Seroepidemiology of trichinellosis in Florida swine

Surveys for swine trichinellosis, conducted in Florida using a commercial enzyme-linked immunosorbent assay (ELISA) kit with a modified protocol for screening and Western blot as a definitive test, revealed significantly different seroprevalences of 0.3% (four of 1294 samples) and 2.8% (five of 179 samples) in domestic breeding swine and feral swine, respectively.

Seropositive swine were identified in four of 114 (3.5%) domestic swine herds and in three of six feral swine regions. The location of two domestic herds with seropositive swine within approximately 2 miles of one another, and adjacent to a region where a seropositive feral hog was identified, suggests that a focus of trichinellosis exists in this area. The occurrence of singleton reactors in domestic herds may be explained by the absence of the common modes of transmission and suggests that swine were infected incidentally by feeding on the infected carcasses of small wild mammals or rodents. Although the presence of Trichinella spiralis spiralis isolates cannot be excluded, it is more likely that a sylvatic Trichinella isolate occurs in Florida swine. This conclusion is supported by the low seroprevalence in domestic swine, the failure to detect larvae in domestic or feral swine and the high prevalence in Florida panthers.     

Prevalence of sparganosis by county of origin in Florida feral swine

Sparganosis is a parasitic infection in amphibians, reptiles and mammals including feral swine and man. It is caused by migration of the metacestode (spargana) of Spirometra. The primary objective of this study was the determination of the prevalence of gross sparganosis in Florida county of origin in slaughtered feral swine. Tracebacks to county of origin were conducted for Florida feral swine with and without gross sparganosis. Feral swine trapped in Florida and presented for slaughter in a Texas slaughter establishment from May to December 1999 was the sample population.Overall prevalence of sparganosis in Florida feral swine was 6.9%. Because Highlands county had the same prevalence, other counties were compared to it. Sparganosis was detected in 17 Florida counties. Swine originating from Osceola or Hillsborough counties (4.3 and 1.8% prevalence, respectively) had lower prevalence of sparganosis than in Highlands, whereas those from Marion county (21.7% prevalence) had a higher prevalence.Transmission to humans may occur via consumption of infected feral swine, other species of secondary intermediate hosts or the primary intermediate hosts.     

Impact of baiting on feral swine behavior in the presence of culling activities

We studied the effects of baiting on feral swine (Sus scrofa) movements and corresponding likelihood of disease spread under real and simulated culling pressure. Our objectives were to determine the proportion of feral swine that used the bait station site, and if baiting of feral swine altered areas of utilization, distances from location centroids to treatment location (control or bait station), and movement rates by survivors during culling activities. We hypothesized that the bait station would increase the sedentary nature of feral swine, thus reducing the potential for dispersal and hence disease dispersal. Our experiment was conducted between February and May 2011 on the Rob and Bessie Welder Wildlife Foundation (WWF) in San Patricio County, Texas. We trapped 83 feral swine and placed GPS collars on 21 animals. We established and maintained a centralized bait station on one side of the WWF from 13 March to 27 April. We conducted population-wide culling activities, including trapping, controlled shooting, drive shooting, and aerial gunning, from 3 to 27 April and removed 143 feral swine (4.6feral swine/km(2)). Areas of utilization did not differ between treatments (control or bait station). However, we found location centroids of bait station site feral swine to be closer to the treatment location than those of control site animals and daily movement rates of bait station site feral swine to be 39% greater than movement rates of control site animals. Based on our observation that only 62% of feral swine trapped in proximity to the bait station used it, we cannot recommend baiting as an alternative to fences for containing animals during culling activities. However, there is value in using bait stations to describe patterns of feral swine movements, facilitate observation, and improve efficacy when conducting removals.     

