First Report of Brucella Seroprevalence in Wild Boar Population in Serbia.

Brucellosis is one of the most important bacterial zoonotic diseases worldwide, characterized in domestic animals by long-term reproductive disorders. As known, wild boars (Sus scrofa) are natural hosts for Brucella suis biovar 2, in which the infection passes in inapparent form, increasing the pathogen transmission risk to domestic pigs, other domestic animals and humans. So far, no studies regarding brucellosis in wild boars in Serbia have been published. During the hunting season 2020/2021, 480 sera of wild boars living in Serbia were collected and tested for the presence of anti-Brucella antibodies. For the serological survey, the Rose Bengal Test (RBT) and competitive enzyme-linked immunosorbent assay (c-ELISA) were used. Of the 480 sera, 45 sera tested positive, indicating the acquired Brucella seroprevalence in wild boars of 9.4%. The greatest numbers of Brucella seropositive animals were detected in the eastern parts of the country and in one of the central districts, i.e., Pomoravski, Branicevski, Borski and Juznobanatski. This study provides the first data regarding brucellosis in the wild boar population in Serbia, revealing the seroprevalence of Brucella, thus indicating that wild boars as natural hosts and/or vectors of Brucella likely present a risk for the infection of other animals.

Investigation of possible aetiological/triggering factors in porcine ear necrosis syndrome at a farrow-to-feeder pig system.

At a commercial farrow-to-feeder pig system with 2,100 sows in Serbia, lesions resembling porcine ear necrosis syndrome were observed in 80% of the weaned pigs at 45-50 days of age. Pathomorphological examinations were carried out on 10 pigs that had been found dead. The gross lesions ranged from mild, superficial dermatitis to severe, deep inflammation with exudation, ulceration and necrosis. Histopathological examination revealed erosive and ulcerative dermatitis of the pinna with neutrophilic and lymphocytic infiltration and bacterial colonies in the crusts. Staphylococcus aureus (MRSA strain), Staphylococcus hyicus and Streptococcus group C were cultivated from eight, S. hyicus from two ear tissue scraping samples. All 10 samples were positive for treponemes and phylogenetic analysis of two polymerase chain reaction products confirmed the relationship to Treponema (T.) medium/vincentii and Treponema pedis. Treponemes were also detected in seven oral swabs that were analysed to obtain evidence of the transmission of this bacterium by ear biting. The contribution of non-infectious factors to this misbehaviour could not be ruled out as the crude protein concentration of the feed was inappropriate and the climate of the pig house was suboptimal. The concentrations of selected mycotoxins in the feed were not elevated. However, the contribution of both infectious and non-infectious factors to the onset of disease was most probable.

Biochemical, carcass and meat quality alterations associated with different degree of lung lesions in slaughtered pigs.

This study examined the relationship between lung lesion severity and presence of antibodies of various respiratory pathogens, and the effects of lung lesion severity on growth performance, biochemical indicators, total aerobe counts, and carcass and meat quality indicators in total of 240 slaughter pigs originating from two farms with similar rearing conditions. Lung lesion severity was calculated based on the degree of pneumonia and pleurisy in slaughtered pigs. Two-step cluster analysis was used to place individual pigs to four clusters according to pneumonia and pleurisy scores: no lung lesions (cluster 1); mild lung lesions (cluster 2); moderate lung lesions (cluster 3); and severe lung lesions (cluster 4). ANOVA and post hoc pairwise comparisons using Tukey's test were performed to assess the differences between clusters in examined variables. Multivariate linear regression analysis was run to identify associations between lung lesions and examined variables. There was a strong evidence of association between the absence of lung lesions and increased albumin, sodium and chloride levels, daily weight gain, live weight, hot carcass weight, cold carcass weight, loin thickness and carcass lean content, and decreased haptoglobin, CK and LDH levels. Also, pigs without lung lesions produced the highest percentage of red, firm and nonexudative pork. Pigs having severe lung lesions had the highest percentage of simultaneously seropositive samples to SIV, PRRSV, PCV-2, PRCV, APP and M. hyopneumoniae. There was a strong evidence of association between the presence of severe lung lesions and decreased lactate, glucose, sodium, chloride and albumine levels, daily weight gain, live weight, hot carcass weight, cold carcass weight, loin thickness and carcass lean content, and increased CK, LDH and haptoglobin levels. There was a strong evidence of association between the presence of severe lung lesions in slaughered pigs and increased meat pH and sensory colour scores, and decreased drip, thawing and cooking losses and L* and b* values, which led to the highest occurrence of moderate DFD and DFD pork. There was a strong evidence of association between the presence of mild lung lesions in slaughtered pigs and decreased meat pH and sensory colour scores, and increased drip, thawing and cooking losses, L* and b* values, which led to the highest occurrence of moderate PSE and PSE pork. In conclusion, the presence of lung lesions, irrespective of severity, was significantly associated with alterations in the biochemical indicators, growth performance and carcass and meat quality in slaughtered pigs.

