Visceral helminths of wild boars (Sus scrofa leucomystax) in Japan, with special reference to a new species of the genus Morgascaridia Inglis, 1958 (Nematoda: Schneidernematidae)

Twenty-nine Japanese wild boars (Sus scrofa leucomystax), collected during the hunting seasons of 2005 and 2006 in the western part of the mainland of Japan (Honshu), were examined for their visceral helminths. Eighteen helminth parasites were prevalent in them, including 17 Nematoda species (Metastrongylus elongatus, Metastrongylus salmi, Metastrongylus asymmetricus, Metastrongylus pudendotechus, Stephanurus dentatus, Gnathostoma doloresi, Physocephalus sexulata, Ascarops strongylina, Capillaria suis, Ascaris suum, Globocephalus samoensis, Globocephalus longimucronatus, Strongyloides ransomi, Trichuris suis, Bourgelatia diducta, Oesophagostomum dentatum, and Oesophagostomum watanabei), and one Cestoda species (Pseudanoplocephala nipponensis). Muscle digestion of the diaphragm (using an artificial gastric juice) of 24 wild boars detected a single diplostomulum of probably Pharyngostomum cordatum. In addition, four female and six male adults of Morgascaridia kugii sp. n. (Nematoda: Schneidernematidae) were recovered from the large intestine of a single wild boar. Examination of an additional 20 samples of the stomach and 27 samples of the large intestine could not find this species. To date, recorded species of the genus Morgascaridia are limited to M. sellsi collected from wild boars in Uganda and Congo several decades ago, and thence, no records of the recovery are available. Morgascaridia kugii sp. n. differed from M. sellsi by smaller body dimensions, shorter distance between the precloacal sucker and the cloaca, smaller sizes of the copulatory spicules and the gubernaculum, and smaller sizes of uterine eggs.     

Familial aggregation of human susceptibility to co- and multiple helminth infections in a population from the Poyang Lake region, China

Human helminthiases are common in China, especially in rural areas where sanitation conditions are poor. Co- and multiple infections with helminths are strikingly frequent. A cross-sectional parasitological and questionnaire survey was carried out in a population of 3205 individuals belonging to 498 families from five villages in the Poyang Lake region, Jiangxi Province, China, to assess their helminth infection status and to collect information on risk factors for infection. The prevalences for Ascaris lumbricoides, Schistosoma japonicum and Trichuris trichiura were 30.9%, 15.7% and 47%, respectively. Hookworm infection prevalence was low (0.7%). A significant association was observed between A. lumbricoides and T. trichiura infection, and also between S. japonicum and T. trichiura infection. Variance components analysis was undertaken to investigate the aggregation of S. japonicum and the soil-transmitted helminths, A. lumbricoides and T. trichiura. While A. lumbricoides was found to aggregate only at a household level, T. trichiura was shown to cluster predominantly in families. Both genetic and household effects were found to be important in determining the risk of infection with S. japonicum. Variance components analysis for A. lumbricoides/T. trichiura co-infections indicated a significant domestic environmental effect, attributable for 32.7% of the co-infection risk. Aggregation of S. japonicum/T. trichiura co-infection was also observed at a household level. The risk of infection with multiple helminth species, although mainly environmentally influenced, was also shown to have significant involvement of genetic and household components. The results of this study indicate that a shared household is a major contributing risk factor for helminth co-infections and emphasises the need for increased standards of sanitation and hygiene to prevent parasite transmission. Further, the results suggest that susceptibility to one helminth infection is not completely independent of another, and that there exist common genetic factors underlying infection with multiple helminth species.     