Efficacy of the Boar-Operated-System to deliver baits to feral swine

Feral swine (Sus scrofa) pose a significant disease threat to livestock and humans. Emerging technologies to reduce feral swine disease transmission risks include fertility control, vaccination, and toxicants. However, for these technologies to be appropriate for field application, a feral swine-specific oral delivery system is needed. We used two field trials to generate information related to appropriate field application of the Boar-Operated-System (BOS?), an oral delivery system designed to provide bait access only to feral swine. Our objectives were to determine whether pre-baiting BOS? units increased bait removal and to evaluate the proportion of feral swine and non-target animals that ingest baits designed to deliver pharmaceuticals through the BOS?. During both trials we used baits housed within 10 BOS? units. We monitored wildlife visitation, bait removal, and ingestion using motion sensing digital photography and baits containing the bait marker tetracycline hydrochloride (TH). During trial 1 we found three of five pre-baited BOS? units were used by feral swine only. Additionally, we found the five BOS? units that were not pre-baited were not used by feral swine or non-target wildlife. During trial 2 we determined bait removal from the BOS? to be reduced by only 10% for feral swine when activated, whereas bait removal from the BOS? by all other wildlife was reduced by 100% when activated. We captured 81 feral swine and 23 raccoons and found 90% and 13% to have TH-marked teeth, respectively. With minor modifications, the BOS? should be considered a valuable tool to be used in feral swine disease management in conjunction with existing technologies.     

Identification of Brucella spp. in feral swine (Sus scrofa) at abattoirs in Texas,USA

Various tissues, nasal swabs, urine and blood samples were collected from 376 feral swine at two federally inspected abattoirs in Texas during six separate sampling periods in 2015. Samples were tested for Brucella spp. by culture and serology. Brucella spp. were cultured from 13.0% of feral swine, and antibodies were detected in 9.8%. Only 32.7% of culture‐positive feral swine were also antibody positive, and 43.2% of antibody‐positive feral swine were culture positive. Approximately, the same number of males (14.0%) and females (12.1%) were culture positive, and slightly more males (10.5%) than females (8.7%) were antibody positive. Our results indicate that serology likely underestimates the prevalence of feral swine infected, and that those who come in contact with feral swine should be aware of the symptoms of infection with Brucella spp. to ensure prompt treatment.     

Variation of Aujeszky's disease viruses in wild swine in USA

In the United States of America, Aujeszky's disease (pseudorabies) has been eradicated from all domestic swine. Some re-emergence of infection occurred as vaccine use diminished. Sporadic outbreaks have also occurred because of the reservoir of infection in feral swine that have spread across the southern two-thirds of the country and Hawaii. In order to be able to understand the origins of re-emerging virus, sequence analysis of variable genes in pseudorabies virus (PRV) has been used to differentiate strains. Most PRV from feral swine can be distinguished from virus circulating in domestic pigs during the national epizootic. However, several feral swine isolates of PRV from south central states are closely related or identical in sequence to strains from domestic pigs. Extensive study by PCR for the presence of virus in the oral cavity of feral pigs disclosed that the viral DNA is distributed widely in tonsils salivary glands, taste buds and even mucosa in the vicinity of tusks. Clearly the virus in feral swine has multiple mechanisms of transmission to insure persistent infection and the threat of re-emergence in domestic swine continues.     

Preferential sexual transmission of pseudorabies virus in feral swine populations may not account for observed seroprevalence in the USA

This paper compares the behavior of two competing models for the transmission of pseudorabies virus in feral swine in the USA. In first model, horizontal (non-sexual) density dependent transmission is the only transmission modality. In the second model, the only transmission modality is sexual transmission between mature males and females. The comparison of model behavior was carried out to test the hypothesis that preferential sexual transmission of PRV in feral swine can account for the seroprevalence observed in the field. The observed range of seroprevalence of PRV in mature feral swine in the USA is consistent with a preferential sexual transmission only if the feral swine mating system is a random mating system or a polygynous system in which there is a relatively large rate of acquisition of new mates. The observed range of seroprevalence of PRV in mature feral swine in the USA is not consistent with a preferential sexual transmission if there is mate guarding. This is important because the National Pseudorabies Surveillance Plan deems monitoring the risk of PRV introduction from feral swine to be a "minor objective" both in terms of the scope of the plan and with respect to the resources allocated. The rationale for this statement was derived from experimental studies, which suggested that the PRV indigenous to feral swine in the USA is preferentially sexually transmitted.     

