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Saville WJA, Reed SM, Dubey JP, Granstrom DE, Morley PS, Hinchcliff KW, Kohn CW, Wittum TE, Workman JD. Interobserver Variation in the Diagnosis of Neurologic Abnormalities in the Horse. J Vet Intern Med 2017; 31:1871-1876. [PMID: 28887894 PMCID: PMC5697190 DOI: 10.1111/jvim.14822] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 07/21/2017] [Accepted: 08/03/2017] [Indexed: 12/01/2022] Open
Abstract
BACKGROUND The diagnosis of equine protozoal myeloencephalitis (EPM) relies heavily on the clinical examination. The accurate identification of neurologic signs during a clinical examination is critical to the interpretation of laboratory results. OBJECTIVE To investigate the level of agreement between board-certified veterinary internists when performing neurologic examinations in horses. ANIMALS Ninety-seven horses admitted to the Veterinary Teaching Hospital at The Ohio State University from December 1997 to June 1998. METHODS A prospective epidemiologic research design was used. Horses enrolled in the study were examined by the internist responsible for care of the horse, and later by an internist who was not aware of the presenting complaint or other patient history. Data were analyzed by descriptive statistics, and kappa (K) statistics were calculated to assess interobserver agreement. RESULTS Ninety-seven horses were enrolled in the study. Overall, examiners, also referred to as observers, agreed that 60/97 (61.9%) were clinically abnormal, 21/97 (21.6%) were clinically normal, and the status of 16/97 (16.5%) of horses was contested. There was complete agreement among the examiners with regard to cranial nerve signs and involuntary movements. Disagreement involving severity of clinical signs occurred in 31 horses, and 25 of those horses (80.6%) were considered either normal or mildly affected by the primary observer. When examining the results of all paired clinical examinations for 11 different categories, there was wide variability in the results. When examiners rated the presence or absence of any neurologic abnormalities, lameness, or ataxia, the agreement among observers was either good or excellent for 80% of horses. When assessing truncal sway, the agreement among observers was good or excellent for 60% of the horses. When examining the horses for asymmetry of deficits, agreement was either good or excellent for 40% of the horses. Agreement among observers was excellent or good for only 20% of the horses when assessing muscle atrophy, spasticity (hypermetria), and overall assessment of the severity of neurologic abnormalities. CONCLUSIONS AND CLINICAL IMPORTANCE This study underscores the subjectivity of the neurologic examination and demonstrates a reasonable level of agreement that may be achieved when different clinicians examine the same horse.
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Affiliation(s)
- W J A Saville
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH
| | - S M Reed
- Rood and Riddle Equine Hospital, Lexington, KY
| | - J P Dubey
- United Sates Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Beltsville, MD
| | - D E Granstrom
- American Veterinary Medical Association, Schaumburg, IL
| | - P S Morley
- Colorado School of Public Health, James L. Voss Veterinary Teaching Hospital, Colorado State University, Fort Collins, CO
| | - K W Hinchcliff
- Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Vic, Australia
| | - C W Kohn
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH
| | - T E Wittum
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH
| | - J D Workman
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH
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Dryburgh EL, Marsh AE, Dubey JP, Howe DK, Reed SM, Bolten KE, Pei W, Saville WJA. Sarcocyst Development in Raccoons (Procyon lotor) Inoculated with Different Strains of Sarcocystis neurona Culture-Derived Merozoites. J Parasitol 2015; 101:462-7. [PMID: 25811893 DOI: 10.1645/15-718.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Sarcocystis neurona is considered the major etiologic agent of equine protozoal myeloencephalitis (EPM), a neurological disease in horses. Raccoon ( Procyon lotor ) is considered the most important intermediate host in the life cycle of S. neurona in the United States; S. neurona sarcocysts do mature in raccoon muscles, and raccoons also develop clinical signs simulating EPM. The focus of this study was to determine if sarcocysts would develop in raccoons experimentally inoculated with different host-derived strains of in vitro-cultivated S. neurona merozoites. Four raccoons were inoculated with strains derived from a raccoon, a sea otter, a cat, and a horse. Raccoon tissues were fed to laboratory-raised opossums ( Didelphis virginiana ), the definitive host of S. neurona . Intestinal scraping revealed sporocysts in opossums who received muscle tissue from raccoons inoculated with the raccoon-derived or the sea otter-derived isolates. These results demonstrate that sarcocysts can mature in raccoons inoculated with in vitro-derived S. neurona merozoites. In contrast, the horse and cat-derived isolates did not produce microscopically or biologically detected sarcocysts. Immunoblot analysis revealed both antigenic and antibody differences when testing the inoculated raccoons. Immunohistochemical staining indicated differences in staining between the merozoite and sarcocyst stages. The successful infections achieved in this study indicates that the life cycle can be manipulated in the laboratory without affecting subsequent stage development, thereby allowing further purification of strains and artificial maintenance of the life cycle.
