Prevalence of Leptospira and Brucella antibodies in wild boars (Sus scrofa) in Tuscany, Italy

Five hundred sixty-two blood samples were collected from wild boars (Sus scrofa) shot in six districts of Tuscany, central Italy, between 1997 and 2000. Sera were examined for antibodies specific for Leptospira interrogans by microagglutination test and Brucella spp. by the Rose Bengal test and indirect enzyme-linked immunosorbent assay. Thirty-four (6.0%) samples tested positive for anti-Leptospira antibodies, 29 (5.1%) sera were positive for anti-L. interrogans serovar bratislava antibodies (titres ranging from 1:100-1:400), and 5 (0.9%) sera were positive for anti-L. interrogans serovar icterohaemorrhagiae antibodies (titres 1:100). All the examined sera were negative for anti-Brucella antibodies.     

Prevalence of Streptococcus suis genotypes in wild boars of Northwestern Germany

Invasive serotype 2 (cps2+) strains of Streptococcus suis cause meningitis in pigs and humans. Four case reports of S. suis meningitis in hunters suggest transmission of S. suis through the butchering of wild boars. Therefore, the objective of this study was to investigate the prevalence of potentially human-pathogenic S. suis strains in wild boars. S. suis was isolated from 92% of all tested tonsils (n=200) from wild boars. A total of 244 S. suis isolates were genotyped using PCR assays for the detection of serotype-specific genes, the hemolysin gene sly, and the virulence-associated genes mrp and epf. The prevalence of the cps2+ genotype among strains from wild boars was comparable to that of control strains from domestic pig carriers. Ninety-five percent of the cps2+ wild boar strains were positive for mrp, sly, and epf*, the large variant of epf. Interestingly, epf* was significantly more frequently detected in cps2+ strains from wild boars than in those from domestic pigs; epf* is also typically found in European S. suis isolates from humans, including a meningitis isolate from a German hunter. These results suggest that at least 10% of wild boars in Northwestern Germany carry S. suis strains that are potentially virulent in humans. Additional amplified fragment length polymorphism analysis supported this hypothesis, since homogeneous clustering of the epf* mrp+ sly+ cps2+ strains from wild boars with invasive human and porcine strains was observed.     

Prevalence of antibodies to porcine parvovirus in wild boars (Sus scrofa) in Croatia

Serologic evidence of exposure to porcine parvovirus (PPV) in the wild boar (Sus scrofa) in Croatia was investigated. Serum samples from 219 wild boars captured during 2003 from 12 different locations in the Republic of Croatia were tested by using a commercial enzyme-linked immunoassay (ELISA) and a hemagglutination inhibition (HI) test. Antibodies to PPV were detected in 91 (41.6%) of tested samples and positive results were detected in wild boar from all sample locations. Adults had a significantly higher prevalence (70%) than juveniles (31%; P < 0.01). Our results indicate that wild boar populations throughout the Republic of Croatia are exposed to PPV.     

Prevalence of antibody titers to Leptospira spp. in Minnesota white-tailed deer.

Serum samples (n = 204) from 124 white-tailed deer (Odocoileus virginianus) in northeastern Minnesota (USA) were collected from 1984 through 1989 and tested for antibodies to six serovars of Leptospira interrogans (bratislava, canicola, grippotyphosa, hardjo, icterohemorrhagiae, and pomona) using a microtiter agglutination test. Eighty-eight (43%) sera were positive at greater than or equal to 1:100 for antibodies against serovars pomona and/or bratislava; none was positive for any of the other four serovars. None of the 31 sera collected in 1984-85 was positive, whereas all 54 sera collected from 1986 through 1988 had titers of greater than or equal to 1:100. During 1989, only 34 (29%) of 119 sera had titers of greater than or equal to 1:100. Based on these results, we believe there to be wide variability in exposure of Minnesota deer to Leptospira interrogans.     