Helminth infections of wild boars (Sus scrofa) in the Bursa province of Turkey

The present study aimed to investigate the status of helminth infections in wild boars in the Bursa province of Turkey. For this purpose, during 2007-2008, 27 wild boars were necropsied and examined for helminths. Individual samples of tongue and diaphragm from 27 necropsied wild boars and an additional 22 tongue and diaphragm samples provided by hunters were examined by trichinoscopy and artificial digestion for Trichinella spp. larvae. Twenty animals (74%) were identified as being infected with at least one helminth species. Twelve species of helminths were detected, with the following prevalence rates: Metastrongylus apri (59%), Metastrongylus salmi (52%), Metastrongylus pudendotectus (52%), Dicrocoelium dendriticum (33%), Globocephalus urosubulatus (22%), Macracanthorhynchus hirudinaceus (19%), Gongylonema pulchrum (11%), Physocephalus sexalatus (7%), Trichuris suis (7%), Ascarops strongylina (4%), Hyostrongylus rubidus (4%) and Taenia hydatigena larvae (4%). Generally, lungworms were the predominant helminths. The highest mean abundance was observed for M. pudendotectus, and the lowest was determined for T. hydatigena larvae. Significant differences in the prevalence and intensity were found for D. dendriticum with respect to host age and sex, respectively. The mean intensity of M. pudendotectus was significantly influenced by the sex and age of the wild boars. This study is the first report describing the presence of M. salmi, M. pudendotectus, D. dendriticum, G. urosubulatus, M. hirudinaceus, P. sexalatus, A. strongylina and H. rubidus in wild boars in Turkey. All analysed muscle samples were negative for Trichinella spp. larvae.     

Helminths of wild boar in Spain.

Forty-seven wild boars (Sus scrofa) collected from two areas in the province of Valencia (eastern Spain) were examined for digestive and respiratory helminth parasites. Helminth species and their prevalence were Taenia hydatigena cysticercus (19%), Ascarops strongylina (87%), Physocephalus sexalatus (6%), Ascaris suum (2%), Metastrongylus spp. (85%), Capillaria sp. (2%) and Macracanthorhynchus hirudinaceus (21%). Trichinella spp. were not found. Physocephalus sexalatus, A. suum, Capillaria sp. and M. hirudinaceus were found only in wild boars collected from one area (National Hunting Reserve of Cortes de Pallás). Macracanthorhynchus hirudinaceus did not occur in hogs < 1-yr-old, whereas the intensity of Metastrongylus spp. infection was the greatest in this age group.     

Helminth parasites of the wild boar,Sus scrofa,in Luristan province,western Iran and their public health significance

Seven helminth species were obtained from 12 wild boars (Sus scrofa) during a survey from 2000 to 2001 in Luristan province, western Iran. These species include the cestode larvae Cysticercus tenuicollis (25%), C. cellulosae (8.3%), the nematodes Metastrongylus apri (41.6%), M. pudendotectus (16.6%), M. salmi (8.3%), Trichuris suis (8.3%) and the acanthocephalan Macracanthorhynchus hirudinaceus (41.6%). No trematodes were found. Seven wild boars (58.3%) were identified as having at least one helminth species. A single infection was detected in 16.6% of cases, but a three species infection covered the highest rank (25%). All these helminths have been reported from other areas of Iran including the north, northeast and southwest, but not in Luristan. Among seven helminths identified, at least three species are transmissible to humans. The public health significance of these helminths is discussed.     

Analysis of serum and whole blood values in relation to helminth and ectoparasite infections of feral pigs in Texas

In the summers of 1996 and 1997, 60 wild pigs (Sus scrofa) were necropsied from three sites in south Texas (USA) to test the hypothesis that serum and whole blood parameters vary significantly (P < or = 0.05) with the prevalence and intensity of parasites infecting wild pigs. We found ten parasite species: five nematodes (Metastrongylus salmi, Metastrongylus pudentotectus, Stephanurus dentatus, Oesophagostomum dentatum, and Physocephalus sexalatus); four ixodid ticks (Amblyomma cajennense, Amblyomma maculatum, Amblyomma americanum, and Dermacentor variabilis); and one trematode (Fascioloides magna). Among juvenile pigs, the intensity of the four species of ticks, collectively, was negatively correlated (P < or = 0.05) with whole blood principal component number one (PC-1); this factor was positively associated with lymphocytes and eosinophils. Lungworm intensity (Metastrongylus spp.) among adult pigs was negatively correlated (P < or = 0.05) with whole blood PC-2; this factor was negatively associated with segmented neutrophils and monocytes. There were no significant correlations found between parasite prevalences and either serum or whole blood principal component factors. The correlations observed between parasite intensities and serum and whole blood parameters generally were weak. Thus, we found no strong evidence that serum and whole blood parameters provided good predictive information on parasite infections in wild pigs for most practical management decisions.     

