Minnesota Veterinary Diagnostic Laboratory Research Articles

Assessment of porcine reproductive and respiratory syndrome virus (PRRSV) farm surface contamination through environmental sampling

BackgroundDuring the fall of 2020, the porcine reproductive and respiratory syndrome virus (PRRSV) L1C.5 variant emerged and rapidly spread throughout southern Minnesota generating questions regarding possible transmission routes. This study aimed to investigate whether PRRSV could be detected on surfaces inside and outside pig barns housing L1C.5 variant PRRSV-positive pigs to illustrate the potential for indirect transmission of PRRSV. Seven Midwestern U.S. PPRS-positive breeding or growing pig farms and one PRRS-negative farm were conveniently selected. Internal and external barn surfaces were wiped using a PBS moistened cloth and the resulting liquid was submitted to the University of Minnesota Veterinary Diagnostic Laboratory for PRRSV RT-PCR testing and virus isolation.ResultsAll (n = 26) samples from PRRSV-negative farm tested negative. Nineteen (13%) out of 143 samples from positive farms yielded positive RT-PCR results. Positive samples originated primarily from exhaust fan cones and doorknobs, followed by anteroom floor and mortality carts/sleds. Virus isolation attempted on two samples did not yield positive results.ConclusionsPRRSV contamination can occur on surfaces inside and outside pig barns that are in frequent contact with farm personnel. Although virus isolation attempts were negative, our results illustrate the potential for PRRSV to be transmitted indirectly through contaminated materials or farm personnel. The study supports the implementation of biosecurity practices by farm personnel to prevent the introduction of PRRSV into farms and the prevention of PRRSV transmission between farms.

Embolic necrosuppurative pneumonia in domestic cats induced by a novel Neisseria species.

Three cats, aged 2 to 11 years, presented to the University of Minnesota Veterinary Diagnostic Laboratory over a 3-year period following euthanasia or death due to respiratory distress. Thoracic radiographs revealed nodular, soft tissue opacities throughout the lung fields in all cases. On postmortem examination, approximately 60% to 80% of the lung parenchyma were expanded by multifocal to coalescing, well-demarcated, beige, semi-firm nodules. Histologically, large numbers of neutrophils, fewer macrophages, fibrin, and cellular and karyorrhectic debris effaced the pulmonary parenchyma. The inflammatory foci contained aggregates of gram-negative cocci. 16s rRNA Sanger sequencing and whole-genome sequencing identified the bacteria isolated from the lung of all cats under aerobic conditions as a novel Neisseria spp. Based on whole-genome sequence analysis, all 3 sequences shared 92.71% and 92.67% average nucleotide identity with closely related Neisseria animaloris NZ LR134440T and Neisseria animaloris GCA 002108605T, respectively. The in silico DNA-DNA hybridization identity compared to our isolates was 46.6% and 33.8% with strain DSM Neisseria zoodegmatis 21642 and strain DSM 21643, respectively. All 3 sequences have less than 95% average nucleotide identity and less than 70% DNA-DNA hybridization identity, suggesting that the 3 isolates are a novel species of the genus Neisseria. Infection with Neisseria spp. induces an embolic pneumonia in cats that radiographically and pathologically resembles a metastatic neoplastic process and should be considered among the etiologic differential diagnoses in cases of infectious pulmonary disease with a disseminated, nodular lung pattern.

Epidemiological Investigation of Meningeal Worm-Induced Mortalities in Small Ruminants and Camelids Over a 19 Year Period.

Meningeal worm, or Parelaphostrongylus tenuis (P. tenuis) is a nematode parasite that can invade the nervous system of small ruminant and camelid species such as alpaca, llama, goats and sheep. Limited reports exist on the epidemiology of disease caused by the nematode in susceptible livestock. We examined archived necropsy reports from small ruminant and camelid mortalities that were submitted, post mortem, to the University of Minnesota Veterinary Diagnostic Laboratory (MNVDL) during 2001–2019 for gross necropsy, histopathology, and pathogen screening. We estimated P. tenuis-induced mortality over time and developed temporal models to better understand patterns and drivers of P. tenuis-induced mortalities in these animals. During the period under examination, 5,617 goats, sheep, llamas and alpacas were necropsied, revealing an overall P. tenuis-induced mortality rate of 1.14% in the necropsy submission pool for these species. P. tenuis-induced mortality rates were highest in llamas (9.91%) and alpacas (5.33%) compared to sheep and goats (<1%), with rates in llamas and alpacas significantly higher than in sheep and goats. P. tenuis-induced mortalities exhibited one seasonal peak, around October to December. P. tenuis-induced mortality rates varied greatly between years, and have significantly increased over time. We also observed a positive correlation between summer temperature (range 20.4–22.4°C) and P. tenuis-induced mortality rates (range 0–3.9%), but not precipitation. This study demonstrates seasonal patterns and differences in mortality between alpacas, goats, llamas and sheep and helps us to better understand the epidemiology of P. tenuis mortality.

