Virulence genes and plasmid profiles in Rhodococcus equi isolates from domestic pigs and wild boars (Sus scrofa) in Brazil

The virulence genes and plasmid profiles of 23 Rhodococcus equi isolates from 258 lymph nodes from domestic pigs (129 nodes with lesions and 129 without lesions) and 120 lymph nodes from slaughtered wild boars (60 nodes with lesions and 60 without) were characterized. R. equi was obtained from 19 lymph nodes of domestic pigs, 17 with, and two without lesions, and from four lymph nodes with lesions, from wild boars. The 23 isolates were tested for the presence of vapA and vapB genes, responsible for the 15–17 and 20 kDa virulence-associated proteins, respectively, by PCR in order to characterize as virulent (VapA), intermediately virulent (VapB) and avirulent. Plasmid DNAs were isolated and analyzed by digestion with restriction endonucleases to estimate size and compare their polymorphisms. Of the 19 domestic pigs strains, seven (36.8%) were avirulent and 12 (63.2%) were intermediately virulent, with the intermediately virulent isolates being plasmid types 8 (8 isolates), 10 (2 isolates), 1 (1 isolate) and 29 (1 isolate). The plasmid type of four strains isolated from wild boars was also intermediately virulent type 8. None of the domestic pigs and wild boar isolates showed the vapA gene. These findings demonstrate a high occurrence of plasmid type 8 in isolates from pigs and wild boars, and the similarity of plasmid types in the domestic pigs, wild boars and human isolates in Brazil.     

Trichinella spiralis in wild boars (Sus scrofa)

During the period 1.7. 1972--31.6. 1977 muscle samples from 137 wild boars were examined for Trichinella spiralis. Larvae of T. spiralis were demonstrated in 4 animals. The major part (83) of the wild boars examined, including the 4 positive ones, originated from one particular game park. The rate of infection with T. spiralis in the game park concerned was 4.8%. Calculated on the basis of the total of animals examined, the rate of infection was 2.9%.     

Virulence-associated protein characterisation of Rhodococcus equi isolated from bovine lymph nodes

Rhodococcus equi has a low pathogenicity in cattle, but it occasionally causes lymph node granulomas, which are detected at abattoir post mortem inspection, and must be distinguished from tuberculous granulomas. Lymph node lesions were detected in 6719 cattle, from a total of 3,263,622 cattle examined post mortem in abattoirs, in the Republic of Ireland, during 1997 and 1998. Histological examination was performed on all lesions, principally for the purpose of identifying animals with tuberculosis. A total of 1122 of the lesions were cultured on blood agar and on Stonebrinks and Lowenstein-Jensen medium containing pyruvate, because the histological findings were difficult to interpret or were suggestive of R. equi infection. R. equi was isolated from 264 lesions. Almost all of the R. equi granulomas were confined to a single lymph node, and were present predominantly in the retropharyngeal, bronchial and mediastinal lymph nodes. R. equi granulomas were present in a significantly higher proportion of the lesions detected in steers and heifers compared to cows. The prevalence in the total population of 3.3 million cattle examined post mortem was 0.008%. The 15-17kDa antigens, associated with virulence in this organism, and the 20kDa antigen, associated with intermediate virulence, were not detected in isolates from 146 cattle, analysed by immunoblot assays. A PCR assay to detect the plasmid gene encoding the 15-17kDa antigens was also negative for isolates from these 146 animals. Plasmids were not detected in 30 isolates which were examined.     

Typing of Rhodococcus equi isolated from submaxillary lymph nodes of pigs in Japan

Isolation of Rhodococcus equi from the submaxillary lymph nodes of pigs, with or without caseous lymphadenitis, and typing of the isolates by two serological methods were carried out. The rate of isolation of the organisms from the lymph nodes of pigs was 5 times higher in the lymph nodes with caseous lymphadenitis than in those without the lesion. Of 219 isolates, 146 (66.7%) were typable by the method of Prescott, while all the 219 isolates (100%) were typable by the method of Nakazawa et al. The most frequently isolated were serotype 2 of Prescott (identical to serogroup 16 of Nakazawa et al.), and serogroup 3 of Nakazawa et al., which did not correspond with any serotypes of Prescott. Serotypes/serogroups of R. equi from pigs were thus first clarified in Japan.     

