Spatial distribution of Trichinella britovi, T. spiralis and T. pseudospiralis of domestic pigs and wild boars (Sus scrofa) in Hungary

Trichinellosis is a foodborne disease caused by the consumption of raw meat and raw meat-derived products from swine, horse and some game animals infected with nematode worms of the genus Trichinella. Between June 2006 and February 2011, 16 million domestic pigs and 0.22 million wild boars (Sus scrofa) were tested for Trichinella sp. in Hungary. Trichinella infection was not found in any pigs slaughtered for public consumption. Nevertheless, Trichinella spiralis was detected in four backyard pigs when trace back was done following a family outbreak. Trichinella infection was demonstrated in 17 wild boars (0.0077%). Larvae from wild boars were identified as Trichinella britovi (64.7%), T. spiralis (29.4%) and Trichinella pseudospiralis (5.9%). Although the prevalence of Trichinella sp. infection in wild boars and domestic pigs is very low, the spatial analysis reveals that the level of risk differs by region in Hungary. Most of the T. britovi infected wild boars (63.6%) were shot in the north-eastern mountain area of Hungary; whereas domestic pigs and wild boars infected with T. spiralis were detected only in the southern counties bordering Croatia and Romania. In the north-western and central counties, the prevalence of Trichinella infection seems to be negligible.     

Prevalence of anti-Toxoplasma gondii antibody in hunter-killed wild boars, Sus scrofa leucomystax, on Amakusa Island, Kumamoto Prefecture, Japan

The prevalence of Toxoplasma gondii was surveyed in wild boars (Sus scrofa leucomystax) and domiciled cats obtained in various areas of Amakusa Island, Kumamoto Prefecture, Japan. The antibody titers against T. gondii were measured with a latex agglutination test. Among specimens taken from 90 wild boars, 1 (1.1%) was positive and 3 (3.3%)were doubtfully positive. Among the specimens from 50 cats, none were positive and 1 (3.3%) was doubtfully positive. These results suggest that the wild boars and cats on Amakusa Island have quite low prevalence of the T. gondii infection. Continuous surveys will be needed to monitor the prevalence of Toxoplasmosis and other zoonoses in game animals.     

Trichinella pseudospiralis foci in Sweden

In Sweden, the prevalence of Trichinella infection in domestic pigs has greatly decreased since the 1970s, with no reports in the past 4 years. However, infected wild animals continue to be found. The objective of the present study was to identify the species of Trichinella present in animals of Sweden, so as to contribute to the knowledge on the distribution area and hosts useful for the prevention and control of this zoonosis. In the period 1985-2003, Trichinella larvae were detected in the muscles of 81/1800 (4.5%) red foxes (Vulpes vulpes), 1/6 (16.7%) arctic fox (Alopex lagopus), 1/7 (14.3%) wolf (Canis lupus), 10/200 (5.0%) lynxes (Lynx lynx), 4/8000 (0.05%) wild boars (Sus scrofa), and 27/66 x 10(6) (0.000041%) domestic pigs. All four Trichinella species previously found in Europe were detected (Trichinella spiralis, T. nativa, T. britovi and T. pseudospiralis). The non-encapsulated species T. pseudospiralis was detected in three wild boars from Holo (Stockholm area) and in one lynx from Froso (Ostersund area), suggesting that this species is widespread in Sweden. These findings are consistent with those of a study from Finland, both for the unexpected presence of T. pseudospiralis infection and the presence of the same four Trichinella species, suggesting that this epidemiological situation is present in the entire Scandinavian region. The widespread diffusion of T. pseudospiralis in the Scandinavian region is also important in terms of it potential impact on public health, given that human infection can occur and the difficulties to detect it by the trichinelloscopic examination.     