Economic analysis of an epizootic of pseudorabies and subsequent production following the institution of a vaccination program in a Pennsylvania swine herd

The economic impact of pseudorabies was examined in a commercial swine herd. At the onset of clinical signs, a modified-live virus vaccine was administered to the sow herd and repeated at 3-month intervals. According to production data from the 320-sow farrow-to-feeder unit, preweaning mortality increased twofold, and subsequently, the number of pigs weaned per litter decreased by 19% (P less than 0.005) during the 5-week epizootic. Also, the number of pigs born alive decreased by 6% during the epizootic (P less than 0.05). No significant differences in production were observed between the 6-month periods before and after the epizootic. Actual cash flow analysis for the farm under isomarket conditions revealed a decreased net return of $2.40/inventoried sow/week, which was attributed to the disease during the epizootic, and a $0.46 decrease in net return/inventoried sow/week in the postepizootic period. Most seropositive herds have clinical signs less severe than those described in this herd, and the cost of eradication of the virus from a swine herd can be in excess of $200/inventoried sow. Thus, we believe that sufficient financial incentives are not available to all swine producers to ensure their enthusiastic cooperation in the effort to eradicate pseudorabies from the US swine population.     

Economic impacts of reduced pork production associated with the diagnosis of Actinobacillus pleuropneumoniae on grower/finisher swine operations in the United States

An examination of the economic impacts of the diagnosis of Actinobacillus pleuropneumoniae on grower/finisher swine operations indicated that reduced pork production, associated with the diagnosis of A. pleuropneumoniae on the operation, diminished consumer surplus by $53 ± 52 million, and resulted in a total loss of $32 ± 30 million to the US economy in 1995. Most of the economic surplus lost by consumers was transferred to producers, whose economic surplus increased by $21 ± 25 million (which was not significantly different from zero). Uncertainty analysis showed that an estimate of the decline in production associated with the diagnosis of A. pleuropneumoniae accounted for most of the uncertainty of the change in consumer surplus and of the total loss to the economy. The estimate of the price elasticity of demand for pork also contributed towards a lot of the uncertainty in the estimated change in producer surplus.     

Isolation of Campylobacter from feral swine (Sus scrofa) on the ranch associated with the 2006 Escherichia coli O157:H7 spinach outbreak investigation in California

We report the isolation of Campylobacter species from the same population of feral swine that was investigated in San Benito County, California, during the 2006 spinach-related Escherichia coli O157:H7 outbreak. This is the first survey of Campylobacter in a free-ranging feral swine population in the United States. Campylobacter species were cultured from buccal and rectal-anal swabs, colonic faeces and tonsils using a combination of selective enrichment and antibiotic-free membrane filtration methods. Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF-MS, Bruker Daltonics, Inc., Billerica, MA, USA) was used to identify species followed by confirmatory multiplex PCR or 16S rRNA sequencing. Genetic relatedness of Campylobacter jejuni and Campylobacter coli strains was determined by multilocus sequence typing (MLST) and porA allele sequencing. Altogether, 12 (40%) of 30 feral swine gastrointestinal and oral cavity specimens were positive, and six species were isolated: Campylobacter coli, Campylobacter fetus, Campylobacter hyointestinalsis, Campylobacter jejuni, Campylobacter lanienae and Campylobacter sputorum. Campylobacter jejuni subtypes were closely related to MLST sequence type 21 (ST-21) and had identical porA sequences. Campylobacter coli subtypes were unrelated to isolates in the pubMLST/porA database. This feral swine population lived in close association with a 'grassfed' beef cattle herd adjacent to spinach and other leafy green row crop fields. The findings underscore the importance of protecting raw vegetable crops from faecal contamination by wild or feral animals. The study also illustrates a potential risk of Campylobacter exposure for hunters during handling and processing of wild swine meat.     

Diagnostic characterization of a feral swine herd enzootically infected with Brucella.