Detection and molecular characterization of astro and bocaviruses in dogs in Minnesota

Canine astrovirus (CAstV) and canine bocavirus (CBoV) are involved in cases of mild, and sometimes severe, gastroenteritis in dogs. Fecal samples from two dead dogs with gastroenteritis were received at the University of Minnesota Veterinary Diagnostic Laboratory to determine the cause of death. Small round viruses of 20–35 nm diameter were observed by negative contrast electron microscopy. The samples were subjected to Illumina MiSeq sequencing. Both samples were strongly positive for CAstV; all viral reads were related to CAstV. In addition, sample number 1 had a few reads of CBoV. Two complete sequences of CAstV were identified (6625 and 6627 nt in length) with 95% nt identity. RT-PCR and PCR were used to confirm CAstV and CBoV infections in successive samples of canine gastroenteritis. Sanger sequencing was done on nucleic acids from positive samples. Of a total of ten samples, CAstV and CBoV infections were confirmed in six and eight animals, respectively. Four animals had mixed infection with both viruses. All sequences of ORF1b gene of CAstVs showed closest clusters in phylogenetic tree with 96–100% nucleotide and amino acids identity. On the other hand, identity between VP2 gene of different CBoV strains in this study ranged from 93%− 100%. All strains were located close to each other except the divergent MT078234 strain, which was arranged in a separate branch and was closer to reference strain JN648103/USA/2010. This study highlights the importance of electron microscopy and next generation sequencing for early detection and characterization of viruses associated with dog gastroenteritis.

Enteric Viruses Associated with Mid-growth Turkey Enteritis.

Since August 2014, the University of Minnesota Veterinary Diagnostic Laboratory has received cases of turkey enteritis that are clinically different from previously described cases of poult enteritis syndrome and light turkey syndrome. The birds develop dark green and extremely foul-smelling diarrhea starting at 8-10 wk of age, which may last up to 15-16 wk of age. The affected turkey flocks show poor uniformity, and feed conversion and market weights are reduced. Multiple-age farms are affected more often than the single-age farms. Morbidity varies from flock to flock and in some cases reaches 100%. At necropsy, undigested feed with increased mucus is observed in the intestines along with prominent mucosal congestion and/or hemorrhage. Microscopically, lymphocytic infiltrates expand the villi in duodenum and jejunum to form lymphoid follicles, which are often accompanied by heterophils. Next generation sequencing (Illumina Miseq) on a pool of feces from affected birds identified genetic sequences of viruses belonging to Astroviridae, Reoviridae, Picornaviridae, Picobirnaviridae, and Adenoviridae. On testing pools of fecal samples from apparently healthy (16 pools) and affected birds (30 pools), there was a higher viral load in the feces of affected birds. Picobirnavirus was detected only in the affected birds; 20 of 30 pools (66.7%) were positive. These results indicate that a high viral load of turkey picobirnavirus alone, or in association with novel picornaviruses, may be a cause of this new type of turkey enteritis.

Prevalence and trend analysis of antimicrobial resistance in clinical Escherichia coli isolates collected from diseased pigs in the USA between 2006 and 2016.