Prevalence of Trichinella spp. in red foxes and wild boars in the northwestern part of Poland

The aim of the study was to establish in which degree wild boars and red foxes are reservoir of Trichinella spp. in North-West Poland. Research was carried out between 1997 and 2004 on 505 foxes and 56,462 wild boars in muscle samples. The muscle samples were examined using the digestion method. The average prevalence rate of Trichinella spp. infection of foxes was 4.4 %. Large differences of the infection rate in wild boars were observed. In the years 1999-2001 Trichinella spp. larvae were observed in 58 animals (0.2 %) and between 2002 and 2004 the Trichinella spp. prevalence in 227 wild boars was 0.9 %, demonstrating that the animals were 5.1 times more often infected than in 1999-2001. The growth of red fox population after the oral vaccination against rabies was probably the cause of this phenomenon.     

Prevalence of Toxoplasma gondii and Neospora caninum antibodies in wild boars in the Czech Republic

Sera collected from hunter-killed wild boars (Sus scrofa) during 1999-2005 from seven different regions of the Czech Republic were assayed for antibodies to Toxoplasma gondii by indirect fluorescence antibody test and to Neospora caninum by competitive-inhibition enzyme-linked immunosorbent assay and by indirect fluorescence antibody test. Antibodies to T. gondii were detected in 148 (26.2%) of 565 wild boars with serum dilutions of 1:40 in 40, 1:80 in 40, 1:160 in 27, 1:320 in 19, 1:640 in 18 and 1:1280 in 4 wild boars. Antibodies to N. caninum were detected in 102 (18.1%) of 565 wild boars with 30.1-94.6% inhibition in ELISA; statistical significant differences were observed between sampling regions, ranging from 0% to 31.8%. Sera, positive in ELISA, were examined in IFAT; 58 of 102 (56.9%) were positive with titres 1:40-1:160. Mixed infection (concurrent presence of both T. gondii and N. caninum antibodies) was found in 38 wild boars. It is the first report of antibodies to N. caninum in wild boar. Serological results indicate a common exposure to T. gondii and to N. caninum among wild boars in the Czech Republic.     

Prevalence of Cryptosporidium and Giardia in roe deer (Capreolus capreolus) and wild boars (Sus scrofa) in Galicia (NW, Spain)

Faecal samples from 224 roe deer (Capreolus capreolus) and 381 wild boars (Sus scrofa) shot during the 2008-2009 hunting season (August-January) in Galicia (NW Spain) were examined to determine the presence and intensity of infection by Cryptosporidium and Giardia. Analysis of a single sample from each of the roe deer revealed that the prevalence of cryptosporidiosis and giardiosis was 1.3% and 5.3% respectively. The prevalence of Giardia infection was significantly higher in juvenile female roe deer than in adult females, but no other significant differences were found in relation to age and sex. In wild boars, the prevalence of cryptosporidiosis and giardiosis was 7.6% and 1.3% respectively. The prevalence of Cryptosporidium infection was significantly higher in juvenile male wild boars than in adult males, but no other significant differences were found in relation to age or sex. In both groups of wild animals, the number of Cryptosporidium oocysts per gram of faeces (OPG) ranged from 5 to 200 and the number of Giardia cysts per gram of faeces (CPG) was between 5 and 47; there were no significant differences between the two groups with respect to number of infections. This is the first large study of Cryptosporidium and Giardia in roe deer and wild boars in hunting areas in Spain and the results demonstrate a low, but widespread prevalence of Cryptosporidium and Giardia in these animals.     

Autochthonous and imported Trichinella isolates in Germany

The study of Trichinella isolates from wildlife in Germany revealed the presence of Trichinella spiralis and Trichinella britovi in wild boars and foxes. T spiralis was detected in meat products imported from Spain, which is one of the two endemic areas of domestic trichinellosis in the European Union: It was also detected in meat from a grizzly bear marketed in Alaska, and Trichinella nativa was detected in a polar bear from the Berlin Zoo. These results stress the importance of examining for Trichinella live animals and meat products imported to Germany from both EU and non-EU countries. Furthermore, carnivores from Arctic regions that are born in the wild and placed in zoos can represent a risk for the introduction of the freeze-resistant species of Trichinella in a new region if, once the animal dies, the carcass is not properly destroyed.     