Color discrimination in wild boars

Two experiments were carried out in order to clarify the color perception of Japanese wild boarsSus scrofa leucomystax. Two females were trained using an operant conditioning technique to press a switch under a positive stimulus color card in order to receive food as a reward. In Exp. 1, they were tested for discrimination between 3 colors (red, green and blue) and gray. The luminosity of all colors was the same. The wild boars succeeded in discrimination tests between blue and gray, but failed to discriminate red from gray. They also did not discriminate green from gray so clearly as blue from gray. In Exp. 2, the same wild boars were tested to discriminate between 8 kinds of color, which were created by gradating green yellow into red purple except for the 3 colors used in Exp. 1, and gray. They could clearly discriminate blue, purple blue and a part of purple from gray. In these experiments, wild boars were capable of recognizing bluish colors. However, for colors approaching green or yellow, they failed the test by degrees.     

Presence of pathogenic Leptospira spp. in the reproductive system and fetuses of wild boars (Sus scrofa) in Italy

Leptospirosis is a re-emerging and globally spread zoonosis caused by pathogenic genomospecies of Leptospira. Wild boar (Sus scrofa) are an important Leptospira host and are increasing in population all over Europe. The aim of this investigation was to evaluate Leptospira spp. infection in the reproductive systems of wild boar hunted in two Italian regions: Tuscany and Sardinia. From 231 animals, reproductive system tissue samples (testicles, epididymides, uteri) as well as placentas and fetuses were collected. Bacteriological examination and Real-Time PCR were performed to detect pathogenic Leptospira (lipL32 gene). Leptospires were isolated from the testicles and epididymides of one adult and two subadult wild boar. Four isolates from the two subadult males were identified as Leptospira interrogans serogroup Australis by MLST, whereas Leptospira kirschneri serogroup Grippotyphosa was identified from the adult testicles and epididymis. Using Real-Time PCR, 70 samples were positive: 22 testicles (23.16%) and 22 epididymides (23.16%), 10 uteri (7.35%), 3 placentas (6.66%), and 13 fetuses (28.88%). Amplification of the rrs2 gene identified L. interrogans and L. kirschneri species. The results from this investigation confirmed that wild boar represent a potential source of pathogenic Leptospira spp. Isolation of Leptospira serogroups Australis and Grippotyphosa from the male reproductive system and the positive Real-Time PCR results from both male and female samples could suggest venereal transmission, as already demonstrated in pigs. Furthermore, placentas and fetuses were positive for the lipL32 target, and this finding may be related to a possible vertical transmission of pathogenic Leptospira.     

Fiber types and metabolic characteristics in muscles of wild boars, normal and halothane sensitive Swedish landrace pigs

Muscle fiber characteristics, glycogen content and enzyme activities were studied in muscles of six Swedish landrace pigs, six wild boars and in three halothane sensitive landrace pigs. The wild boars have a higher proportion of type I and IIA fibers compared with Swedish landrace pigs. Fiber composition is similar in landrace pigs and halothane sensitive landrace pigs. The wild boars revealed the highest citrate synthase (CS) and 3-OH-acyl-CoA dehydrogenase (HAD) activities and the lowest glycogen content compared with the other two groups. Lower CS and HAD activities were observed in the halothane sensitive pigs compared with the other pigs. The data show that wild boars have a higher and halothane sensitive landrace pigs a lower aerobic capacity in skeletal muscles compared with Swedish landrace pigs.     

Trichinella nativa in sylvatic wild boars.

Of 17 Trichinella isolates from domestic pigs and wild boars (Sus scrofa) in regions where Trichinella nativa is widespread among sylvatic animals, two wild boars from Estonia were found to be naturally infected with this Trichinella species. The other 15 animals were infected with Trichinella spiralis. Trichinella nativa is tolerant to freezing when in the muscles of carnivores. The biological characteristics and temperature tolerance of this species in swine need to be further investigated if pork is certified for consumption following freezing.     

Leptospira antibodies in wild boars (<Emphasis Type="Italic">Sus scrofa</Emphasis>) in Slovenia

Serum samples collected from 437 shot wild boars (Sus scrofa) were tested for the presence of antibodies against Leptospira interrogans sensu lato in wild boar in Slovenia. Assessment of leptospira-specific antibodies was performed by microscopic agglutination test. Antibodies against at least one of the pathogenic serovars were detected in 200 (45.8%) sera. From 200 positive samples, 100 samples (50%) had positive titre against a single serovar, while 100 (50%) samples had positive titres against two or more serovars. The most frequently detected antibodies were those against serovar Tarassovi. This investigation confirmed the presence of different pathogenic serovars in wild boar across Slovenia. It can be concluded that wild boars are natural reservoirs of at least some of the leptospiral serovars that represent a potential source of leptospirosis for other wild and domestic animals, as well as for humans.     