Isolation and characterisation of Mycobacterium avium and Rhodococcus equi from granulomatous lesions of swine lymph nodes in Slovenia

Granulomatous lesions in bovine and especially swine lymph nodes are still frequently observed during routine veterinary meat inspections even though Mycobacterium bovis infections are no longer detected in domestic animals in Slovenia. Different lymph nodes of pigs (n = 260) were investigated using classical bacteriological and molecular methods. Mycobacterium avium alone was isolated in 47.3% of pigs and in mixed infection with Rhodococcus equi in 3.9% of pigs. R. equi alone was isolated in 27.3% and in mixed infection with mycobacteria other than M. avium in 1.5% of pigs. A total of 133 M. avium isolates were typed using the IS1245, IS901 and FR300 PCR. Almost two thirds (60.9%) of isolates belonged to M. avium hominissuis (IS901-, IS1245+ genotype), 33.8% of isolates belonged to M. avium avium (IS901+, IS1245+ genotype) and 5.3% of isolates remained non-typed. Fifty out of 85 R. equi isolates were tested for the virulence-associated antigens (VapA and VapB). Nearly two thirds (60.0%) were positive for VapB while all the other isolates were VapA- and VapB-negative.     

Salmonella serotypes in wild boars (Sus scrofa) hunted in northern Italy

Background

Salmonella species (spp.) are zoonotic enteric bacteria able to infect humans, livestock and wildlife.However, little is known about the prevalence and the presence of the different serovars in wildlife. Considering the wide distribution of wild boars and the feeding behaviour (omnivorous scavengers), wild boars may be a good indicator for environmental presence of Salmonella spp. The aims of this study were to determine the presence of Salmonella spp. in hunted wild boars and to determine the serotype the isolated strains.

Findings

Over three hunting seasons, the intestinal contents of 1,313 boars hunted in northern Italy were sampled and cultured. Salmonella spp. were isolated from 326 boars (24.82%). Thirty different serovars belonging to three different S. enterica spp. were found. Twenty-one serovars of S. enterica subsp. Enterica were found including the human pathogens S. Typhimurium and S. Enteritidis. In addition, nine serovars belonging to S.enterica subsp. diarizonae and S. enterica subsp. houtenae were detected.

Conclusions

Considering the widespread occurrence of wild boars in Europe, the epidemiological role of this species in relation to salmonellosis might be relevant and should be further investigated. Wild boars may act as healthy carriers of a wide range of Salmonella serotypes.     

Phenotypic and genotypic characterization of antimicrobial resistance in faecal enterococci from wild boars (Sus scrofa)

The objective was to study the prevalence of antimicrobial resistance and the mechanisms implicated in faecal enterococci of wild boars in Portugal. One hundred and thirty-four enterococci (67 E. faecium, 54 E. hirae, 2 E. faecalis, 2 E. durans and 9 Enterococcus spp.) were recovered from 67 wild boars (two isolates/sample), and were further analysed. High percentages of resistance were detected for erythromycin, tetracycline, and ciprofloxacin (48.5%, 44.8%, and 17.9%, respectively), and lower values were observed for high-level-kanamycin, -streptomycin, chloramphenicol, and ampicillin resistance (9%, 6.7%, 4.5%, and 3.7%, respectively). No isolates showed vancomycin or high-level-gentamicin resistance. The erm(B), tet(M), aph(3')-IIIa, and ant(6)-I genes were demonstrated in all erythromycin-, tetracycline-, kanamycin-, and streptomycin-resistant isolates, respectively. Specific genes of Tn916/Tn1545 and Tn5397 transposons were detected in 78% and 47% of our tet(M)-positive enterococci, respectively. The tet(S) and tet(K) genes were detected in one isolate of E. faecium and E. hirae, respectively. Three E. faecium isolates showed quinupristin-dalfopristin resistance and the vat(E) gene was found in all of them showing the erm(B)-vat(E) linkage. Four E. faecium isolates showed ampicillin-resistance and all of them presented seven amino acid substitutions in PBP5 protein (461Q-->K, 470H-->Q, 485M-->A, 496N-->K, 499A-->T, 525E-->D, and 629E-->V), in relation with the reference one; a serine insertion at 466' position was found in three of the isolates. Faecal enterococci from wild boars harbour a variety of antimicrobial resistance mechanisms and could be a reservoir of antimicrobial resistance genes and resistant bacteria that could eventually be transmitted to other animals or even to humans.     

First reports of Trichinella pseudospiralis in wild boars (Sus scrofa) of Italy

Trichinella pseudospiralis is a non-encapsulated species infecting both mammals and birds. In Italy, this parasite was reported only in two night-birds of prey of Central Italy. In January 2010, Trichinella larvae were detected in three wild boars (Sus scrofa) of two regions of Northern Italy by enzymatic digestion. The parasites were identified as T. pseudospiralis by multiplex-PCR. The first infected wild boar was hunted in the Emilia Romagna region and the other two infected wild boars were bred outdoors in a small family farm of the Friuli Venezia Giulia region. These new epidemiological data reinforce the role of the wild boar as the main reservoir of T. pseudospiralis in Europe.     

