventional, seropositive 6-week-old piglets. Thirty-six male piglets were assigned randomly to four groups: control (n=6), PCV2 (n=6), Mhyo (n=12) and PCV2+Mhyo (n=12). Blood samples and faecal and nasal swabs were collected at 0, 7, 14 and 21 days post inoculation (dpi). No significant clinical signs attributable to PCV2 infection were observed during the experiment. Coughing was recorded in three pigs from the Mhyo group and six from the PCV2+Mhyo group. No significant differences in mean body weight and rectal temperature were observed between the groups. Mild microscopical lesions similar to those reported for post-weaning multisystemic wasting syndrome were observed in two PCV2 pigs and in one PCV2+Mhyo animal. Mhyo-compatible lung lesions were observed in 21/24 pigs inoculated with Mhyo (10 from the Mhyo group and 11 from the PCV2+Mhyo group). PCV2 was detected by in-situ hybridization in 3/12 PCV2 and in 4/12 PCV2+Mhyo animals. No significant differences in PCV2 load (serum and nasal and faecal swabs), duration of viraemia or antibody titre were detected between PCV2-inoculated groups. No significant differences in Mhyo load in nasal swabs, percentage of Mhyo-seropositive pigs and mean lung score was detected between Mhyo-inoculated groups. Under the conditions of the present study, concurrent inoculation of PCV2 and Mhyo did not result in potentiation of clinical signs and lesions attributed to either infection.

Lymphoplasmacytic endotheliitis and anterior uveitis in sheep infected experimentally with rift valley fever virus.

Lymphoplasmacytic endotheliitis and anterior uveitis was diagnosed in four lambs infected experimentally with field isolates of Rift Valley fever virus (RVFV). Formalin-fixed and paraffin wax-embedded tissue from these animals was investigated by histopathology and quantitative real time reverse transcriptase polymerase chain reaction. To our knowledge, this is the first pathological description of this ocular manifestation of RVFV infection in ruminants, although these lesions have been described in man.

Effects of challenge with a virulent genotype II strain of porcine reproductive and respiratory syndrome virus on piglets vaccinated with an attenuated genotype I strain vaccine.

Porcine reproductive and respiratory syndrome virus (PRRSV) is endemic in most parts of Asia, where genotype I and II strains of diverse virulence may coexist. This study evaluated the outcome of infection with a highly virulent Asian genotype II PRRSV isolate in piglets vaccinated with a genotype I vaccine. Twenty-one 3-week-old piglets were divided in three groups: Pigs in group V (n=8) were vaccinated with an attenuated genotype I commercial PRRSV vaccine, while pigs in group U (n=8) and a control group (group C; n=5) were unvaccinated; 6 weeks later, pigs in groups V and U were challenged intranasally with a highly virulent strain of genotype II PRRSV (1×10(5) 50% tissue culture infectious doses/mL), while pigs in group C received a placebo. Over a period of 21 days after challenge, vaccinated pigs had significantly lower mortality (0/8 versus 2/8), fewer days of fever, a lower frequency of catarrhal bronchopneumonia, higher weight gains (13.4 versus 6.6 kg) and lower levels of viraemia compared to unvaccinated challenged pigs. Immunisation with a genotype I attenuated PRRSV vaccine provided partial protection against challenge with a highly virulent genotype II strain.

Characterization of necrotizing lymphadenitis associated with porcine circovirus type 2 infection.

Necrotizing lymphadenitis is observed in approximately 2% of pigs affected by post-weaning multisystemic wasting syndrome (PMWS). The pathogenesis of the lesion has been linked to apoptosis induced by porcine circovirus type 2 (PCV2). The aim of the present study was to gain further insights into PCV2-associated lymphoid necrosis in pigs with PMWS. Three groups of animals were studied: (1) PMWS-affected pigs with necrotizing lymphadenitis (n=5), (2) PMWS-affected pigs without necrotizing lymphadenitis (n=5) and (3) healthy pigs with no PMWS-related lesions (n=5). Investigations performed included immunohistochemical evaluation of the expression of cleaved caspase-3 and von Willebrand factor, Mallory's staining for fibrin and in-situ hybridization for detection of the PCV2 genome. The results of the study suggested that lymphoid necrosis in PMWS-affected pigs may be related to hypertrophy and hyperplasia of high endothelial venules (HEVs). The mechanism underlying these changes in HEVs was not clearly defined, but necrotizing lymphadenitis in pigs with PMWS may develop following vascular damage with thrombosis and subsequent follicular necrosis. Apoptosis was not found to be involved in lymphocyte depletion in PMWS or in PMWS-associated necrotizing lymphadenitis.

Novel group A rotavirus G8 P[1] as primary cause of an ovine diarrheic syndrome outbreak in weaned lambs.

Rotavirus is a worldwide major cause of diarrhea outbreaks in neonatal ruminants. An outbreak of ovine diarrheic syndrome (ODS) in 50-75 days-old lambs (weaned lambs) is described. Fecal immunochromatography and intestinal immunohistochemistry for rotavirus group A were performed. In addition, semi-nested multiplex RT-PCR for G and P rotavirus genotyping in combination with sequencing were performed, to support the diagnosis and identify the viral strain. A novel ovine rotavirus group A G8 P[1] strain was determined as the main cause of the ODS observed, whereas other pathogens were ruled out.

Intranuclear detection of African swine fever virus DNA in several cell types from formalin-fixed and paraffin-embedded tissues using a new in situ hybridisation protocol.

In this study, a new in situ hybridisation (ISH) protocol has been developed to identify African swine fever virus (ASFV) genome in formalin-fixed, paraffin-embedded tissues. Different digoxigenin labelled ASFV-probes were tested, including single ASFV-specific oligonucleotides, an 18.5kb restriction fragment from the viral genome and the entire ASFV genome. The latter showed the highest sensitivity in all tissues tested, independently of the virus used for challenge: E75L or Ba71L. Although a similar ASFV genome distribution was observed, the number of ISH-positive cells was higher for Ba71L compared to E75L infected tissues. As expected, the monocyte-macrophage cell lineage was the main target cell for ASFV infection. Corresponding with the last stages of infection, ISH-positive signals were also found in other cell types, including endothelial cells, hepatocytes and neutrophils. Furthermore, two unexpected findings were also noticed: the detection of a specific ISH-signal in lymphocytes and a tendency to find the signal in the nucleus of infected cells. In summary, the present findings demonstrate the utility of this new ISH protocol to study ASFV pathogenesis and its potential use as a diagnostic tool.