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Affiliation(s)
- E L Dryburgh
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210
| | - A E Marsh
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210
| | - J P Dubey
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210
| | - D K Howe
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210
| | - S M Reed
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210
| | - K E Bolten
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210
| | - W Pei
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210
| | - W J A Saville
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210
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Tilahun G, Tiao N, Ferreira LR, Choudhary S, Oliveira S, Verma SK, Kwok OCH, Molla B, Saville WJA, Medhin G, Kassa T, Aleme H, Gebreyes WA, Su C, Dubey JP. Prevalence ofToxoplasma gondiifrom Free-Range Chickens (Gallus domesticus) from Addis Ababa, Ethiopia. J Parasitol 2013; 99:740-1. [DOI: 10.1645/12-25.1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Barsnick RJIM, Hurcombe SDA, Dembek K, Frazer ML, Slovis NM, Saville WJA, Toribio RE. Somatotropic axis resistance and ghrelin in critically ill foals. Equine Vet J 2013; 46:45-9. [PMID: 23663031 DOI: 10.1111/evj.12086] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2012] [Accepted: 03/14/2013] [Indexed: 12/27/2022]
Abstract
REASONS FOR PERFORMING STUDY Resistance to the somatotropic axis and increases in ghrelin concentrations have been documented in critically ill human patients, but limited information exists in healthy or sick foals. OBJECTIVES To investigate components of the somatotropic axis (ghrelin, growth hormone and insulin-like growth factor-1 [IGF-1]) with regard to energy metabolism (glucose and triglycerides), severity of disease and survival in critically ill equine neonates. It was hypothesised that ghrelin and growth hormone would increase and IGF-1 would decrease in proportion to severity of disease, supporting somatotropic axis resistance, which would be associated with severity of disease and mortality in sick foals. STUDY DESIGN Prospective multicentre cross-sectional study. METHODS Blood samples were collected at admission from 44 septic, 62 sick nonseptic (SNS) and 19 healthy foals, all aged <7 days. Foals with positive blood cultures or sepsis scores ≥12 were considered septic, foals with sepsis scores of 5-11 were classified as SNS. Data were analysed by nonparametric methods and multivariate logistic regression. RESULTS Septic foals had higher ghrelin, growth hormone and triglyceride and lower IGF-1 and glucose concentrations than healthy foals (P<0.01). Sick nonseptic foals had higher growth hormone and triglycerides and lower IGF-1 concentrations than healthy foals (P<0.05). Growth hormone:IGF-1 ratio was higher in septic and SNS foals than healthy foals (P<0.05). Hormone concentrations were not different between septic nonsurvivors (n = 14) and survivors (n = 30), but the growth hormone:IGF-1 ratio was lower in nonsurvivors (P = 0.043). CONCLUSIONS Somatotropic axis resistance, characterised by a high growth hormone:IGF-1 ratio, was frequent in sick foals, associated with the energy status (hypoglycaemia, hypertriglyceridaemia) and with mortality in septic foals. POTENTIAL RELEVANCE A functional somatotropic axis appears to be important for foal survival during sepsis. Somatotropic resistance is likely to contribute to severity of disease, a catabolic state and likelihood of recovery.