Antimicrobial resistance (AMR) is an emerging threat to both human and animal health. Antimicrobial use and resistance in food animal production, including swine, has received increased scrutiny as a source of resistant foodborne pathogens. Continuous surveillance of AMR in bacterial isolates of swine origin can guide in conservation of antimicrobials used in both human and swine medicine. The objective of this study was to evaluate the prevalence and trends of the phenotypic AMR in Escherichia coli of swine origin isolated from clinical samples at the Minnesota Veterinary Diagnostic laboratory between 2006 and 2016. The prevalence of resistance to ampicillin, tetracyclines and sulphadimethoxine remained greater than 50% throughout the period. There was a drastic change in enrofloxacin resistance, increasing from less than 1% to more than 20% between 2006 and 2016 (annual relative increase of 57% between 2006 and 2013 and 16% between 2013 and 2016). The prevalence of resistance to other antimicrobials remained constant (ceftiofur, oxytetracycline and chlortetracycline) or changed significantly (annual relative changes of less than 10%) for at least some time-period between 2006 and 2016 (ampicillin, florfenicol, gentamicin, neomycin, sulphadimethoxine, trimethoprim-sulphamethoxazole and spectinomycin). Rarefaction analysis revealed an increase in the number of unique combinations of AMRs per year. Network analysis was performed by estimating and plotting partial correlations between minimum inhibitory concentrations (MICs) of various antimicrobials. An increase in strength of these networks was observed, particularly in networks created after 2010, which can be indicative of increased multiple AMR in these isolates. These results provide valuable insight into the trends in AMR in E. coli of swine origin in the USA and act as supplementary information to the existing active AMR surveillance systems.

Prevalence and time trend analysis of antimicrobial resistance in respiratory bacterial pathogens collected from diseased pigs in USA between 2006–2016

Swine respiratory disease complex (SRDC) causes massive economic losses to the swine industry and is a major animal welfare concern. Antimicrobials are mainstay in treatment and control of SRDC. However, there is a lack of data on the prevalence and trends in resistance to antimicrobials in bacterial pathogens associated with SRDC. The objective of this study was to estimate the prevalence and changes in resistance to 13 antimicrobials in swine bacterial pathogens (Streptococcus suis, Pasteurella multocida, Actinobacillus suis and Haemophilus parasuis) in the U.S.A using data collected at University of Minnesota Veterinary Diagnostic Laboratory between 2006 and 2016. For antimicrobials for which breakpoints were available, prevalence of resistance remained below 10% except for tetracycline in S. suis and P. multocida isolates, and these prevalence estimates remained consistently low over the years despite statistical significance (p < .05) in trend analysis. For antimicrobial-bacterial combinations without available breakpoints, the odds of isolates being resistant increased by >10% annually for 7 and 1 antimicrobials in H. parasuis and S. suis isolates respectively, and decreased >10% annually for 4 and 1 antimicrobials in A. suis and H. parasuis isolates, respectively, according to the ordinal regression models. Clinical implications of changes in AMR for A. suis and H. parasuis should be interpreted cautiously due to the lack of interpretive criteria and challenges in antimicrobial susceptibility tests in the case of H. parasuis. Future studies should focus on surveillance of antimicrobial resistance and establishment of standardized susceptibility testing methodologies and interpretive criteria for these animal pathogens of critical importance.

Retrospective Analysis of Turkey Arthritis Reovirus Diagnostic Submissions in Minnesota.

Turkey arthritis reovirus (TARV) causes tenosynovitis in turkeys, resulting in decreased profits for producers due to the increase in morbidity, mortality, and feed conversion ratio. There is limited information on TARV epidemiology, including the dynamics of diagnostic submissions to veterinary diagnostic laboratories. In this study, we retrospectively analyzed 719 cases of lameness in turkeys submitted to the Minnesota Veterinary Diagnostic Laboratory from March 2010 to May 2018. Almost all submissions were tendon pools, which were tested by virus isolation and/or real-time reverse transcription-polymerase chain reaction. Most of the submissions were from Minnesota. We found 52% of the submitted cases to be positive for TARV. The TARV-positive submissions increased considerably in the last few years. There was no statistical evidence that TARV diagnostic submissions were seasonal, although positive submissions were higher in January, April, July, and December. TARV-positive submissions also increased as flocks aged. In summary, we found that TARV submissions have increased in the last few years, have varied over time, and are correlated with age of the bird. This information is important guidance for conducting more studies to understand TARV infection dynamics.