Visceral helminth communities of an insular population of feral swine

Nine species of helminths, all nematodes, were recovered from the viscera of 48 feral swine (Sus scrofa) from Cumberland Island, Georgia. Both the overdispersed frequency distributions and the abundances of the four common species of helminths (Stephanurus dentatus, Metastrongylus apri, M. pudendotectus and Gongylonema pulchrum) did not vary significantly across the main and interactive effects of host sex and/or seasons. Whether or not the present low population densities of feral swine on Cumberland Island has influenced the pattern of fluctuations in abundances of helminth species across seasons as often observed in helminth communities from other hosts was not resolved. The apparent recent decline in prevalences and abundances, and the loss of certain species from the helminth communities of feral swine on the island may be explained partially by the decreasing transmission potentials of direct life cycle species caused by a recent marked reduction of numbers of individuals in the host population. Conversely, the apparent increased prevalence and abundance of three species of helminths (S. dentatus, M. apri and M. pudendotectus) may be related to their common utilization of earthworms as paratenic or intermediate hosts. Gongylonema pulchrum was the only helminth in which abundances seemed to remain unchanged. This was the only species that was not strictly host specific to feral swine. We found no evidence that helminth infections were responsible for morbidity or mortality in this feral swine population.     

Intestinal helminthiases and schistosomiasis among school children in an urban center and some rural communities in southwest Nigeria

Intestinal helminths and schistosomiasis among school children were investigated in an urban and some rural communities of Ogun State, southwest Nigeria. Fecal samples of 1,059 subjects (524 males, 535 females) aged 3-18 years were examined using direct smear and brine concentration methods between June 2005 and November 2006. The pooled prevalence of infection was 66.2%. Ascaris lumbricoides showed the highest prevalence (53.4%) (P < 0.001) followed by hookworms (17.8%), Trichuris trichiura (10.4%), Taenia sp. (9.6%), Schistosoma mansoni (2.3%), Strongyloides stercoralis (0.7%), Schistosoma haematobium (0.6%), and Enterobius vermicularis (0.3%). The prevalences of A. lumbricoides, hookworms, Taenia sp., S. mansoni, and S. stercoralis in the urban centre were similar (P > 0.05) to those in the rural communities. The fertile and infertile egg ratios of A. lumbricoides in the urban centre and the rural communities were 13: 1 and 3.7: 1, respectively. Each helminth had similar prevalences among both genders (P > 0.05). The prevalence of A. lumbricoides increased significantly with age (P < 0.001). The commonest double infections were Ascaris and hookworms, while the commonest triple infections were Ascaris, hookworms, and Trichuris. The study demonstrates the need for urgent intervention programmes against intestinal helminthiases and schistosomiasis in the study area.     

Epidemiology of intestinal helminth parasites of dogs in Ibadan, Nigeria

An epidemiological study of gastrointestinal helminths of dogs (Canis familiaris) in two veterinary clinics in Ibadan, Nigeria, was conducted between January 2001 and December 2002. Faecal samples collected from 959 dogs were processed by modified Kato-Katz technique and then examined for helminth eggs. The results of the study showed that 237 (24.7%) of the dogs examined were infected with different types of helminths. The prevalences for the various helminth eggs observed were: Toxocara canis 9.0%, Ancylostoma spp. 17.9%, Toxascaris leonina 0.6%, Trichuris vulpis 0.5%, Uncinaria stenocephala 0.4% and Dipylidium caninum 0.2%. The faecal egg intensities, determined as mean egg count/gram of faeces ( +/- SEM), were: T. canis 462.0 +/- 100.5, Ancylostoma spp. 54.1 +/- 8.6, T. leonina 0.8 +/- 0.4, T. vulpis 0.1 +/- 0.0, U. stenocephala 1.0 +/- 0.7 and D. caninum 0.2 +/- 0.1. Host age was found to be a significant factor with respect to the prevalence and intensity of T. canis and Ancylostoma spp. There was no significant difference in the prevalence of intestinal helminth parasites between male (27.0%) and female (22.5%) dogs (P>0.05). The prevalence of helminth parasites was significantly higher (P < 0.05) in the local breed (African shepherd) (41.2%) than in Alsatian dogs (16.2%) or in other exotic breeds (21.0%). Single parasite infections (85.7%) were more common than mixed infections (3.5%).     