Seroprevalence of brucellosis, tularemia, and yersiniosis in wild boars (Sus scrofa) from north-eastern Germany

Brucellosis and tularemia are classical zoonotic diseases transmitted from an animal reservoir to humans. Both, wildlife and domestic animals, contribute to the spreading of these zoonoses. The surveillance of the animal health status is strictly regulated for domestic animals, whereas systematic disease monitoring in wildlife does not exist. The aim of the present study was to provide data on the prevalence of anti-Brucella, anti-Francisella and anti-Yersinia antibodies in wild boars from North-Eastern Germany to assess public health risks. A total of 763 sera of wild boars from Mecklenburg-Western Pomerania hunted in 1995/1996 were tested using a commercially available Brucella suis ELISA, an in-house lipopolysaccharide (LPS)-based Francisella ELISA, and commercially available Western blot kits for the detection of anti-Francisella and anti-Yersinia antibodies. The Yersinia enterocolitica O:9 LPS is able to induce serological cross-reactions indistinguishable from brucellosis due to a similar immunodominant epitope in the Brucella O-polysaccharide. The Yersinia Western blot assay was, therefore, based on five recombinant Yersinia outer proteins which have been proved to be specific for the serodiagnosis of yersiniosis. Anti-Brucella, anti-Francisella and anti-Yersinia antibodies were detected in 22.0%, 3.1%, and 62.6% of the wild boars, respectively. The high seroprevalence of tularemia and brucellosis in wild boars indicates that natural foci of these zoonoses are present in wildlife in Germany. However, the impact of transmission of zoonotic pathogens from wildlife to livestock is unknown. Only careful and systematic monitoring will help to prevent the (re)emergence of these zoonotic diseases in domestic animals and consequently human infection.     

Effect of area decrease in a food competition situation in captive wild boars (Sus scrofa)

The aim of the present study was to examine the effect of area reduction on the hierarchy-dependent behaviors of wild boars and crossbred sows (wild boar × Vietnamese pot-bellied pig) living in captivity, with regard to a food competition situation. We first defined the hierarchy system among 7 individuals, living together for more than a year, with a mathematical model based on wins and defeats. We then tested the possibility of a correspondence between the rank position and the age and/or weight. In a first experiment, we defined the frequency of dominant and submissive behavioral elements depending on the rank and on the group level in a food competition situation. We analyzed individually the time spent feeding. In a second experiment, we reduced the size of their living area and observed the potential modifications of the dominant and submissive elements’ frequency as well as the time spent feeding.We found a linear hierarchy among the sows. We did not find any relationship between the rank and the age or the rank and the weight of the animals. However, after excluding the youngest and the lightest leader from the analysis, significant correspondence was found among the aforementioned variables. In such cases, the older and heavier sows occupied the higher ranks in the hierarchy. We also observed that the sow with the higher rank position spent more time feeding and presenting aggressive behaviors compared with the other individuals, whereas the sow with the lowest rank position spent the most time displaying submissive behavior. Moreover, the frequency of dominant and submissive behavioral elements increased when reducing the size of the living area.Based on our results, we found that the area reduction and, therefore, the higher density increased the frequency of aggressive and submissive behavioral elements of the sows.     

Fasciola hepatica in wild boar (Sus scrofa) from Italy

Fasciola hepatica is a trematode infecting ruminants worldwide, occasionally reported in a wide range of animal species, including humans. According to the WHO, fasciolosis is recognized as a re-emerging neglected tropical disease, responsible for endemic and epidemic outbreaks in humans. Although the main hosts of the parasite are represented by cattle, sheep and goats, wildlife may be involved in its circulation. Here we firstly report F. hepatica in a wild boar from Italy (southern area) and characterize it both morphologically and molecularly. The nad1 gene analysis of specimens analyzed, revealed a high genetic similarity with those of humans from Iran and Peru, as well as a close phylogenetic relationship to those in ruminants from Brazil, Ecuador and Egypt. Considering the increase in the wild boar populations in urban and peri-urban areas, a potential role of this ungulate in the circulation of this zoonotic trematode is suggested.     

Porcine lymphotropic herpesvirus (Gammaherpesvirinae) DNA in free-living wild boars (Sus scrofa Linnaeus, 1758) in Brazil