Seroprevalence of Brucella canis antibodies in dogs entering a Minnesota humane society, Minnesota, 2016–2017

BackgroundCanine brucellosis, caused by the bacterium Brucella canis, is a zoonotic and largely reproductive disease of dogs. The disease is a recognized problem in canine breeding populations, and the risk to individuals assisting with birthing is well described. Prior to 2015, all cases of canine brucellosis reported to the Minnesota Board of Animal Health were in dogs used for breeding. In 2015, canine brucellosis was identified in eight Minnesota rescue dogs, all originating from specific geographic areas in South Dakota. Our objective was to measure the seroprevalence of B. canis in stray and previously owned dogs entering a large Minnesota animal rescue organization to determine if our observations represented a localized or generalized disease issue among rescue dogs. MethodsA stratified random sample of stray and previously owned dogs entering the largest Minnesota animal rescue organization between November 1, 2016 and November 7, 2017, was tested for B. canis antibodies by the 2-Mercaptoethanol Rapid Slide Agglutination Test (2ME-RSAT) (Zoetis d-TEC® CB kit). Sample sizes for each strata were calculated using previously published seroprevalence estimates. Blood from selected dogs was collected, serum harvested, and transported to the Minnesota Veterinary Diagnostic Laboratory for testing. Positive samples in the 2ME-RSAT were shipped to Cornell University for confirmation by Agarose Gel Immunodiffusion (AGID) testing. Demographics, state and setting of origin, and health status were collected on study-dogs. ResultsOf the 10,654 dogs accepted by AHS during the study period, 943 (8.9%) were selected for testing. Most study dogs arrived from Oklahoma (28%), Alabama (18%), and Minnesota (12%). The median age of study dogs was 1.5 years; 303 (32%) were intact males and 294 (31%) were intact females. Most study dogs were strays (n = 716, 76%). Of the total, 22 (3.1%) stray and eight (3.5%) owner-surrendered dogs were presumptively positive by RSAT; one (0.11%) of the stray dogs was positive by 2ME-RSAT and confirmed by AGID. The positive dog was a healthy-appearing 1 year-old neutered male beagle from Texas. ConclusionsThe seroprevalence of canine brucellosis in dogs entering Minnesota for adoption from multiple states was low. Never-the-less, care must to be taken to consider all potential risks and outcomes of interstate and international dog trade, including the spread of infectious diseases such as canine brucellosis.

Longitudinal study of Senecavirus a shedding in sows and piglets on a single United States farm during an outbreak of vesicular disease

BackgroundThe study highlights the shedding pattern of Senecavirus A (SVA) during an outbreak of vesicular disease in a sow farm from the South-central Minnesota, USA. In this study, 34 individual, mixed parity sows with clinical signs of vesicular lesions and 30 individual piglets from 15 individual litters from sows with vesicular lesions were conveniently selected for individual, longitudinal sampling. Serum, tonsil, rectal, and vesicular swabs were collected on day1 post outbreak, and then again at 1, 2, 3, 4, 6, and 9 weeks post outbreak. Samples were tested at the University of Minnesota Veterinary Diagnostic Laboratory for SVA via Real Time Polymerase Chain Reaction (RT-PCR)ResultsIn sows, vesicular lesions had the highest concentration of SVA, but had the shortest duration of detection lasting only 2 weeks. Viremia was detected for 1 week post outbreak, and quickly declined thereafter. SVA was detected at approximately the same frequency for both tonsil and rectal swabs with the highest percentage of SVA positive samples detected in the first 6 weeks post outbreak. In suckling piglets, viremia quickly declined 1 week post outbreak and was prevalent in low levels during the first week after weaning (4 weeks post outbreak) and was also detected in piglets that were co-mingled from a SVA negative sow farm. Similar to sows, SVA detection on rectal and tonsil swabs in piglets lasted approximately 6 weeks post outbreak.ConclusionThe study illustrates the variation of SVA shedding patterns in different sample types over a 9 week period in sows and piglets, and suggests the potential for viral spread between piglets at weaning.

Outbreak of highly pathogenic avian influenza in Minnesota in 2015.

The incursion of highly pathogenic avian influenza (HPAI) into the United States during 2014 resulted in an unprecedented foreign animal disease (FAD) event; 232 outbreaks were reported from 21 states. The disease affected 49.6 million birds and resulted in economic losses of $950 million. Minnesota is the largest turkey-producing state, accounting for 18% of U.S. turkey production. Areas with concentrated numbers of turkeys in Minnesota were the epicenter of the outbreak. The first case was presumptively diagnosed in the last week of February 2015 at the Minnesota Veterinary Diagnostic Laboratory (MVDL) and confirmed as HPAI H5N2 at the National Veterinary Services Laboratories on March 4, 2015. A total of 110 farms were affected in Minnesota, and the MVDL tested >17,000 samples from March to July 2015. Normal service was maintained to other clients of the laboratory during this major FAD event, but challenges were encountered with communications, staff burnout and fatigue, training requirements of volunteer technical staff, test kit validation, and management of specific pathogen-free egg requirements.