The pig as a host for Schistosoma mekongi in Laos.

A survey of helminths in domestic pigs was conducted in Khong District, Laos, to elucidate if these domestic animals could act as definitive hosts for Schistosoma mekongi and to obtain a general overview of their helminthological infection status. Fecal samples were collected from 98 pigs. Twelve pigs (12.2%) were found to excrete S. mekongi eggs. Infection was confirmed by detection of S. mekongi eggs in tissues of liver, rectum, and cecum of 2 pigs. A total of 75.8% of the pigs was infected with 1 or more helminth species. This study showed that pigs may act as a definitive host for S. mekongi.     

Bayesian estimation of community prevalences of Schistosoma japonicum infection in China

A Bayesian approach to overcome the imperfections of an immunological test (an antibody-based ELISA) and a parasitological test (Kato-Katz) in the detection of Schistosoma japonicum infection, was used to estimate community prevalences of S. japonicum infection in China. At the same time, the similarity between the prevalence estimates based on data from ELISA alone and those using data from both ELISA and Kato-Katz tests was explored. The database from the third nationwide sampling survey of schistosomiasis in China, 2004, was used for analysis, in which a total of 239 endemic villages were sampled from seven endemic provinces through a stratified cluster sampling technique and 250,987 residents aged from 6 to 65 years, were examined by ELISA followed by a Kato-Katz test applied to the seropositives. Bayesian hierarchical models incorporating random effects to reflect the nested data structure and uncertainty about test properties were employed to analyse the data. Our analysis suggested that using data from ELISA alone or both ELISA and Kato-Katz tests resulted in similar prevalence estimates, probably owing to the lack of sensitivity of Kato-Katz and the fact that Kato-Katz was only applied to the seropositives. We conclude that it is feasible to employ only ELISA, instead of combined ELISA and Kato-Katz tests, to estimate prevalence of S. japonicum infection in large-scale epidemiological settings. This study confirmed heterogeneity in the prevalence of S. japonicum infection in space by the fact that the estimated prevalences of S. japonicum infection in the sampled villages ranged from 0.02% to about 56% (posterior median). It is indicated that the disease remains a threat in some areas along the Yangtze River, although great achievements have been made in the control programme of schistosomiasis in China.     

Helminths of red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) in Lithuania

Red foxes and raccoon dogs are hosts for a wide range of parasites including important zoonotic helminths. The raccoon dog has recently invaded into Europe from the east. The contribution of this exotic species to the epidemiology of parasitic diseases, particularly parasitic zoonoses is unknown. The helminth fauna and the abundance of helminth infections were determined in 310 carcasses of hunted red foxes and 99 of raccoon dogs from Lithuania. Both species were highly infected with Alaria alata (94·8% and 96·5% respectively) and Trichinella spp. (46·6% and 29·3%). High and significantly different prevalences in foxes and raccoon dogs were found for Eucoleus aerophilus (97·1% and 30·2% respectively), Crenosoma vulpis (53·8% and 15·1%), Capillaria plica (93·3% and 11·3%), C. putorii (29·4% and 51·5%), Toxocara canis (40·5% and 17·6%) and Uncinaria stenocephala (76·9% and 98·8%). The prevalences of the rodent-transmitted cestodes Echinococcus multilocularis, Taenia polyacantha, T. crassiceps and Mesocestoides spp. were significantly higher in foxes than in raccoon dogs. The abundances of E. multilocularis, Mesocestoides, Taenia, C. plica and E. aerophilus were higher in foxes than those in raccoon dogs. A. alata, U. stenocephala, C. putorii and Echinostomatidae had higher abundances in raccoon dogs. The difference in prevalence and abundance of helminths in both animals may reflect differences in host ecology and susceptibility. The data are consistent with red foxes playing a more important role than raccoon dogs in the transmission of E. multilocularis in Lithuania.     