Characterisation of Trichinella isolates from Bulgaria by molecular typing and cross-breeding

Trichinella spp. larvae were collected from domestic and wild-life animals in association with 15 human trichinellosis outbreaks registered between 1999-2002 in Bulgaria. Furthermore, Trichinella spp. isolates were obtained from 62 naturally infected wild animals and of a rat. All isolates were subjected to speciation by both multiplex PCR and cross-breeding experiments. Epidemiological and clinical data were collected and analysed using standard protocols for epidemiological surveillance and control of outbreaks. Only two species were identified-Trichinella britovi and Trichinella spiralis. Results obtained by molecular typing fully matched those of cross-breeding. More specifically, parasite isolates obtained upon 15 epidemic outbreaks revealed the predominance of T. britovi (n = 10) when compared to T. spiralis (n = 5). With regard to host origin, the predominant species detected among wild boar was T. britovi (n = 4), and T. spiralis was identified in one wild boar sample only. Among the isolates obtained from domestic pig products, T. britovi was found in five cases and T. spiralis in four cases, respectively. In the naturally infected wild animals not related to epidemics, only T. britovi was demonstrated. The present results provide a strong indication that both T. britovi and T. spiralis operate within domestic and sylvatic cycles in Bulgaria. Geographically, the distribution of T. britovi appears to include Central, Southern, Eastern and Western parts of the country, and wildlife animals from the Mid Balkan Mountains and Mid Sredna Gora Mountains, T. spiralis was found in Western and Southwestern Bulgaria, only.     

Antibody response against Trichinella spiralis in experimentally infected rats is dose dependent

ABSTRACT: Domestic pigs are the main representatives of the domestic cycle of Trichinella spiralis that play a role in transmission to humans. In Europe, backyard pigs of small household farms are the most important risks for humans to obtain trichinellosis. Rats might play a role in the transmission of Trichinella spiralis from domestic to sylvatic animals and vice versa. In order to be able to investigate the role of wild rats in the epidemiology of T. spiralis in The Netherlands, we studied the dynamics of antibody response after T. spiralis infections in experimental rats, using infection doses ranging from very low (10 muscle larvae, ML, per rat) to very high (16 000 ML per rat). To evaluate the feasibility of rats surviving high infection doses with T. spiralis, clinical and pathological parameters were quantified. Serological tools for detecting T. spiralis in rats were developed to quantitatively study the correlation between parasite load and immunological response. The results show that an infection dose-dependent antibody response was developed in rats after infection with as low as 10 ML up to a level of 10 000 ML. A positive correlation was found between the number of recovered ML and serum antibody levels, although specific measured antibody levels correspond to a wide range of LPG values. Serum antibodies of rats that were infected even with 10 or 25 ML could readily be detected by use of the T. spiralis western blot 2 weeks post infection. We conclude that based on these low infection doses, serologic tests are a useful tool to survey T. spiralis in wild rats.     

First isolation of Trichinella britovi from a wild boar (Sus scrofa) in Belgium

Since 1992, when the European Union Council Directive requires that wild boars (Sus scrofa) hunted in EU for commercial purpose should be examined for Trichinella, the infection has not been detected in wild boars from Belgium, despite serological evidence of the presence of anti-Trichinella antibodies in wildlife and previous reports of Trichinella larvae in this host species. In November 2004, Trichinella larvae were detected in a wild boar hunted near Mettet, Namur province (Southern Belgium). Larvae were identified as Trichinella britovi by polymerase chain reaction methods. This is the first report of the identification of Trichinella larvae from Belgium at the species level. The detection of T. britovi in wildlife in Belgium is consistent with findings of this parasite in other European countries and confirms the need to test game meat for Trichinella to prevent its transmission to humans.     