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Affiliation(s)
- R J I M Barsnick
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, USA
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Dubey JP, Darrington C, Tiao N, Ferreira LR, Choudhary S, Molla B, Saville WJA, Tilahun G, Kwok OCH, Gebreyes WA. Isolation of ViableToxoplasma gondiifrom Tissues and Feces of Cats from Addis Ababa, Ethiopia. J Parasitol 2013; 99:56-8. [DOI: 10.1645/ge-3229.1] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Dubey JP, Sundar N, Kwok OCH, Saville WJA. Sarcocystis neurona infection in gamma interferon gene knockout (KO) mice: comparative infectivity of sporocysts in two strains of KO mice, effect of trypsin digestion on merozoite viability, and infectivity of bradyzoites to KO mice and cell culture. Vet Parasitol 2013; 196:212-5. [PMID: 23375195 DOI: 10.1016/j.vetpar.2013.01.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 12/27/2012] [Accepted: 01/06/2013] [Indexed: 11/25/2022]
Abstract
The protozoan Sarcocystis neurona is the primary cause of Equine Protozoal Myeloencephalitis (EPM). EPM or EPM-like illness has been reported in horses, sea otters, and several other mammals. The gamma interferon gene knockout (KO) mouse is often used as a model to study biology and discovery of new therapies against S. neurona because it is difficult to induce clinical EPM in other hosts, including horses. In the present study, infectivity of three life cycle stages (merozoites, bradyzoites, sporozoites) to KO mice and cell culture was studied. Two strains of KO mice (C57-black, and BALB/c-derived, referred here as black or white) were inoculated orally graded doses of S. neurona sporocysts; 12 sporocysts were infective to both strains of mice and all infected mice died or became ill within 70 days post-inoculation. Although there was no difference in infectivity of sporocysts to the two strains of KO mice, the disease was more severe in black mice. S. neurona bradyzoites were not infectious to KO mice and cell culture. S. neurona merozoites survived 120 min incubation in 0.25% trypsin, indicating that trypsin digestion can be used to recover S. neurona from tissues of acutely infected animals.
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Affiliation(s)
- J P Dubey
- United States Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Animal Parasitic Diseases Laboratory, Building 1001, Beltsville, MD 207 05-2350, USA.
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Bolten KE, Marsh AE, Reed SM, Dubey JP, Toribio RE, Saville WJA. Sarcocystis neurona: molecular characterization of enolase domain I region and a comparison to other protozoa. Exp Parasitol 2008; 120:108-12. [PMID: 18625501 DOI: 10.1016/j.exppara.2008.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Revised: 05/12/2008] [Accepted: 05/16/2008] [Indexed: 10/22/2022]
Abstract
Sarcocystis neurona causes protozoal myeloencephalitis and has the ability to infect a wide host range in contrast to other Sarcocystis species. In the current study, five S. neurona isolates from a variety of sources, three Sarcocystis falcatula, one Sarcocystis dasypi/S. neurona-like isolate, and one Besnoitia darlingi isolate were used to compare the enolase 2 gene segment containing the domain I region to previously sequenced enolase genes from Neospora caninum, Neospora hughesi, Toxoplasma gondii, Plasmodium falciparum, and Trypanosoma cruzi; enolase 2 segment containing domain I region is highly conserved amongst these parasites of veterinary and medical importance. Immunohistochemistry results indicates reactivity of T. gondii enolase 1 and 2 antibodies to S. neurona merozoites and metrocytes, but no reactivity of anti-enolase 1 to the S. neurona bradyzoite stage despite reactivity to T. gondii bradyzoites, suggesting expression differences between organisms.
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Affiliation(s)
- K E Bolten
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, 601 Vernon Tharp Street, Columbus, OH 43210, USA
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Morley PS, Traub-Dargatz JL, Benedict KM, Saville WJA, Voelker LD, Wagner BA. Risk factors for owner-reported occurrence of equine protozoal myeloencephalitis in the US equine population. J Vet Intern Med 2008; 22:616-29. [PMID: 18466255 DOI: 10.1111/j.1939-1676.2008.0082.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Equine protozoal myeloencephalitis (EPM) is a serious and often fatal neurologic disease of horses, but few studies have investigated risk factors. OBJECTIVES To evaluate operation- and individual-level factors associated with likelihood of the occurrence of EPM. ANIMALS Data were collected as part of a study of the US equine industry from 1,178 operations representing 83.9% of horses and 51.6% of operations with > or =3 horses in 28 states. METHODS Probability-based sampling was used to enroll representative operations in a cross-sectional study. Interviews were conducted to collect information regarding health and management of horses. A nested case-control study was used to investigate risk factors among individual horses. Interview data were combined with climate data, human population density, and opossum regional ecology categories. Data were analyzed using logistic regression to identify risk factors for the occurrence of EPM. RESULTS Owners reported that 95% of EPM cases included in this study were diagnosed by veterinarians. Variables associated with EPM occurrence on premises included opossum regional ecology, reported exposure to small wildlife, climate, terrain, housing, choice of bedding material, method of storing feeds, equine stocking density, and primary use of horses. Among individual horses, age was most strongly associated with disease risk. Associations also were identified with sex, breed, primary use, and participation in competitions. CONCLUSIONS AND CLINICAL IMPORTANCE Because the risk of EPM occurrence on operations is closely tied to factors that impact exposure to opossums, their feces, and their environment, controlling these exposures may be important in preventing the occurrence of EPM.