Schistosomiasis in Indonesia: past and present

Schistosomiasis is endemic in Indonesia in two isolated areas, Lindu valley and Napu valley, both located in the Province of Central Sulawesi. In 1940, a prevalence survey was initiated in Lake Lindu, which indicated a Schistosoma japonicum infection prevalence of 56% among the population of Anca, Tomado and Langko villages. Another survey was conducted in 1973 in Napu valley and very high infection prevalences of up to 72% were found among the population in Winowanga village. Since then, comprehensive studies on the epidemiology and the effects of control have been carried out in 24 endemic villages in both areas. Over the past six decades, schistosomiasis control has been implemented and the average prevalence is now much lower than before the control programme was launched. In 2006, it was 0.49% in 7 villages in Lindu valley. In Napu valley, the average infection prevalence among the population of 17 villages was 1.08% in the same year. Again in 2006, the prevalence of infection in snails ranged from 0 to 13.4% and from 0 to 9.1% in Napu and Lindu valleys, respectively. The highest prevalence among snails was found in Dodolo village. The prevalence of S. japonicum in the reservoir host Rattus spp. ranged from 0 to 20% and the highest prevalence was again found in Dodolo village. Contemporary data suggest that transmission of schistosomiasis is still ongoing in Indonesia despite regular surveillance and control activities covering the whole endemic area.     

Abomasal nematodes of the red deer Cervus elaphus in north-eastern Italy

The composition of the abomasal helminth fauna and parasite diversity were studied in 298 red deer collected during 1997-2000 from three different sectors (Bolzano, Trento and Sondrio provinces) of the Stelvio National Park, one of the main protected areas of north-eastern Italy. The association between parasite burdens and geographical areas of the hosts was assessed using the negative binomial regression. A variety of abomasal helminths, both host specific and generalist, was found in all sectors. The most commonly observed parasites were the Spiculopteragia spiculoptera morph spiculoptera and Ostertagia leptospicularis morph leptospicularis, with prevalences of 79.5% and 40.9%, respectively. The minor morphs S. spiculoptera morph mathevossiani (prevalence 31.9%) and O. leptospicularis morph kolchida (18.8%) occurred at lower prevalences. Teladorsagia circumcincta morph circumcincta, Marshallagia marshalli morph marshalli and Haemonchus contortus were rarer, at prevalences of 1, 1.3 and 1.3%, respectively. Deviance analysis of the negative binomial regression model shows that the geographical area is significantly related to parasite burdens (P = 0.001). Prevalences of hosts with parasites were greater in the Sondrio (odds ratio = 1.31; 95% confidence interval: 0.16-10.85) and smaller in the Trento (odds ratio = 0.62; 95% confidence interval: 0.20-1.96) sectors with respect to Bolzano, but these differences were not statistically significant. Possible cross-infections by more generalist parasites between wild and domestic animals were also suggested, as deer and domestic ruminants (Bovinae, Caprinae and Ovinae) used the same feeding areas of the park sectors.     

Plasmodium/intestinal helminth co-infections among pregnant Nigerian women.

Hospital based studies were conducted to investigate the occurrence of Plasmodium/intestinal helminth co-infections among pregnant Nigerian women, and their effects on birthweights, anaemia and spleen size. From 2,104 near-term pregnant women examined, 816 (38.8%) were found to be infected with malaria parasites. Among the 816 parasitaemic subjects, 394 (48.3%) were also infected with intestinal helminths, 102 (12.5%) having mixed helminth infections. The prevalence of the helminth species found in stool samples of parasitaemic subjects examined was, Ascaris lumbricoides (19.1%), hookworm (14.2%), Trichuris trichiura (7%) Schistosoma mansoni (3.4%), Enterobius vermicularis (2%), Hymenolepis sp. (1.6%) and Taenia sp. (1%). Mothers with Plasmodium infection but without intestinal helminth infection had neonates of higher mean birthweights than those presenting both Plasmodium and intestinal helminth infections and this effect was more pronounced in primigravids. The mean haemoglobin values of malarial mothers with intestinal helminth infections were lower than those with Plasmodium infection but without intestinal helminth infections but these were not statistically significant. Severe splenomegaly was predominant among parasitaemic gravidae who also harboured S. mansoni infection in two of the hospitals studied.     

Characterization of Sm14 related components in different helminths by sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis

Sm14 was the first fatty acid-binding protein homologue identified in helminths. Thereafter, members of the same family were identified in several helminth species, with high aminoacid sequence homology between them. In addition, immune crossprotection was also reported against Fasciola hepatica infection, in animals previously immunized with the Schistosoma mansoni vaccine candidate, r-Sm14. In the present study, data on preliminary sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blotting analysis of nine different helminth extracts focusing the identification of Sm14 related proteins, is reported. Out of these, three extracts - Ascaris suum (males and females), Echinostoma paraensei, and Taenia saginata - presented components that comigrated with Sm14 in SDS-PAGE, and that were recognized by anti-rSm14 policlonal serum, in Western blotting tests.     