BackgroundSuid gammaherpesvirus 3, 4, and 5 (porcine lymphotropic herpesvirus – PLHV-1, -2, and -3) are viruses that infect domestic and feral pigs.ObjectivesThis study examined the presence of PLHV DNA in biological samples from free-living wild boars circulating in a Brazilian geographical region with a high density of commercial domestic pigs.MethodsLung samples of 50 free-living wild boars were collected by exotic wildlife controller agents between 2017 and 2019 in the state of Paraná, southern Brazil. Lung and spleen fragments were obtained from six fetuses collected by hysterectomy post mortem from a pregnant sow. A polymerase chain reaction (PCR) assay using consensus primers (pan-herpesviruses) was performed to detect PLHV DNA. The samples showing positive results for PLHV DNA were submitted to single-round PCR assays with the specific primers for identifying PLHV-1 (213-S/215-As), PLHV-2 (208-S/212-As), and PLHV-3 (886s/886As). The specificity of the species-specific PCR products was assessed by nucleotide sequencing of the amplicons.ResultsForty-eight (96%) of the 50 lung samples analyzed were positive for PLHV by PCR using pan-herpesvirus primers. In 33 (68.75%) of the positive samples, at least two PLHV species were identified simultaneously. The DNA of PLHV-1, -2, and -3 was found in free-living wild boars of all ages, but not in the fetuses, even though they were from a sow that tested positive for all three viruses.ConclusionThese viruses are endemic to the population of feral pigs in the Brazilian region evaluated, as well as in domesticated pigs.     

Molecular detection of Mycoplasma suis in captive white-lipped peccaries (Tayassu pecari) and wild boars (Sus scrofa) in Brazil

Mycoplasma suis, the etiological agent of swine hemoplasmosis, is an epicellular bacterium that adheres to the surface of pig erythrocytes leading to deformations of the target cells. Little is known about the occurrence of M. suis in wild swine populations around the world, its economic impact on swine herds, and the risk of human infection. The aim of this study was to investigate, by quantitative real-time PCR (qPCR) based on the 16S rRNA gene, the occurrence of M. suis in a captive population of white-lipped peccaries (100 Tayassu pecari) and in free-living wild boars (14 Sus scrofa) in Brazil. None of the white-lipped peccaries were positive for M. suis, whereas seven (50%) wild boars were positive in qPCR assays. The quantification of M. suis-16S rRNA copies/μL ranged from 1.42 × 10° to 3.906 × 10¹ in positive animals, indicating a low bacteremia and a chronic carrier status in free-living wild boars. In conclusion, M. suis might be a non-frequent pathogen in wild suids maintained in captivity. Despite the low bacteremia, the prevalence of M. suis in wild boar population in Brazil seems to be high.     

Post‐mortem examination of the reproductive organs of female wild boars (Sus scrofa) in Sweden

In recent decades, wild boars (Sus scrofa) have increased in numbers and distribution in Europe. Compared to other wild ungulates of similar body size, wild boars have a high reproductive capacity. To increase the knowledge of wild boar reproduction, the objective of this study was to investigate characteristics of reproductive organs, and to provide information on the occurrence of abnormalities in reproductive organs from free‐ranging female wild boars. Between December 2011 and December 2015, reproductive organs from female wild boars (>30 kg body weight), were collected during hunting in four Swedish counties at estates where supplementary feeding was applied. The organs were macroscopically examined and measured. The stage of the reproductive cycle was defined according to the ovarian structures and in relation to uterus characteristics. Observed abnormalities were noted. The results from 569 animals that met the requirements to be included in this study showed significant differences in weight and length of the uterus between the various reproductive stages. Sampling region had significant effect on these differences. Abnormalities in the reproductive organs were present in approximately 10% of the examined animals. The prevalence of abnormalities increased significantly with age and was significantly affected by sampling region.     

PCV2-DNA in formalin-fixed and paraffin embedded lymph nodes of wild boar (Sus scrofa ssp. scrofa): one sampling approach for two laboratory techniques

Superficial inguinal lymph nodes from 72 wild boars examined in a previous immunohistochemical (IHC) study on porcine circovirus type 2 (PCV2) were selected for a PCV2 polymerase chain reaction (PCR) analysis. Four of these lymph nodes were PCV2-IHC strongly positive with PMWS histological lesions (outcome 1), 6 weak to mild PCV2-IHC positive without PMWS histological lesions (outcome 2) and 62 PCV2-IHC negative. Considering IHC the gold standard for diagnosis, the aims of the study were to evaluate the suitability of the PCV2-DNA extraction from formalin-fixed and paraffin-embedded (FFPE) tissue and the sensitivity and specificity of PCR under two IHC interpretations criteria: (A) the sample was considered positive if the result was outcome 1; (B) the sample was considered positive if the result was outcome 1 or 2. Under (A) criteria, sensitivity and specificity of PCR were 100% and 89.7%, respectively; the Cohen''s Kappa coefficient was 0.49. Under (B) criteria, sensitivity and specificity of PCR were 80.0% and 95.2%, respectively; the Cohen''s Kappa coefficient was 0.72. The high Cohen''s Kappa coefficient under the (B) interpretative criteria indicates good agreement between the two methods. In conclusion, 1) DNA extracted from FFPE specimens of wild boar is suitable for PCR and further represents a screening test for PCV2/PCVD (PCV2 Diseases) investigations in wild boar as well; 2) routine histological sampling can also be useful for PCV2 virological studies in wild boar.