Experimental infection of European wild boars and domestic pigs with pseudorabies viruses with differing virulence

OBJECTIVE: To determine susceptibility of European wild boars (Sus scrofa) to infection with pseudorabies virus (PrV) and to characterize the virulence of a wildboar PrV isolate for wild and domestic pigs. ANIMALS: 18 wild boars and 16 domestic pigs. PROCEDURE: Three groups of 4 wild boars were inoculated with PrV Bartha, Kaplan, and a wild-boar isolate (BFW1) and housed with uninfected pigs. Two groups of domestic pigs (4 and 8 pigs/group, respectively) were inoculated with various doses of BFW1. Animals were observed daily for clinical signs, and samples were tested for PrV excretion and homologous antibodies. After reactivation of latent infection by induced immunosuppression, PrV was detected in tissues of necropsied animals, using cell culture and a polymerase chain reaction (PCR). RESULTS: Clinical signs depended on virulence of the PrV strain and dose of inoculum. Only infection with PrV Kaplan resulted in severe disease and death. Virus was isolated from nasal and genital swab specimens. Antibodies were first detected on day 7 after inoculation; a specific humoral immune response was delayed in BFW1-infected animals. Virus was isolated from various tissues of Kaplan-infected wild boars, whereas mainly viral DNA was detected in a few tissues of Bartha- and BFW1-infected animals, using PCR after immunosuppression. CONCLUSIONS AND CLINICAL RELEVANCE: European wild boars are susceptible to transmission of PrV infection from domestic pigs and vice-versa. The PrV isolate BFW1 is of low virulence and seems to be adapted to the wild boar population from which it was isolated.     

Trichinosis in a herd of swine: cannibalism as a major mode of transmission

In a herd of approximately 1,000 hogs, evaluation of muscle specimens collected at various intervals during a 12-year period (1973 to 1985) indicated continuous transmission of Trichinella spiralis. The farm's rat population and the incidence of trichinosis in the rats was high during 1974, but diminished markedly by 1978. In January 1984, a longitudinal investigation, using tracer pigs, was performed to determine whether rodents and/or other wild animals were involved in transmission of T spiralis on this farm. Tracer pigs exposed to rodents and wild animals did not become infected with T spiralis. The rodent population on the farm was small and none of the rodents trapped and examined were found to be infected. Hog cannibalism also was evaluated as a mode of T spiralis transmission. Results of the investigation indicated that hog cannibalism was the mode of transmission for trichinosis in the herd.     

The high prevalence of hepatitis E virus infection in wild boars in Ibaraki Prefecture,Japan

Hepatitis E virus (HEV) is known as a causative agent of zoonosis and food poisoning. Pigs and some species of wild animals, including wild boar, are known to be a reservoir of HEV. In this study, we investigated the situation regarding HEV infection in wild boars in Ibaraki Prefecture, Japan. Serum, liver and feces samples from 68 animals were collected, and the presence or absence of HEV genomic RNA and HEV antibodies were analyzed. The viral genome was detected in samples from 7 (10.3%) animals, with all HEVs classified as genotype 3, subtype 3b. HEV antibodies were detected in samples from 28 (41%) animals. This report demonstrates for the first time the high prevalence of HEV infection in wild boars in Ibaraki Prefecture.     

Detection of Lawsonia intracellularis in wild boar and fallow deer bred in one game enclosure in the Czech Republic

The prevalence of Lawsonia intracellularis between wild boar (Sus scrofa) and fallow deer (Dama dama) bred in one game reserve was investigated using the nested PCR method. In the study, 88 clinically healthy wild boars of different age categories and two fallow deer bagged in the game reserve were examined. Lawsonia intracellularis was demonstrated in the mucous membrane of the intestine of eight (9.1%) wild boars and one fallow deer. Of the nine wild boar whose tissues of corresponding lymph nodes were examined in addition to the mucous membrane of the ileum, one tested positive for the microorganism. A relationship between the occurrence of L. intracellularis and age of wild boar was demonstrated. Because wild boar and fallow deer are bred together in one game reserve, the possibility of inter-species transfer of L. intracellularis should be borne in mind.     