Schistosoma mansoni and Schistosoma japonicum: comparison of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in adults.

Glucose-6-phosphate dehydrogenase activity in paired adult Schistosoma mansoni is about twice as great as in paired adult Schistosoma japonicum. 2. 6-phosphogluconate dehydrogenase activity accounts for 25.8% of the measured production of reduced nicotinamide adenine dinucleotide phosphate (NADPH) in S. japonicum but only 8.6% of the measured production of NADPH in S. mansoni. 3. These data suggest a species difference in 6-phosphogluconate metabolism.     

Nose-Rings and Transmission of Helminth Parasites in Outdoor Pigs

Five growing pigs experimentally infected with low doses of Oesophagostomum dentation, Ascaris suum, and Trichuris suis were turned out with 5 helminth-naïve pigs on each of 3 pastures in June 1996 (Group 1). On one pasture all pigs received nose-rings. After slaughter of Group 1 in October, pasture infectivity was monitored using helminth-naïve, unringed tracer pigs. In 1997, helminth-naïve young pigs were turned out on the contaminated pastures in May (Group 2) and again in August (Group 3). Again all pigs on one pasture received nose-rings. All pigs and pastures were followed parasitologically and reduction in grass cover was monitored. Based on the acquisition of infection by the naïve pigs in Group 1, the estimated minimal embryonation times for eggs deposited on pasture were 23–25 days for O. dentatum, 5–6 weeks for A. suum and 9–10 weeks for T. suis. Results from tracer pigs and grass/soil samples indicated that pasture infectivity was light both years. Free-living stages of O. dentatum did not survive the winter. The nose-rings reduced rooting considerably, resulting in three-fold more grass cover on the nose-ring pasture compared to the control pastures by the end of the experiment. Nevertheless, the nose-rings did not significantly influence parasite transmission.     

An insight into the genetic variation of Schistosoma japonicum in mainland China using DNA microsatellite markers

This study presents the first microsatellite investigation into the level of genetic variation among Schistosoma japonicum from different geographical origins. S. japonicum isolates were obtained from seven endemic provinces across mainland China: Zhejiang (Jiashan County), Anhui (Guichi County), Jiangxi (Yongxiu County), Hubei (Wuhan County), Hunan (Yueyang area), Sichuan 1 (Maoshan County), Sichuan 2 (Tianquan County), Yunnan (Dali County), and also one province in the Philippines (Sorsogon). DNA from 20 individuals from each origin were screened against 11 recently isolated and characterized S. japonicum microsatellites, and a set of nine loci were selected based on their polymorphic information content. High levels of polymorphism were obtained between and within population samples, with Chinese and Philippine strains appearing to follow different lineages, and with distinct branching between provinces. Moreover, across mainland China, genotype clustering appeared to be related to habitat type and/or intermediate host morph. These results highlight the suitability of microsatellites for population genetic studies of S. japonicum and suggest that there may be different strains of S. japonicum circulating in mainland China.     

Health status of a recently discovered population of feral swine in Kansas.

Twenty feral hogs (Sus scrofa) from a newly discovered population on Fort Riley Army Base (Kansas, USA) were shot and examined from November 1993 through February 1994 to assess the health of the population. The hogs were generally healthy, although serologic evidence indicated that some individuals had been exposed to parvovirus, enterovirus, and swine influenza. We found no indications of brucellosis, pseudorabies, or porcine respiratory and reproductive syndrome. Lung worms (Metastrongylus spp.), round worms (Ascaris suum), and whipworms (Trichuris suis) were found in nine, four and two of the hogs, respectively. Seven hogs had infestations of lice (Haematopinus suis). Fence-line contacts were documented between four wild boars and domestic sows, and in three cases wild boars entered pens containing domestic sows. We recommend that hogs be examined periodically from this and other wild populations to monitor health status since new animals may enter populations through deliberate translocation, escape from shooting preserves or domestic swine producers, or dispersal from other feral populations.