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Affiliation(s)
- P S Morley
- Animal Population Health Institute, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80523, USA.
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Elitsur E, Marsh AE, Reed SM, Dubey JP, Oglesbee MJ, Murphy JE, Saville WJA. Early migration of Sarcocystis neurona in ponies fed sporocysts. J Parasitol 2008; 93:1222-5. [PMID: 18163363 DOI: 10.1645/ge-497r.1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Sarcocystis neurona is the most important cause of equine protozoal myeloencephalitis (EPM), a neurologic disease of the horse. In the present work, the kinetics of S. neurona invasion is determined in the equine model. Six ponies were orally inoculated with 250 x 10(6) S. neurona sporocysts via nasogastric intubation and killed on days 1, 2, 3, 5, 7, and 9 postinoculation (PI). At necropsy, tissue samples were examined for S. neurona infection. The parasite was isolated from the mesenteric lymph nodes at 1, 2, and 7 days PI; the liver at 2, 5, and 7 days PI; and the lungs at 5, 7, and 9 days PI by bioassays in interferon gamma gene knock out mice (KO) and from cell culture. Microscopic lesions consistent with an EPM infection were observed in brain and spinal cord of ponies killed 7 and 9 days PI. Results suggest that S. neurona disseminates quickly in tissue of naive ponies.
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Affiliation(s)
- E Elitsur
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210-1092, USA
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de Camps S, Dubey JP, Saville WJA. Seroepidemiology of Toxoplasma gondii in Zoo Animals in Selected Zoos in the Midwestern United States. J Parasitol 2008. [DOI: 10.1645/ge-1453r.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Klosterman E, Colitz CMH, Chandler HL, Kusewitt DF, Saville WJA, Dubielzig RR. Immunohistochemical properties of ocular adenomas, adenocarcinomas and medulloepitheliomas. Vet Ophthalmol 2006; 9:387-94. [PMID: 17076871 DOI: 10.1111/j.1463-5224.2006.00478.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ocular medulloepitheliomas, adenomas and adenocarcinomas share a common phenotype and originate from the optic cup neuroectoderm. This can make it very difficult to differentiate between these tumors histopathologically. Therefore, this study focused on identifying a combination of immunologic markers that might be used in the diagnosis of these tumors. These markers included AE1/AE3, CK7, CK20, and telomerase reverse transcriptase (TERT). Routine immunohistochemical staining was performed on 27 whole globes diagnosed with one of these tumors. The tumors that immunostained for TERT showed increasing immunoreactivity as the tumor types increased in aggressiveness. None of the tumor types were immunopositive for CK7. CK20 immunostaining was found in the adenomas but not in the adenocarcinomas or medulloepitheliomas. AE1/AE3 expression was present more consistently in the adenocarcinomas and less frequently in the adenomas. AE1/AE3 expression was present in only one of six medulloepitheliomas. Furthermore, CK20 and TERT showed inverse expression patterns, i.e. TERT increased in expression and CK20 decreased in expression with increasing aggressiveness. These results may be important diagnostic and prognostic indicators for these tumors.
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Affiliation(s)
- E Klosterman
- Department of Veterinary Clinical Sciences, The Ohio State University, College of Veterinary Medicine, Columbus, OH 43210, USA
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Furr M, McKenzie H, Saville WJA, Dubey JP, Reed SM, Davis W. PROPHYLACTIC ADMINISTRATION OF PONAZURIL REDUCES CLINICAL SIGNS AND DELAYS SEROCONVERSION IN HORSES CHALLENGED WITH SARCOCYSTIS NEURONA. J Parasitol 2006; 92:637-43. [PMID: 16884012 DOI: 10.1645/0022-3395(2006)92[637:paoprc]2.0.co;2] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The ability of ponazuril to prevent or limit clinical signs of equine protozoal myeloencephalitis (EPM) after infection with Sarcocystis neurona was evaluated. Eighteen horses were assigned to 1 of 3 groups: no treatment, 2.5 mg/kg ponazuril, or 5.0 mg/kg ponazuril. Horses were administered ponazuril, once per day, beginning 7 days before infection (study day 0) and continuing for 28 days postinfection. On day 0, horses were stressed by transport and challenged with 1 million S. neurona sporocysts per horse. Sequential neurologic examinations were performed, and serum and cerebrospinal fluid were collected and assayed for antibodies to S. neurona. All horses in the control group developed neurologic signs, whereas only 71 and 40% of horses in the 2.5 and 5.0 mg/kg ponazuril groups, respectively, developed neurologic abnormalities. This was significant at P = 0.034 by using Fisher exact test. In addition, seroconversion was decreased in the 5.0 mg/kg group compared with the control horses (100 vs. 40%; P = 0.028). Horses with neurologic signs were killed, and a post-mortem examination was performed. Mild-to-moderate, multifocal signs of neuroinflammation were observed. These results confirm that treatment with ponazuril at 5.0 mg/kg minimizes, but does not eliminate, infection and clinical signs of EPM in horses.