Prevalence of antibodies to selected viral pathogens in wild boars (Sus scrofa) in Croatia in 2005-06 and 2009-10

We determined prevalence of antibody to selected viral pathogens important for domestic pigs and livestock in 556 wild boar (Sus scrofa) sera collected during 2005-06 and 2009-10 in four counties in Croatia. These counties account for an important part of the Croatian commercial pig production and have a high density of wild boars. Samples were tested for antibodies to porcine parvovirus (PPV), Aujeszky's disease virus (ADV), porcine circovirus type 2 (PCV2), swine influenza virus, porcine respiratory and reproductive syndrome virus (PRRSV), porcine respiratory coronavirus (PRCV), transmissible gastroenteritis virus, and swine vesicular disease virus (SVDV). Antibodies to all of the infectious pathogens except SVDV were detected. There was a statistically significant difference in prevalence between the two periods for PPV, ADV, PCV2, PRRSV, and PRCV, with a higher prevalence of PPV and ADV in the 2009-10 period (P<0.05). During the same period, the prevalence of PCV2, PRRSV, and PRCV was lower (P<0.05). Our results provide information on the current disease exposure and health status of wild boars in Croatia and suggest that wild boars may act as a reservoir for several pathogens and a source of infection for domestic pigs and other livestock as well as humans, especially for ADV.     

A genetic method to distinguish crossbred Inobuta from Japanese wild boars

To distinguish pig-wild boar crossbred Inobuta from Japanese wild boar populations, a genetic method by using mitochondrial DNA (mtDNA) haplotypes and the nuclear glucosephosphate isomerase-processed pseudogene (GPIP) was developed. Sixteen mtDNA haplotypes from 152 wild boars from Kyushu, Shikoku and Honshu islands of Japan were distinct from those from Asian and European domestic pigs. Five alleles of GPIP were classified into two groups: 1). alleles GPIP*1, GPIP*3 and GPIP*3a from Japanese wild boars, Asian wild boars and domestic pigs; 2). alleles GPIP*4 and GPIP*4a from European wild boars and domestic pigs. An extensive genetic survey was done to distinguish the crossbred Inobuta from 60 wild boars hunted on Tsushima Island, Goto Islands, and Nagasaki and Ooita Prefectures. The mtDNA haplotypes from the 60 samples showed Japanese wild boars, but four wild boar samples from Nagasaki Prefecture had the European GPIP allele, GPIP*4. These results showed that nuclear DNA polymorphism analysis is useful, in addition to mtDNA haplotype assay, to detect "Inobuta" having the European genotype from Japanese wild boar populations.     

Occurrence of yersiniosis and listeriosis in wild boars in Japan

From December 1994 to February 1995, 131 wild boars (Sus scrofa leucomysta) living in a mountainous area in Japan were examined for yersiniosis and listeriosis. Of 131 wild boars, 76 (58%) were males and 55 (42%) were females. Four Yersinia spp. including Y. pseudotuberculosis, Y. enterocolitica, Y. frederiksenii, and Y. aldovei, were isolated from 49 (37%) of 131 wild boars. Yersinia pseudotuberculosis was isolated from five (4%) of 131 wild boars. All Y. pseudotuberculosis isolates were serotype 4b and harbored virulence plasmids. Yersinia pseudotuberculosis was isolated only from boars under 2-yr-old. No human pathogenic Y. enterocolitica was isolated. Listeria monocytogenes was isolated from two (1%) of the wild boars and both isolates were serotype 4b. These findings indicated that wild boar could be a reservoir of Y. pseudotuberculosis and L. monocytogenes in Japan.     