Prevalence of parvovirus in Minnesota turkeys

Poult enteritis syndrome (PES) is characterized by enteritis and decreased body weight gain in growing turkey poults between one d and 7 wk of age. Another syndrome called light turkey syndrome (LTS) causes a decrease in body weight of adult tom turkeys in Minnesota leading to huge economic losses. Reovirus, rotavirus, and astrovirus have been found in LTS and PES flocks in Minnesota. We tested 80 fecal pools collected from four LTS flocks and 35 fecal pools from non-LTS flocks for the presence of parvovirus. In addition, 116 fecal and meconium samples from turkeys submitted to the Minnesota Veterinary Diagnostic Laboratory (MVDL) also were tested. The samples were tested by PCR using primers for the non-structural 1 (NS1) gene of parvovirus. Of the 80 samples from LTS flocks, 41 were positive for parvovirus while 20 of 35 samples from non-LTS flocks were positive. The prevalence of parvovirus in fecal samples submitted to MVDL was relatively low; only five of the 116 pools were positive. The partial NS1 gene sequences from LTS and non-LTS samples showed 98 to 100% nt identity except for one divergent turkey parvovirus (TuPV) strain that revealed 90% identity and clustered with chicken-like parvoviruses. The presence of this divergent strain suggests circulation of a recombinant strain of TuPV in Minnesota turkeys. Our results indicate that TuPVs are circulating in both LTS and non-LTS flocks of turkeys in Minnesota, and further experimental studies are indicated to study the role of TuPV in LTS.

Serotypes and Antimicrobial Resistance in Salmonella enterica Recovered from Clinical Samples from Cattle and Swine in Minnesota, 2006 to 2015.

Salmonellosis remains one of the leading causes of foodborne disease worldwide despite preventive efforts at various stages of the food production chain. The emergence of multi-drug resistant (MDR) non-typhoidal Salmonella enterica represents an additional challenge for public health authorities. Food animals are considered a major reservoir and potential source of foodborne salmonellosis; thus, monitoring of Salmonella strains in livestock may help to detect emergence of new serotypes/MDR phenotypes and to gain a better understanding of Salmonella epidemiology. For this reason, we analyzed trends over a nine-year period in serotypes, and antimicrobial resistance, of Salmonella isolates recovered at the Minnesota Veterinary Diagnostic Laboratory (MVDL) from swine (n = 2,537) and cattle (n = 1,028) samples. Prevalence of predominant serotypes changed over time; in swine, S. Typhimurium and S. Derby decreased and S. Agona and S. 4,5,12:i:- increased throughout the study period. In cattle, S. Dublin, S. Montevideo and S. Cerro increased and S. Muenster became less frequent. Median minimum inhibitory concentration (MIC) values and proportion of antibiotic resistant isolates were higher for those recovered from swine compared with cattle, and were particularly high for certain antibiotic-serotype combinations. The proportion of resistant swine isolates was also higher than observed in the NARMS data, probably due to the different cohort of animals represented in each dataset. Results provide insight into the dynamics of antimicrobial resistant Salmonella in livestock in Minnesota, and can help to monitor emerging trends in antimicrobial resistance.

Three-Level Mixed-Effects Logistic Regression Analysis Reveals Complex Epidemiology of Swine Rotaviruses in Diagnostic Samples from North America.

Rotaviruses (RV) are important causes of diarrhea in animals, especially in domestic animals. Of the 9 RV species, rotavirus A, B, and C (RVA, RVB, and RVC, respectively) had been established as important causes of diarrhea in pigs. The Minnesota Veterinary Diagnostic Laboratory receives swine stool samples from North America to determine the etiologic agents of disease. Between November 2009 and October 2011, 7,508 samples from pigs with diarrhea were submitted to determine if enteric pathogens, including RV, were present in the samples. All samples were tested for RVA, RVB, and RVC by real time RT-PCR. The majority of the samples (82%) were positive for RVA, RVB, and/or RVC. To better understand the risk factors associated with RV infections in swine diagnostic samples, three-level mixed-effects logistic regression models (3L-MLMs) were used to estimate associations among RV species, age, and geographical variability within the major swine production regions in North America. The conditional odds ratios (cORs) for RVA and RVB detection were lower for 1–3 day old pigs when compared to any other age group. However, the cOR of RVC detection in 1–3 day old pigs was significantly higher (p < 0.001) than pigs in the 4–20 days old and >55 day old age groups. Furthermore, pigs in the 21–55 day old age group had statistically higher cORs of RV co-detection compared to 1–3 day old pigs (p < 0.001). The 3L-MLMs indicated that RV status was more similar within states than among states or within each region. Our results indicated that 3L-MLMs are a powerful and adaptable tool to handle and analyze large-hierarchical datasets. In addition, our results indicated that, overall, swine RV epidemiology is complex, and RV species are associated with different age groups and vary by regions in North America.