Eighty feral swine were trapped from a herd that had been documented to be seropositive for Brucella and which had been used for Brucella abortus RB51 vaccine trials on a 7,100-hectare tract of land in South Carolina. The animals were euthanized and complete necropsies were performed. Samples were taken for histopathology, Brucella culture, and Brucella serology. Brucella was cultured from 62 (77.5%) animals. Brucella suis was isolated from 55 animals (68.8%), and all isolates were biovar 1. Brucella abortus was isolated from 28 animals (35.0%), and isolates included field strain biovar 1 (21 animals; 26.3%), vaccine strain Brucella abortus S19 (8 animals, 10.0%), and vaccine strain Brucella abortus RB51 (6 animals, 7.5%). Males were significantly more likely to be culture positive than females (92.9% vs. 60.6%). Thirty-nine animals (48.8%) were seropositive. Males also had a significantly higher seropositivity rate than females (61.9% vs. 34.2%). The relative sensitivity rates were significantly higher for the standard tube test (44.6%) and fluorescence polarization assay (42.6%) than the card agglutination test (13.1%). Lesions consistent with Brucella infection were commonly found in the animals surveyed and included inflammatory lesions of the lymph nodes, liver, kidney, and male reproductive organs, which ranged from lymphoplasmacytic to pyogranulomatous with necrosis. This is the first report of an apparent enzootic Brucella abortus infection in a feral swine herd suggesting that feral swine may serve as a reservoir of infection for Brucella abortus as well as Brucella suis for domestic livestock.     

A congenital persistent swine fever infection. I. Clinical and virological observations

A congenital swine fever infection is described. The infection is characterized by persistent viraemia, continuous virus excretion and late onset of disease, with death occurring 2–11 months after birth.A “carrier sow” from a field outbreak gave birth to one dead, one slightly abnormal and nine normal piglets, six of which were allowed to live. Disease symptoms were not observed before the age of 9–28 weeks (average 20 weeks) and the average survival time was over 6 months. Virus titres in blood plasma fluctuated between 10^5?0 and 10^6?9 plaque forming units/ml and virus was excreted throughout the lives of the pigs. Leucocyte counts showed normal to subnormal values, falling below 10 000/mm³ at about the onset of illness. Lesions characteristics of swine fever were not observed, but severe atrophy of the thymus was seen in all animals. Cryostat sections revealed the presence of viral antigen in lymphoidal, reticulo-endothelial and epithelial tissues. The difference between this persistent congenital infection and the chronic swine fever described by other authors, and the importance of “healthy” virus carriers for the epizootiology of the disease are discussed.     

Electron microscopy of radiating clubs in tonsillar crypts of swine

Tonsils of 25 adult swine with inflamed crypts were screened for the presence of radiating clubs, and five were selected for electron microscopic study of pathogenesis of clubs. Radiating clubs in crypts were surrounded by an exudate which principally contained neutrophils. Clubs were present on the outer surface of bacterial microcolonies; they also were present on the outer surface of plant particles wedged in crypts or on the cell walls of these particles near bacterial microcolonies. The study demonstrated development of clubs from an amorphous material derived from bacterial and leukocytic cells and also from precipitated proteins. The amorphous material was shaped into clubs by a protracted phagocytic activity of numerous neutrophilic leukocytes. The lesions with radiating clubs within crypts were not surrounded by granulomatous inflammation due to the intact epithelial lining of crypts, and therefore they differ from the granulomas having clubs around microbial colonies. They could, however, serve as models of pathogenesis of radiating clubs in the purulent core of specific granulomas with radiating clubs.     

Commercial moose meat production in SwedenLa production commerciale de viande d'élan en SuèdeGewerbliche produktion von elchfleisch in Sweden

Moose meat is produced commercially in Sweden by the hunting of wild, free-range animals. Extensive forests, continual rejuvenation of the browse resource, a moderate climate, and the relative absence of natural causes of mortality contribute to the maintenance of a large and productive moose population. Hunting rights are owned by the landowner and both hunting rights and harvested animals are marketed. Exported moose meat is federally inspected and carcasses are processed in federally approved abattoirs. One commercial operation studied in detail in 1979 had fewer than 1% of its processed carcasses condemned. All traumatized tissue was removed from carcasses during processing. Weight loss associated with carcass cooling plus removal of traumatized tissue averaged 10% of fresh carcass weight. The average retail value of boneless moose meat sold on the Swedish market in 1979 was approximately U.S. $10.00 per kg. The annual moose harvest in 1981 totalled 152 000 animals with an estimated total carcass yield of 19.7 million kg. The present level of commercial production is insufficient to meet the demands of foreign or domestic markets. Not all harvested moose are marketed, however, and the commercial sale of moose meat is increasing, a trend that will probably continue if the recent levels of moose harvest are maintained.     

