FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Vet Parasitol / Molecular characterization of Sarcocystis neurona strains fr...
Veterinary parasitology2010; 170(1-2); 20-29; doi: 10.1016/j.vetpar.2009.12.045

Molecular characterization of Sarcocystis neurona strains from opossums (Didelphis virginiana) and intermediate hosts from Central California.

Abstract: Sarcocystis neurona is a significant cause of neurological disease in horses and other animals, including the threatened Southern sea otter (Enhydra lutris nereis). Opossums (Didelphis virginiana), the only known definitive hosts for S. neurona in North America, are an introduced species in California. S. neurona DNA isolated from sporocysts and/or infected tissues of 10 opossums, 6 horses, 1 cat, 23 Southern sea otters, and 1 harbor porpoise (Phocoena phocoena) with natural infections was analyzed based on 15 genetic markers, including the first internal transcribed spacer (ITS-1) region; the 25/396 marker; S. neurona surface antigen genes (snSAGs) 2, 3, and 4; and 10 different microsatellites. Based on phylogenetic analysis, most of the S. neurona strains segregated into three genetically distinct groups. Additionally, fifteen S. neurona samples from opossums and several intermediate hosts, including sea otters and horses, were found to be genetically identical across all 15 genetic markers, indicating that fatal encephalitis in Southern sea otters and equine protozoal myeloencephalitis (EPM) in horses is strongly linked to S. neurona sporocysts shed by opossums.
(c) 2010 Elsevier B.V. All rights reserved.
Get Full Text
Publication Date: 2010-02-11 PubMed ID: 20226596PubMed Central: PMC4878691DOI: 10.1016/j.vetpar.2009.12.045Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article
  • Research Support
  • N.I.H.
  • Intramural
  • Research Support
  • Non-U.S. Gov't

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The study investigates the characteristics of Sarcocystis neurona, a pathogen causing neurological diseases in horses and other animals, in different hosts. The study reveals fatal encephalitis in Southern sea otters and equine protozoal myeloencephalitis in horses strongly link to S. neurona sporocysts shed by opossums.

Objective of the Research

  • The main aim of this research was to understand the molecular characteristics of the Sarcocystis neurona strains in different host species. Scientists endeavored to determine any genetic difference among the S. neurona strains isolated from different hosts.

Methodology

  • The S. neurona DNA was isolated from the sporocysts and/or infected tissues of various host species. The hosts include 10 opossums, 6 horses, 1 cat, 23 Southern sea otters, and 1 harbor porpoise, all with natural infections.
  • A total of 15 genetic markers were analyzed, comprising the first internal transcribed spacer (ITS-1) region, the 25/396 marker, S. neurona surface antigen genes (snSAGs) 2, 3, and 4, and 10 different microsatellites.

Findings

  • The phylogenetic analysis led to the identification of three primary genetically distinct groups of S. neurona strains.
  • Interestingly, fifteen S. neurona samples derived from opossums and several intermediate hosts, like sea otters and horses, were found to be genetically identical across all 15 genetic markers.

Implications

  • This genetic similarity across the hosts indicates that fatal encephalitis in Southern sea otters and equine protozoal myeloencephalitis (EPM) in horses are most likely caused by S. neurona sporocysts shed by opossums.
  • This finding is significant for the implementation and development of control and treatment strategies against these diseases.
  • The study highlights the importance of addressing the ecological role of opossums in the spread and perpetuation of S. neurona in the environment.

Cite This Article

APA
Rejmanek D, Miller MA, Grigg ME, Crosbie PR, Conrad PA. (2010). Molecular characterization of Sarcocystis neurona strains from opossums (Didelphis virginiana) and intermediate hosts from Central California. Vet Parasitol, 170(1-2), 20-29. https://doi.org/10.1016/j.vetpar.2009.12.045

Publication

Veterinary parasitology
ISSN: 1873-2550
NlmUniqueID: 7602745
Country: Netherlands
Language: English
Volume: 170
Issue: 1-2
Pages: 20-29

Researcher Affiliations

Rejmanek, Daniel
  • Department of Pathology, Microbiology, and Immunology, School of Veterinary Medicine, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA. drejmanek@ucdavis.edu
Miller, Melissa A
    Grigg, Michael E
      Crosbie, Paul R
        Conrad, Patricia A

          MeSH Terms

          • Amino Acid Sequence
          • Animals
          • Antigens, Protozoan / chemistry
          • Antigens, Protozoan / genetics
          • Base Sequence
          • California / epidemiology
          • Conservation of Natural Resources
          • DNA, Protozoan / chemistry
          • DNA, Protozoan / genetics
          • DNA, Ribosomal Spacer / chemistry
          • DNA, Ribosomal Spacer / genetics
          • Microsatellite Repeats / genetics
          • Molecular Sequence Data
          • Opossums / parasitology
          • Otters / parasitology
          • Phylogeny
          • Polymerase Chain Reaction / veterinary
          • Polymorphism, Genetic / genetics
          • Sarcocystis / classification
          • Sarcocystis / genetics
          • Sarcocystis / isolation & purification
          • Sarcocystosis / epidemiology
          • Sarcocystosis / parasitology
          • Sarcocystosis / veterinary
          • Sequence Alignment
          • Sequence Analysis, DNA