Antibodies to selected viral disease agents in wild boars from the Czech Republic

Blood samples were collected from wild boar (Sus scrofa) shot during the hunting season from 1999 to 2005 in the Czech Republic. Sera were tested by enzyme-linked immunosorbent assay for the presence of antibodies against classical swine fever virus (CSFV), swine vesicular disease virus (SVDV), Aujeszky's disease virus (ADV), and bovine viral diarrhea virus (BVDV). Indirect fluorescence antibody test was used for detection of antibodies against porcine circovirus type 2 (PCV-2) and transmissible gastroenteritis virus (TGEV). Antibodies against ADV, BVDV, PCV-2, and TGEV were detected in 30% (101 of 338), 1% (2 of 352), 43% (57 of 134), and 1% (1 of 134) of wild boars, respectively. Sera of 6,471 and 362 tested wild boars were negative for the presence of antibodies against CSFV and SVDV, respectively. This is the first survey of TGEV antibodies in wild boars and the first serologic survey of viral diseases in wild boars in the Czech Republic. Wild boars in the Czech Republic may act as a potential reservoir of ADV and thus have a role in the epidemiology of this disease.     

Carriage of antibiotic-resistant bacteria in urban versus rural wild boars

The Western European population of wild boar (Sus scrofa) has increased its distribution over the past several decades, and some populations have colonized areas strongly influenced by human activity. Wild boars are known carriers of antibiotic-resistant bacteria acquired from the environment, and urban populations of wild boars may be more exposed than their rural counterparts. In this work, we compared the frequency of antibiotic resistance in indicator bacteria (Escherichia coli, Enterococcus faecalis, Enterococcus faecium) isolated from urban wild boars with that from rural wild boars in NE Spain. We further assessed whether bacterial isolates from the urban wild boars had a higher probability of showing antibiotic resistance when their host was highly associated to urban features. Seventy-two and 100 bacterial isolates from urban and rural habitat, respectively, were screened for antibiotic resistance against a set of antibiotics (13 per bacterial species). We found a significantly higher frequency of E. faecium showing resistance to tetracycline (70.0% vs 36.4%) and high-level resistance to streptomycin (30.0% vs 4.5%) in urban wild boars compared to rural wild boars (p?<?0.05). E. faecalis was more frequently resistant to trimethoprim in urban than rural wild boars (33.3% vs 0.0%, p?<?0.05). In isolates from urban origin, 55.6% of the likelihood of detecting antibiotic resistance depended only on the bacterial species, being more likely in the enterococci than in E. coli. These results suggest that urban wild boars may be more exposed to certain antibiotic-resistant bacteria or antibiotic resistance genes that they may acquire from the urban environment, although implications are uncertain.     

Sylvatic and domestic Trichinella spp. in wild boars; infectivity, muscle larvae distribution, and antibody response

Thirty-six wild boars were inoculated with Trichinella spiralis, Trichinella nativa, Trichinella britovi, Trichinella pseudospiralis (USSR), T. pseudospiralis (USA), T. pseudospiralis (AUST), Trichinella murrelli, Trichinella T6, and Trichinella nelsoni. The wild boars were killed at 5 and 10 wk postinoculation (PI), and the number of muscle larvae per g (lpg) of tissue was determined for 18 muscles or muscle groups. Five weeks PI, all Trichinella genotypes had established as muscle larvae, but their infectivity varied widely: T. spiralis established in high numbers (mean = 296 lpg), T. britovi, T. nelsoni, and 1 of the T. pseudospiralis genotypes (AUST) in moderate numbers (mean = 53-74 lpg), whereas the remaining genotypes were poorly infective (mean 2-16 lpg). Because of considerable weight gain of the wild boars, an estimated total larval burden (live weight x lpg) was calculated for each animal. The total larval burden did not change significantly over time for T. spiralis, T. murrelli, T. britovi, T. nelsoni, and T. pseudospiralis (USA and USSR), whereas a significant reduction could be demonstrated for T. nativa, Trichinella T6, and T. pseudospiralis (AUST). Diaphragm and tongue were predilection sites in wild boars, independent of Trichinella genotype and infection level. At low infection levels, a greater percentage of larvae were found in diaphragm and tongue at 10 wk than 5 wk PI. Antibody responses increased rapidly between weeks 3 and 5 PI. For T. spiralis and T. nelsoni, the high antibody level persisted throughout the experimental period, but for T. nativa, T. britovi, T. murrelli, or Trichinella T6, the levels declined. For T. pseudospiralis, the antibody response increased more gradually between weeks 3 to 10 PI. Infection with all genotypes of Trichinella were detected using any of 7 excretory-secretory antigens, which points to the potential use of 1 common antigen for epidemiological studies on Trichinella in wild boars. In conclusion, T. spiralis is highly infective to wild boars, T. britovi, T. nelsoni, T. pseudospiralis (USA), and T. pseudospiralis (USSR) are moderately infective, and T. nativa, T. murrelli, T. pseudospiralis (AUST), and Trichinella T6 are poorly adapted to this host species.     