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Affiliation(s)
- M Furr
- Marion DuPont Scott Equine Medical Center, Virginia-Maryland Regional College of Veterinary Medicine, Leesburg, 20176, USA.
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Murphy JE, Marsh AE, Reed SM, Meadows C, Bolten K, Saville WJA. Development and evaluation of a Sarcocystis neurona-specific IgM capture enzyme-linked immunosorbent assay. J Vet Intern Med 2006; 20:322-8. [PMID: 16594589 DOI: 10.1892/0891-6640(2006)20[322:daeoas]2.0.co;2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Equine protozoal myeloencephalitis (EPM) is a serious neurologic disease of horses caused primarily by the protozoal parasite Sarcocystis neurona. Currently available antemortem diagnostic testing has low specificity. The hypothesis of this study was that serum and cerebrospinal fluid (CSF) of horses experimentally challenged with S neurona would have an increased S neurona-specific IgM (Sn-IgM) concentration after infection, as determined by an IgM capture enzyme linked immunoassay (ELISA). The ELISA was based on the S neurona low molecular weight protein SNUCD-1 antigen and the monoclonal antibody 2G5 labeled with horseradish peroxidase. The test was evaluated using serum and CSF from 12 horses experimentally infected with 1.5 million S neurona sporocysts and 16 horses experimentally infected with varying doses (100 to 100,000) of S neurona sporocysts, for which results of histopathologic examination of the central nervous system were available. For horses challenged with 1.5 million sporocysts, there was a significant increase in serum Sn-IgM concentrations compared with values before infection at weeks 2-6 after inoculation (P < .0001). For horses inoculated with lower doses of S neurona, there were significant increases in serum Sn-IgM concentration at various points in time after inoculation, depending on the challenge dose (P < .01). In addition, there was a significant increase between the CSF Sn-IgM concentrations before and after inoculation (P < .0001). These results support further evaluation of the assay as a diagnostic test during the acute phase of EPM.
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Affiliation(s)
- J E Murphy
- Department of' Clinical Sciences, The Ohio State University, Columbus, USA
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Saville WJA, Sofaly CD, Reed SM, Dubey JP, Oglesbee MJ, Lacombe VA, Keene RO, Gugisberg KM, Swensen SW, Shipley RD, Chiang YW, Chu HJ, Ng T. An equine protozoal myeloencephalitis challenge model testing a second transport after inoculation with Sarcocystis neurona sporocysts. J Parasitol 2005; 90:1406-10. [PMID: 15715237 DOI: 10.1645/ge-128r] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Previous challenge studies performed at Ohio State University involved a transport-stress model where the study animals were dosed with Sarcocystis neurona sporocysts on the day of arrival. This study was to test a second transportation of horses after oral inoculation with S. neurona sporocysts. Horses were assigned randomly to groups: group 1, transported 4 days after inoculation (DAI); group 2, at 11 DAI; group 3, at 18 DAI; and group 4, horses were not transported a second time (controls). An overall neurologic score was determined on the basis of a standard numbering system used by veterinarians. All scores are out of 5, which is the most severely affected animal. The mean score for the group 1 horses was 2.42; group 2 horses was 2.5; group 3 horses was 2.75; and group 4 horses was 3.25. Because the group 4 horses did not have a second transport, they were compared with all other groups. Statistically different scores were present between group 4 and groups 1 and 2. There was no difference in the time of seroconversion between groups. There was a difference between the time of onset of first clinical signs between groups 1 and 4. This difference was likely because of the different examination days. Differences in housing and handling were likely the reason for the differences in severity of clinical signs. This model results in consistent, significant clinical signs in all horses at approximately the same time period after inoculation but was most severe in horses that did not experience a second transport.
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Affiliation(s)
- W J A Saville
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210-1092, USA.