Detection and molecular characterization of astroviruses in turkeys.

This study was conducted to determine the prevalence and molecular characteristics of turkey astrovirus 1 (TAstV-1) and avian nephritis virus (ANV) in turkeys with light turkey syndrome (LTS), which is characterized by lower body weight in market-age turkeys than their standard breed character. We collected pools of fecal samples from four LTS and two non-LTS turkey flocks in Minnesota at 2, 3, 5 and 8 weeks of age. Of the 80 LTS pools tested, 16 (20.0 %) and 11 (13.8 %) were positive for TAstV-1 and ANV, respectively. For non-LTS flocks, these numbers were 8 (20.0 %) and 5 (12.5 %), respectively. The maximum number of birds was positive at five weeks of age. We also tested 130 fecal samples of poult enteritis syndrome (PES) cases submitted to the Minnesota Veterinary Diagnostic Laboratory and found 19 and 11 positive for TAstV-1 and ANV, respectively. RdRp gene sequences were determined for a total of 29 TAstV-1 and 22 ANV samples. Phylogenetic analysis of the RdRp gene revealed 92-100 % and 88-100 % nucleotide sequence identity among TAstV-1 and ANV sequences, respectively. A large number of nucleotide and amino acid substitutions were observed in LTS and PES flocks than in non-LTS flocks. One of the PES sequences grouped with ANV-like sequences detected in chickens, indicating that regular screening of birds should be continued. Further, complete genome analysis should be conducted to determine whether this virus is a novel divergent strain or a recombinant of chicken and turkey ANV-like viruses. The detection of TAstV-1 and ANV in a considerable number of non-LTS cases emphasizes the need for further studies on the transmission pattern and pathogenesis of these viruses to determine their role as pathogens of turkeys.

Description of the Microsporidian Parasite, Heterosporis sutherlandae n. sp., Infecting Fish in the Great Lakes Region, USA.

Heterosporosis is an increasingly important microsporidian disease worldwide, impacting wild and farmed raised fishes in both marine and freshwater environments. A previously undescribed species (Heterosporis sp.), with widespread distribution in the Great Lakes region, was the subject of this study. Three angler-caught fish were submitted to the Minnesota Veterinary Diagnostic Laboratory from 2009–2010 with lesions caused by intracellular proliferation of parasitic spores, resulting in destruction and eventual widespread necrosis of the host skeletal muscles. Mature ovoid (5.8 x 3.5μm) spores of a microsporidian parasite, consistent with the genus Heterosporis, were observed by light and electron microscopy. Molecular identification was performed using primer walking to obtain a near-complete rRNA gene sequence (~3,600 bp). A unique species of Heterosporis was identified, demonstrating less than 96% sequence identity to other published Heterosporis sp. on the basis of partial rRNA gene sequence analysis. Heterosporis sutherlandae n. sp. (formerly Heterosporis sp.) was identified in yellow perch (Perca flavescens), northern pike (Esox lucius) and walleye (Sander vitreus) from inland lakes in Minnesota and Wisconsin. Previous research suggests this species may be even more widespread in the Great Lakes region and should be reexamined using molecular techniques to better understand the distribution of this novel species.

Necropsy findings in 62 opportunistically collected free-ranging moose (Alces alces) from Minnesota, USA (2003-13).