Epidemiological study on porcine circovirus type 2 (PCV2) infection in the European wild boar (Sus scrofa)

Porcine circovirus type 2 (PCV2) is considered as the causative agent of postweaning multisystemic wasting syndrome (PMWS) in domestic pigs, where the virus is ubiquitous as evidenced by serological surveys. We present the results of the first nationwide sero-survey on the presence of PCV2 antibodies in European wild boars, and report the first PMWS case in a wild boar from Spain. Sera from 656 hunter harvested wild boars from 45 different geographical sites and 22 additional imported animals were analysed by means of an immunoperoxidase monolayer assay (IPMA). We also examined the tissues from 55 healthy and one diseased wild boars for the presence of PCV2 nucleic acid and PMWS lesions by in situ hybridisation and histopathology, respectively. Additionally, abundance estimates of wild boars and field interviews were carried out on 30 sampling sites. The prevalence of medium to high PCV2 serological titres among the examined wild boars was 47.89 +/- 1.9%. Seropositive wild boars appeared in all but one of the geographical regions analysed. Seroprevalence and titre of PCV2 antibodies were closely related to the management of the wild boar populations. Wild boars from intensively managed, farm-like populations had higher prevalence than wild boars living in more natural situations. The effect of wild boar abundance and management on PCV2 antibody prevalence was further evidenced by the high correlation existing between the relative abundance estimates of animals and the percentage of wild boars with medium to high levels of PCV2 antibodies. PCV2 nucleic acid was detected in the tissues of three wild boars. One of these was diagnosed as PMWS. The results, in addition to information on piglet mortalities, suggest a potential role of PMWS in piglet mortality in intensively managed wild boar populations.     

Brucellosis and Aujeszky's disease in a wild boar enclose. Case report

In wild boars kept in a paddock of approximately 1.7 square miles Brucella suis biotype 2 was isolated and Aujeszky's disease was diagnosed by serological tests. To clear the paddock, the wild boars were lured by offered food and caught using specially built smaller pens. They were then transported to a location far off their original surroundings and euthanized. Of a total of 297 wild boars kept in the paddock, 71% were caught and 28% shot. Three wild boars (= 1%) were found trapped. The described method could also be used in case of epidemics to catch wild boars living outside existing paddocks. In order to avoid killing the boars which stayed in separate quarantine enclosures, a darting gun was used to anaesthetize the animals with tiletamine/zolazepam. Achieved sedation levels were deep enough to allow for blood samples to be taken from the jugular vein without any problems, i.e. without any defence reactions of the boars. The origin of infection could not be identified.     

Investigations with enzyme-linked immunosorbent assays for Trichinella spiralis and Toxoplasma gondii in the Dutch 'Integrated Quality Control for finishing pigs' research project.

In the framework of the Dutch field trial 'Integrated Quality Control (IQC) for finishing pigs' ELISA (screening) techniques were used to detect animals seropositive for Toxoplasma gondii and/or Trichinella spiralis. The aim was to determine whether farms which consistently delivered seropositive pigs could be detected and monitored (defined as 'problem farms'). The investigation involved 120 farms and three slaughterhouses, and a total of 23,348 serum samples were examined. In addition, all pigs were also screened for the presence of Trichinella spiralis with the digestion method (pooled samples). The prevalence of seropositivity for Trichinella spiralis and Toxoplasma gondii was 0.3% and 2.1% respectively. Parasitological examinations concerning T. spiralis were negative. Considering the characteristics of the used methodology, the conclusion was drawn that there were no parasitological or serological indications for T. spiralis infections, and that with respect to T. gondii the infection rate seemed to be equally low for all farms involved. In addition, a longitudinal pilot study during a whole finishing period was undertaken at two finishing farms. Animals seropositive for Toxoplasma gondii were found from the earliest days of the finishing period. Housing and management may (still) play an important role in the prevention of contact with this parasite.     