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Saville WJA, Dubey JP, Oglesbee MJ, Sofaly CD, Marsh AE, Elitsur E, Vianna MC, Lindsay DS, Reed SM. Experimental infection of ponies with Sarcocystis fayeri and differentiation from Sarcocystis neurona infections in horses. J Parasitol 2005; 90:1487-91. [PMID: 15715250 DOI: 10.1645/ge-313] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Sarcocystis neurona and Sarcocystis fayeri infections are common in horses in the Americas. Their antemortem diagnosis is important because the former causes a neurological disorder in horses, whereas the latter is considered nonpathogenic. There is a concern that equine antibodies to S. fayeri might react with S. neurona antigens in diagnostic tests. In this study, 4 ponies without demonstrable serum antibodies to S. neurona by Western immunoblot were used. Three ponies were fed 1 x 10(5) to 1 x 10(7) sporocysts of S. fayeri obtained from dogs that were fed naturally infected horse muscles. All ponies remained asymptomatic until the termination of the experiment, day 79 postinoculation (PI). All serum samples collected were negative for antibodies to S. neurona using the Western blot at the initial screening, just before inoculation with S. fayeri (day 2) and weekly until day 79 PI. Cerebrospinal fluid samples from each pony were negative for S. neurona antibodies. Using the S. neurona agglutination test, antibodies to S. neurona were not detected in 1:25 dilution of sera from any samples, except that from pony no. 4 on day 28; this pony had received 1 X 10(7) sporocysts. Using indirect immunofluorescence antibody tests (IFATs), 7 serum samples were found to be positive for S. neurona antibodies from 1:25 to 1:400 dilutions. Sarcocystis fayeri sarcocysts were found in striated muscles of all inoculated ponies, with heaviest infections in the tongue. All sarcocysts examined histologically appeared to contain only microcytes. Ultrastructurally, S. fayeri sarcocysts could be differentiated from S. neurona sarcocysts by the microtubules (mt) in villar protrusions on sarcocyst walls; in S. fayeri the mt extended from the villar tips to the pellicle of zoites, whereas in S. neurona the mt were restricted to the middle of the cyst wall. Results indicate that horses with S. fayeri infections may be misdiagnosed as being S. neurona infected using IFAT, and further research is needed on the serologic diagnosis of S. neurona infections.
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Affiliation(s)
- W J A Saville
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, Columbus, Ohio 43210-1092, USA.
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Stanek JF, Stich RW, Dubey JP, Reed SM, Njoku CJ, Lindsay DS, Schmall LM, Johnson GK, LaFave BM, Saville WJA. Epidemiology of Sarcocystis neurona infections in domestic cats (Felis domesticus) and its association with equine protozoal myeloencephalitis (EPM) case farms and feral cats from a mobile spay and neuter clinic. Vet Parasitol 2004; 117:239-49. [PMID: 14637026 DOI: 10.1016/j.vetpar.2003.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Equine protozoal myeloencephalitis (EPM) is a serious neurologic disease in the horse most commonly caused by Sarcocystis neurona. The domestic cat (Felis domesticus) is an intermediate host for S. neurona. In the present study, nine farms, known to have prior clinically diagnosed cases of EPM and a resident cat population were identified and sampled accordingly. In addition to the farm cats sampled, samples were also collected from a mobile spay and neuter clinic. Overall, serum samples were collected in 2001 from 310 cats, with samples including barn, feral and inside/outside cats. Of these 310 samples, 35 were from nine horse farms. Horse serum samples were also collected and traps were set for opossums at each of the farms. The S. neurona direct agglutination test (SAT) was used for both the horse and cat serum samples (1:25 dilution). Fourteen of 35 (40%) cats sampled from horse farms had circulating S. neurona agglutinating antibodies. Twenty-seven of the 275 (10%) cats from the spay/neuter clinic also had detectable S. neurona antibodies. Overall, 115 of 123 (93%) horses tested positive for anti-S. neurona antibodies, with each farm having greater than a 75% exposure rate among sampled horses. Twenty-one opossums were trapped on seven of the nine farms. Eleven opossums had Sarcocystis sp. sporocysts, six of them were identified as S. neurona sporocysts based on bioassays in gamma-interferon gene knockout mice with each opossum representing a different farm. Demonstration of S. neurona agglutinating antibodies in domestic and feral cats corroborates previous research demonstrating feral cats to be naturally infected, and also suggests that cats can be frequently infected with S. neurona and serve as one of several natural intermediate hosts for S. neurona.