Economic Impacts of the U.S. Gulf of Mexico Recreational For-Hire Fishing Industry

IMPLAN Version 3.0 was used with a 2008 IMPLAN data package to estimate the economic impacts of the recreational for-hire (RFH) fishing industry in the U.S. Gulf of Mexico (GOM). Initial, direct, indirect, and induced impacts were estimated. Impacts were estimated for head, charter, and guide boat operations for Texas, Louisiana, Mississippi, and Alabama (combined), and West Florida as individual state models, while introducing multiregional spillover effects that account for regional linkages between states. These updated data are necessary to meet national standards set forth by the Magnuson-Stevens Act, such that social and economic ramifications of proposed federal fishing regulations in the GOM can be made part of the overall decision- and policymaking process.     

鸡和猪分泌型免疫球蛋白A结构蛋白的比较

通过SephadexG 2 0 0凝胶过滤和DEAE纤维素柱 ,分别从胆汁和初乳中提纯鸡和猪的分泌型免疫球蛋白A (SIgA)。SDS PAGE结果显示 ,鸡SIgA的轻链分子量约为 2 6 0 0 0～ 2 80 0 0 ,与鸡IgG的轻链分子量相似 ,而重链分子量约为 670 0 0～ 70 0 0 0 ,比鸡IgG的分子量要大。猪的SIgA与猪IgG的轻链和重链的分子量均相同。轻链的分子量约为 2 6 0 0 0～ 2 80 0 0 ;重链的分子量约为 53 0 0 0～ 570 0 0。猪SIgA中J链的分子量为 1 6 0 0 0～ 1 70 0 0。本实验证明鸡SIgA轻链的分子量与猪的SIgA的轻链相似 ,而鸡SIgA重链的分子量则高于猪的SIgA的重链     

Morphine-isoflurane interaction in dogs, swine and Rhesus monkeys

In monkeys, dogs and swine (six each) we tested the reduction of the isoflurane MAC (minimal alveolar concentration) produced by 2 mg-kg^-1 morphine intravenously (i-v.) and the concurrent effect on Pco₂ with spontaneous ventilation. MAC fell to a minimum of 55% of control at 53 min in monkeys, 50% at 38 min in dogs and 13% at 33 min in swine. Paco₂ rose at constant MAC with morphine to 55–60 mmHg, but did not fall over the next several hours despite the decline of plasma morphine concentration, and the resulting needed rise in isoflurane concentration to keep the anaesthesia depth at 1 MAC. After isoflurane concentration had returned to pre-morphine control levels, naloxone immediately reduced Paco₂ to or below control level. Morphine pharmacokinetics in the three species studied conformed to a two-compartment model.     

Injection site surveys in Canadian yearling cattle and cull cows and bulls: fall 1997.

In subprimals from yearling cattle, lesions were found in 16% top butts, 23% blades, 6% eye of rounds, 3% inside rounds, and 8% outside rounds, costing $ 9.58/head processed ($21 million annually). In cull cows and bulls, lesions were found in 35% outside rounds, costing $6.34/head processed ($4.1 million annually).     

Exposure of feral swine (Sus scrofa) in the United States to selected pathogens

Feral swine (Sus scrofa) are widely distributed in the United States. In 2011 and 2012, serum samples and tonsils were recovered from 162 and 37 feral swine, respectively, in the US to evaluate exposure to important swine endemic pathogens. Antibodies against porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) were found in 2.5% and 25.3% of tested sera, respectively. Positive serological reactions against Mycoplasma hyopneumoniae and Actinobacillus pleuropneumoniae have been detected in 19.7% and 69.7% of animals. More than 15% of animals presented antibodies against these 2 pathogens simultaneously. Most animals were also seropositive for Lawsonia intracellularis. Feral swine can also be involved in transmission of zoonotic agents. Almost 50% of animals possessed antibodies against Salmonella. In addition, 94.4% of animals were carriers of Streptococcus suis in their tonsils. In conclusion, feral swine may be considered as a potential reservoir for different endemic diseases in domestic pigs, as well as for important zoonotic agents.