Seroprevalence of Toxoplasma gondii in free-ranging wild boars hunted for human consumption in Estonia

Background

Although the prevalence of human Toxoplasma gondii infections is high in Estonia, no information is available on the prevalence of infections in the local animal populations. Wild boars are a good indicator species for estimating the prevalence and spread of T. gondii and were thus investigated in this nationwide cross-sectional study. Volunteer hunters sampled cardiac or skeletal muscle of 471 wild boars legally hunted for human consumption in Estonia during the hunting season of 2012–2013. Serosanguineous meat juice samples were obtained from thawed tissue samples, diluted 1:40, and screened for specific anti-T. gondii IgG antibodies with a commercial direct agglutination test.

Results

Almost one-quarter (113; 24%) of the wild boars examined were seropositive for T. gondii. The seroprevalence did not differ significantly between age groups or sexes. The seroprevalence was lowest in Viljandimaa, which is located in the southern part of Estonia. In other counties, the infection was evenly prevalent.

Conclusions

In Estonia, wild boars are commonly exposed to T. gondii, which is endemic and widespread. The consumption of raw or undercooked meat of Estonian wild boars may pose an infection risk to humans and other hosts.     

Wild boar helminths: risks in animal translocations

The helminth populations found in a group of wild boars collected in central Spain were compared to those in a group of animals imported from a French game farm that produces boars for restocking. Eleven helminth species, including ten nematodes and one acanthocephalan, were found. Gongylonema pulchrum and Macracanthorhynchus hirundinaceus were only detected in autochthonous wild boars, while Oesophagostomum dentatum, Ascaris suum, and Trichuris suis were detected in imported animals only. Autochthonous wild boars were more frequently and more intensely parasitised by Ascarops strongylina than the imported ones. No differences in prevalence nor intensity were found for the species Capillaria garfiai, Globocephalus urosubulatus, Metastrongylus sp., Physocephalus sexalatus and Simondsia paradoxa. To our knowledge, G. urosubulatus, G. pulchrum and S. paradoxa have not previously been described in wild boars in Spain. Our results highlight the risks of translocating wild animals, with regard to their helminth parasites. Until improved control measures are established, it would be wise to avoid long-distance translocations in order to prevent the potential introduction of foreign parasites.     

PCR检测感染早期小鼠血液中旋毛虫幼虫的研究

为了研究PCR检测感染小鼠血液中旋毛虫DNA的敏感性,应用旋毛虫1.6 kb重复序列为扩增靶序列对旋毛虫(T1)、乡土旋毛虫(T2)、布氏旋毛虫(T3)、伪旋毛虫(T4)和南方旋毛虫(T7)肌幼虫DNA进行PCR扩增,并检测小鼠感染20、100、300条T1肌幼虫后不同时间的外周血.结果表明,T1、T4和T7肌幼虫可扩增出特异性目的条带(510 bp),而T2和T3无扩增产物;1、0.04和0.02条T1、T4和T7肌幼虫均能扩增到清晰的目的条带(510 bp).20条幼虫感染小鼠后5 d～6 d,PCR阳性率均为7.69%;100条幼虫感染小鼠后5 d～12 d可检出旋毛虫DNA,其中感染后5 d～7 d的阳性率分别为30.77%、38.46%及30.77%;300条幼虫感染小鼠后5 d～15 d可检出旋毛虫DNA,感染后7 d的阳性率为61.54%,感染后6 d与8 d～10 d的阳性率均为53.85%. 3组旋毛虫感染小鼠PCR阳性率间的差异有统计学意义(p<0.01),PCR阳性率随感染剂量的增加而升高(p<0.01),100条与300条感染小鼠感染后不同时间的PCR阳性率与检测时间有相关性(p<0.01).以上实验结果表明PCR检测感染小鼠血液中旋毛虫DNA的敏感性与感染程度和检测时间有关,对感染早期旋毛虫抗体阴性宿主有一定诊断价值.