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Affiliation(s)
- J F Stanek
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210-1092, USA
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Abstract
The purpose of this study was to estimate the amount of variation in milk urea nitrogen (MUN) concentrations attributable to test-day, individual cow, and herd effects and to describe factors associated with MUN measurements in Ohio dairy herds. The data came from 24 Holstein herds, half of which were classified as low producing (LP) [rolling herd average (RHA) milk production < 7,258 kg] and half as high producing (HP) herds (RHA production > 10,433 kg). MUN concentration was measured from cow's monthly test-day milk samples. The data were analyzed using multilevel modeling technique in MLwiN, separately for LP and HP herds. The unadjusted mean MUN was 13.9 mg/dl for the HP herds and 11.3 mg/dl for the LP herds. The variance structure was different between the two groups. Most of the variability was found at test-day level in the LP herds, but at herd level in HP herds. MUN was lowest during the first month of lactation, and also season was associated with MUN in both groups. Test-day milk yield, milk fat percentage, and SCC were associated with MUN in the HP herds. With significant explanatory variables in the model, proportionally more of the variation was explained at herd level and less at test day level in both groups. Lower variability in MUN between test days in the HP herds may indicate more consistent day-to-day feeding and management within a herd. The great variability between test days should be considered when interpreting MUN and samples should be collected at the same time of the day to minimize day-to-day variability.
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Affiliation(s)
- P J Rajala-Schultz
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, Ohio State University, A100L Sisson Hall, 1920 Coffey Road, Columbus, OH 43210, USA.
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Stanek JF, Dubey JP, Oglesbee MJ, Reed SM, Lindsay DS, Capitini LA, Njoku CJ, Vittitow KL, Saville WJA. Life Cycle of Sarcocystis neurona in Its Natural Intermediate Host, the Raccoon, Procyon lotor. J Parasitol 2002. [DOI: 10.2307/3285487] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Stanek JF, Dubey JP, Oglesbee MJ, Reed SM, Lindsay DS, Capitini LA, Njoku CJ, Vittitow KL, Saville WJA. Life cycle of Sarcocystis neurona in its natural intermediate host, the raccoon, Procyon lotor. J Parasitol 2002; 88:1151-8. [PMID: 12537110 DOI: 10.1645/0022-3395(2002)088[1151:lcosni]2.0.co;2] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Sarcocystis neurona causes encephalomyelitis in many species of mammals and is the most important cause of neurologic disease in the horse. Its complete life cycle is unknown, particularly its development and localization in the intermediate host. Recently, the raccoon (Procyon lotor) was recognized as a natural intermediate host of S. neurona. In the present study, migration and development of S. neurona was studied in 10 raccoons that were fed S. neurona sporocysts from experimentally infected opossums; 4 raccoons served as controls. Raccoons were examined at necropsy 1, 3, 5, 7, 10, 14, 15, 22, 37, and 77 days after feeding on sporocysts (DAFS). Tissue sections of most of the organs were studied histologically and reacted with anti-S. neurona-specific polyclonal rabbit serum in an immunohistochemical test. Parasitemia was demonstrated in peripheral blood of raccoons 3 and 5 DAFS. Individual zoites were seen in histologic sections of intestines of raccoons euthanized 1, 3, and 5 DAFS. Schizonts and merozoites were seen in many tissues 7 to 22 DAFS, particularly in the brain. Sarcocysts were seen in raccoons killed 22 DAFS. Sarcocysts at 22 DAFS were immature and seen only in skeletal muscle. Mature sarcocysts were seen in all skeletal samples, particularly in the tongue of the raccoon 77 DAFS; these sarcocysts were infective to laboratory-raised opossums. This is the first report of the complete development of S. neurona schizonts and sarcocysts in a natural intermediate host.