Morphological and immunophenotypic characteristics of the liver of swine naturally infected with hepatitis E virus.

Hepatitis E virus (HEV), the zoonotic agent of infectious hepatitis, is present in swine farms in different geographical areas. Little is known about the mechanism of liver damage and type of local immune response by HEV in swine. Therefore, the aim of this study was to determine the morphological and immunophenotypic characteristics of hepatic lesions caused by hepatitis E virus in naturally infected swine. In this study, liver samples of 12 slaughtered 10 weeks old pigs which were RT-PCR positive for HEV RNA in rectal swab samples have been used. Livers were macroscopically examined and samples were taken for histopathological, immunohistochemical (CD3, CD79α and TGF-ß1), semiquantitative, morphometric analysis, RT-nested-PCR, PCR and bacteriological analysis. Microscopically, mild and moderate multifocal lymphoplasmacytic hepatitis was observed. Apoptotic bodies were observed as areas of focal eosinophilic condensation in the cytoplasm of 33.33% liver samples, while in 16.67% liver samples portal fibrosis was detected. Immunohistochemically, portal and lobular lymphocytes in the mononuclear liver infiltrate were predominantly CD3+ T cells (234.80 ± 79.98). An intense TGF-ß1 positive reaction was observed within the mononuclear cell infiltrate as well as polymorphonuclear cells in liver samples with apoptosis of hepatocytes. In all 12 tested liver samples HEV RNA was detected by RT-nested-PCR. HEV is noncytopathic, and this finding provides further evidence for an immune mediated pathogenesis in hepatitis E virus infection in swine. Also, the role of CD3+ cells in hepatocyte damage is clearly demonstrated.

Molecular detection and characterization of Porcine Kobuvirus in domestic pigs and wild boars in Serbia.

Porcine Kobuvirus (PKV) infection is very common in pigs throughout the world. Since it has never been investigated in Serbia, to contribute to the knowledge of Porcine Kobuvirus, its role, and distribution, we tested 200 samples from domestic pigs and wild boars. From domestic pigs, 10 fecal, 22 spleen and 68 serum samples, and 100 spleen samples from wild boars were tested. The virus prevalence determined by real-time RT-PCR in domestic pigs was 22% and in wild boars 6%. The phylogenetic analysis of 3D region revealed that Serbian strains are closest related to the Hungarian strain from wild boar from 2011. This is the first report on PKV in Serbia in domestic pigs and wild boars, implying its wide circulation. Although the infection could not be directly related to any clinical manifestation, the frequency of virus found in feces suggests viral affinity to the gastrointestinal tract. However, due to the rather ubiquitous presence of PKV, the clinical and pathological assessment have to be considered when PKV infection is diagnosed.

Seroprevalence of hepatitis E in pigs and wild boars in the region of the city Belgrade.

INTRODUCTION: Hepatitis E is considered an emerging human viral disease with many evidences of zoonotic nature of disease, and swine are the main reservoir of HEV. The aim of this study was to determine HEV seroprevalence in commercial pig farms, backyard pigs, slaughtered pigs and wild boars in the region of the city Belgrade. METHODOLOGY: A total of 405 sera samples: 150 samples from 3 commercial pig farms, 70 samples from backyard pigs, 119 samples from slaughtered pigs and 66 samples from wild boars of the region of the city Belgrade, Serbia were analysed by commercial ELISA test. RESULTS: The overall HEV seroprevalence in 3 commercial pig farms was 55.33% (83/150). All tested farms (farm A, B and C) were positive on the presence of anti-HEV antibodies, respectively 58% (29/50), 54% (27/50) and 54% (27/50). From 70 tested backyard pigs, 75.71% (53/70) were tested seropositive. In total, 26 backyard pig holidngs were confirmed as positive to anti-HEV antibodies (81.25%). At slaughterhouse, 25% (8/32) weaned piglets and 20.69% (18/87) fattening pigs were tested positive on anti-HEV antibodies. Overall HEV seroprevalence in tested wild boar population was 52.25% (36/66). CONCLUSIONS: Detected very high seroprevalence of anti-HEV antibodies indicated an active circulation of HEV, being enzootic in the swine population, and wild boars, as well, in the region of the city Belgrade.