The Minnesota, US moose population has declined dramatically since the 1990s. All 54 carcasses of moose that died of unknown cause or were euthanized by gun shot by tribal or Department of Natural Resources personnel because of perceived signs of illness between 2003 and 2013 and eight carcasses of moose that died from vehicular accidents between 2009 and 2013 were submitted to the Minnesota Veterinary Diagnostic Laboratory and included in our study. The majority of the animals were underweight or cachectic (n = 53; 85%). Neural migration presumably by Parelaphostrongylus tenuis was a common finding (n = 28; 45%). Moderate to marked Dermacentor albipictus ("winter tick") ectoparasitism with widespread alopecia was the cause or a contributing cause of death in 14 (23%) cases in which grossly apparent anemia was associated with exhaustion of hepatic iron stores. Hepatic lesions associated with Fascioloides magna were common (n = 37; 60%) but were unlikely to be the cause of death. Environmental factors favoring winter tick survival, habitat expansion of white-tailed deer (Odocoileus virginianus), and the survival of terrestrial and aquatic snails (serving as intermediate hosts for P. tenuis and F. magna), might contribute to the seemingly severe parasitic burden in Minnesota's moose population.

Detection and molecular characterization of a reovirus in black-capped chickadees (Poecile atricapillus) from Minnesota, USA.

In 2011, the Minnesota Rehabilitation Center submitted four dead Black-capped Chickadees (Poecile atricapillus) for necropsy to the Minnesota Veterinary Diagnostic Laboratory. All four chickadees were underweight and dehydrated and their intestinal contents were watery and yellowish. No significant lesions were observed upon histopathologic examination. Viral particles of the family Reoviridae were detected after negative-contrast electron microscopic examination of intestinal contents. Analysis by reverse transcriptase PCR and sequencing confirmed the presence of a reovirus. Based on phylogenetic analysis, the chickadee reovirus had 97.1% to 98.3% and 89.4% to 97.8% nucleotide identity with turkey enteric reoviruses from apparently healthy and enteritis-affected turkey poults, respectively. The chickadee reovirus had only 56.5% and 58.5% nucleotide and 54.5% and 56.8% amino acid identity with psittacine reovirus and Tvarminne avian virus, respectively. These results indicate that the chickadee reovirus is closely related to turkey reoviruses.

ISOLATION AND CHARACTERIZATION OF A CERVIDPOXVIRUS FROM A GOITERED GAZELLE (GAZELLA SUBGUTTUROSA) FROM A ZOOLOGIC PARK IN MINNESOTA

Deerpox virus (DPV) is the sole member of the newly ratified Cervidpoxvirus genus in the subfamily Chordopoxvirinae. Presented here is the first diagnostic report of isolation of DPV from a goitered gazelle (Gazella subgutturosa). A tissue homogenate was submitted by a zoologic park to the Minnesota Veterinary Diagnostic Laboratory at the University of Minnesota for poxvirus diagnostic investigation and then referred to Plum Island Foreign Animal Disease Diagnostic Laboratory for confirmation. Poxviral infection was confirmed using electron microscopy. The virus was cultured in vero cells and subjected to further diagnoses for characterization. Polymerase chain reaction targeting the major envelope (B2L) protein and RNA polymerase of parapoxviruses, and the poly-A polymerase gene of capripoxviruses, were all negative. Degenerative pan-poxvirus primers that target the DNA polymerase (DNApol) and DNA topoisomerase (DNAtopo) genes, however, successfully amplified poxviral DNA fragments. Amplification of the DNApol and DNAtopo genes yielded fragments of 543 and 344 base pairs, respectively. DNA sequence and phylogenetic analysis of each gene fragment from the gazelle isolate showed >97% identity in BLAST searches with two DPV virus strains (W848-83 and W-1170-84) isolated from North American mule deer (Odocoileus hemionus) in 1983-1984. Neighbor-joining trees indicate that the isolate is a member of the Cervidpoxvirus genus and shows a more-distant relationship to other ruminant poxviruses, namely the Capripoxvirus genus consisting of lumpy skin disease, sheeppox, and goatpox viruses. This report documents the premiere finding of DPV, a recently characterized virus, in gazelles and demonstrates the need for broadened investigation when diagnosing poxvirus infections in ruminants.

A case of chronic wasting disease in a captive red deer (Cervus elaphus)

A 22-month-old, female red deer (Cervus elaphus) was submitted to the University of Minnesota Veterinary Diagnostic Laboratory for necropsy and chronic wasting disease (CWD) testing. The deer was found positive for the abnormal prion protein in the obex and the retropharyngeal lymph node by immunohistochemical staining. Microscopic lesions of spongiform encephalopathy and immunohistochemical staining patterns and intensity were similar to those in CWD-positive elk and experimentally infected red deer.