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Affiliation(s)
- J F Stanek
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, 1900 Coffey Road, Columbus, Ohio 43210-1092, USA
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Sofaly CD, Reed SM, Gordon JC, Dubey JP, Ogleebee MJ, Njoku CJ, Grover DL, Saville WJA. Experimental induction of equine protozoan myeloencephalitis (EPM) in the horse: effect of Sarcocystis neurona sporocyst inoculation dose on the development of clinical neurologic disease. J Parasitol 2002; 88:1164-70. [PMID: 12537112 DOI: 10.1645/0022-3395(2002)088[1164:eioepm]2.0.co;2] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The effect of inoculation dose of Sarcocystis neurona sporocysts on the development of clinical neurologic disease in horses was investigated. Twenty-four seronegative weanling horses were subjected to the natural stress of transport and then randomly assigned to 6 treatment groups of 4 horses each. Horses were then immediately inoculated with either 10(2), 10(3), 10(4), 10(5), or 10(6) S. neurona sporocysts or placebo using nasogastric tube and housed indoors. Weekly neurologic examinations were performed by a blinded observer. Blood was collected weekly for antibody determination by Western blot analysis. Cerebrospinal fluid was collected before inoculation and before euthanasia for S. neurona antibody determination. Horses were killed and necropsied between 4 and 5 wk after inoculation. Differences were detected among dose groups based on seroconversion times, severity of clinical neurologic signs, and presence of microscopic lesions. Seroconversion of challenged horses was observed as early as 14 days postinfection in the 10(6) sporocyst dose group. Mild to moderate clinical signs of neurologic disease were produced in challenged horses from all groups, with the most consistent signs seen in the 10(6) sporocyst dose group. Histologic lesions suggestive of S. neurona infection were detected in 4 of the 20 horses fed sporocysts. Parasites were not detected in equine tissues by light microscopy, immunohistochemistry, or bioassay in gamma-interferon gene knockout mice. Control horses remained seronegative for the duration of the study and had no histologic evidence of protozoal infection.
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Affiliation(s)
- C D Sofaly
- Department of Veterinary Preventive Medicine, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210-1092, USA
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Sofaly CD, Reed SM, Gordon JC, Dubey JP, Oglesbee MJ, Njoku CJ, Grover DL, Saville WJA. Experimental Induction of Equine Protozoan Myeloencephalitis (EPM) in the Horse: Effect of Sarcocystis neurona Sporocyst Inoculation Dose on the Development of Clinical Neurologic Disease. J Parasitol 2002. [DOI: 10.2307/3285489] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Abstract
Sarcocystis neurona is the most important cause of a neurologic disease of horses, equine protozoal myeloencephalitis (EPM). Cats and other carnivores can act as its intermediate hosts and horses are aberrant hosts. Little is known of the sero-epidemiology of S. neurona infections in cats. In the present study, antibodies to S. neurona were evaluated by the S. neurona agglutination test (SAT). Cats fed sporocysts from the feces of naturally infected opossums or inoculated intramuscularly with S. neurona merozoites developed high levels (> or =1:4000) of SAT antibodies. Antibodies to S. neurona were not found in a cat inoculated with merozoites of the closely related parasite, Sarcocystis falcatula. These results should be useful in studying sero-epidemiology of S. neurona infections in cats.
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Affiliation(s)
- J P Dubey
- United States Department of Agriculture, Agricultural Research Service, Animal and Natural Resources Institute, Parasite Biology, Epidemiology and Systematics Laboratory, Building 1001, Beltsville, MD 20705-2350, USA.
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Dubey JP, Saville WJA, Stanek JF, Reed SM. Prevalence of Toxoplasma gondii Antibodies in Domestic Cats from Rural Ohio. J Parasitol 2002. [DOI: 10.2307/3285366] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Abstract
Antibodies to Toxoplasma gondii were determined in serum samples from 275 domestic cats from a mobile spay and neuter clinic from 8 counties in Ohio. The modified agglutination test incorporating whole formalinized tachyzoites and mercaptoethanol was used to determine antibodies. Antibodies to T. gondii were found in 133 (48%) out of 275 cats: in titers of 1:25 in 24, 1:50 in 37, and 1:500 or more in 72. The highest prevalence (62% of 78) was in outdoor cats. The prevalence of T. gondii antibodies in 48% of cats suggests wide-spread contamination of the rural environment with oocysts.
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Affiliation(s)
- J P Dubey
- Parasite Biology, Epidemiology, and Systematics Laboratory, Building 1001, Animal and Natural Resources Institute, Agricultural Research Service, United States Department of Agriculture, Beltsville, Maryland 20705-2350, USA.
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Dubey JP, Rosypal AC, Rosenthal BM, Thomas NJ, Lindsay DS, Stanek JF, Reed SM, Saville WJA. Sarcocystis neurona Infections in Sea Otter (Enhydra lutris): Evidence for Natural Infections with Sarcocysts and Transmission of Infection to Opossums (Didelphis virginiana). J Parasitol 2001. [DOI: 10.2307/3285305] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Dubey JP, Saville WJA, Lindsay DS, Stich RW, Stanek JF, Speer CA, Rosenthal BM, Njoku CJ, Kwok OCH, Shen SK, Reed SM. Completion of the Life Cycle of Sarcocystis neurona. J Parasitol 2000. [DOI: 10.2307/3285013] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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