A serological study on brucellosis in wild boars in Germany

A recent outbreak of brucellosis in an outdoor pig herd, where wild boars were identified as the most probable source of infection, prompted us to conduct a serological study on wild boars from five federal states of Germany. A total of 885 sera were examined using a combination of screening and confirmatory testing, i.e. indirect enzyme-linked immunosorbent assay (ELISA) followed by complement fixation and slow agglutination tests. Seroprevalences of Brucella suis antibodies in the various regions were between 0 and 28.5% in the ELISA. After confirmatory testing, the amount of positive sera was lower and reached only up to 12.1%, dependent on the method. Although wild boars usually harbour B. suis biovar 2, which is less virulent for humans, a zoonotic risk for persons dealing with these animals and their carcasses cannot be ruled out.     

Assessment of microbial carcass contamination of hunted wild boars

To investigate the microbiological conditions of hunted wild boar carcasses and factors that contribute to the microbial carcass contamination, skin and carcass meat swab samples from 210 hunted wild boars were collected from freshly shot animals. The mean aerobic colony counts (ACCs) and Enterobacteriaceae counts on the skin were 5.2 and 3.6 log₁₀ CFU/cm², with 1.4% of animals’ skin tested positive for Salmonella spp. Slightly higher mean ACC and Enterobacteriaceae counts of 5.4 and 3.8 log₁₀ CFU/cm² were obtained from carcass meat with Salmonella spp. prevalence of 1.9%. Inadequate hygiene practices in handling and dressing wild boar carcasses, such as evisceration in the laying position on the ground and practice of skin and interior carcass surface washing after evisceration, were found to have the most significant influence on the microbiological conditions of final carcasses. Therefore, these findings indicate the need for the implementation and strict adherence to good hygiene practice in hunting estates and game handling establishments.     

Antibodies to selected viral and bacterial pathogens in European wild boars from southcentral Spain

Serum samples from 78 European wild boars (Sus scrofa) harvested during the 1999-2000 hunting season were tested for antibodies to Brucella spp., classical swine fever virus, Erysipelothrix rhusiopathiae, Haemophilus parasuis, Leptospira interrogans serovar pomona, Mycoplasma hyopneumoniae, pseudorabies virus (PRV), porcine parvovirus (PPV), porcine reproductive and respiratory syndrome virus, Salmonella serogroups B, C, and D, Streptococcus suis, and swine influenza virus (SIV) serotypes H1N1 and H3N2. Samples were collected from Sierra Morena and Montes de Toledo in southcentral Spain. Antibodies were detected to PRV (36%), L. interrogans serovar pomona (12%), PPV (10%), E. rhusiopathiae (5%), SIV serotype H1N1 (4%), Salmonella serogroup B (4%), and Salmonella serogroup C (3%). Our results suggest that more research is needed to describe the epidemiology of infectious diseases of Spanish wild boars.     

The response of Mediterranean herbaceous community to soil disturbance by native wild boars

Native wild boar (Sus scrofa lybicus) populations in Israel increased in the last decades, and their rooting activity presents an apparent severe disturbance that may affect herbaceous plant communities. We studied the extent of wild boar rooting and its effect on herbaceous vegetation in an east Mediterranean garrigue. We compared the effects of rooting soil disturbance (RSD) between summer, winter, and RSD-free control plots on herbaceous plants. RSD affected four percent of the area covered by herbaceous vegetation in winter and spring, and only 2 % in summer. Summer RSD increased herbaceous species diversity in the following spring by decreasing the abundance of the dominant species, but it did not affect total herbaceous biomass. Winter RSD lowered herbaceous biomass but did not affect herbaceous plant abundance or diversity. We conclude that Mediterranean herbaceous plant community appears to be resilient to RSD, causing only minor changes in species composition and small decrease of their biomass. The contrast between the relatively large extent of wild boars RSD, and its limited impact on the herbaceous plant community, can be attributed to the long mutual evolutionary history of wild boars and these vegetation communities.