          Grant Funding

          • Z01 AI001017-02 / Intramural NIH HHS

          References

          This article includes 58 references
          1. Asmundsson IM, Dubey JP, Rosenthal BM. A genetically diverse but distinct North American population of Sarcocystis neurona includes an overrepresented clone described by 12 microsatellite alleles.. Infect Genet Evol 2006 Sep;6(5):352-60.
            pubmed: 16488197doi: 10.1016/j.meegid.2006.01.001google scholar: lookup
          2. Asmundsson IM, Rosenthal BM. Isolation and characterization of microsatellite markers from Sarcocystis neurona, a causative agent of equine protozoal myeloencephalitis.. Mol. Ecol. Notes 2006;6:8–10.
          3. Boothroyd JC. Expansion of host range as a driving force in the evolution of Toxoplasma.. Mem Inst Oswaldo Cruz 2009 Mar;104(2):179-84.
            pubmed: 19430641doi: 10.1590/s0074-02762009000200009google scholar: lookup
          4. Butcher M, Lakritz J, Halaney A, Branson K, Gupta GD, Kreeger J, Marsh AE. Experimental inoculation of domestic cats (Felis domesticus) with Sarcocystis neurona or S. neurona-like merozoites.. Vet Parasitol 2002 Jul 29;107(1-2):1-14.
            pubmed: 12072209doi: 10.1016/s0304-4017(02)00107-3google scholar: lookup
          5. Cohen ND, Mackay RJ, Toby E, Andrews FM, Barr BS, Beech J, Bernard WV, Clark CK, Divers TJ, Furr MO, Kohn CW, Levy M, Reed SM, Seahorn TL, Slovis NM. A multicenter case-control study of risk factors for equine protozoal myeloencephalitis.. J Am Vet Med Assoc 2007 Dec 15;231(12):1857-63.
            pubmed: 18081525doi: 10.2460/javma.231.12.1857google scholar: lookup
          6. Cooley AJ, Barr B, Rejmanek D. Sarcocystis neurona encephalitis in a dog.. Vet Pathol 2007 Nov;44(6):956-61.
            pubmed: 18039914doi: 10.1354/vp.44-6-956google scholar: lookup
          7. Dzierszinski F, Mortuaire M, Cesbron-Delauw MF, Tomavo S. Targeted disruption of the glycosylphosphatidylinositol-anchored surface antigen SAG3 gene in Toxoplasma gondii decreases host cell adhesion and drastically reduces virulence in mice.. Mol Microbiol 2000 Aug;37(3):574-82.
            pubmed: 10931351doi: 10.1046/j.1365-2958.2000.02014.xgoogle scholar: lookup
          8. Dubey JP, Davis SW, Speer CA, Bowman DD, de Lahunta A, Granstrom DE, Topper MJ, Hamir AN, Cummings JF, Suter MM. Sarcocystis neurona n. sp. (Protozoa: Apicomplexa), the etiologic agent of equine protozoal myeloencephalitis.. J Parasitol 1991 Apr;77(2):212-8.
            pubmed: 1901359
          9. Dubey JP, Hamir AN. Immunohistochemical confirmation of Sarcocystis neurona infections in raccoons, mink, cat, skunk, and pony.. J Parasitol 2000 Oct;86(5):1150-2.
            pubmed: 11128499doi: 10.1645/0022-3395(2000)086[1150:icosni]2.0.co;2google scholar: lookup
          10. Dubey JP, Lindsay DS, Saville WJ, Reed SM, Granstrom DE, Speer CA. A review of Sarcocystis neurona and equine protozoal myeloencephalitis (EPM).. Vet Parasitol 2001 Feb 26;95(2-4):89-131.
            pubmed: 11223193doi: 10.1016/s0304-4017(00)00384-8google scholar: lookup
          11. Dubey JP, Saville WJ, Sreekumar C, Shen SK, Lindsay OS, Pena HF, Vianna MC, Gennari SM, Reed SM. Effects of high temperature and disinfectants on the viability of Sarcocystis neurona sporocysts.. J Parasitol 2002 Dec;88(6):1252-4.
            pubmed: 12537123doi: 10.1645/0022-3395(2002)088[1252:eohtad]2.0.co;2google scholar: lookup
          12. Dubey JP, Speer CA, Fayer R. Sarcocystosis of Animals and Man. Boca Raton, FL: CRC Press; 1989.
          13. Elsheikha HM, Mansfield LS. Sarcocystis neurona major surface antigen gene 1 (SAG1) shows evidence of having evolved under positive selection pressure.. Parasitol Res 2004 Dec;94(6):452-9.
            pubmed: 15517384doi: 10.1007/s00436-004-1237-ygoogle scholar: lookup
          14. Elsheikha HM, Murphy AJ, Mansfield LS. Viability of Sarcocystis neurona sporocysts after long-term storage.. Vet Parasitol 2004 Sep 2;123(3-4):257-64.
            pubmed: 15325051doi: 10.1016/j.vetpar.2004.06.013google scholar: lookup
          15. Elsheikha HM, Murphy AJ, Mansfield LS. Phylogenetic congruence of Sarcocystis neurona Dubey et al., 1991 (Apicomplexa: Sarcocystidae) in the United States based on sequence analysis and restriction fragment length polymorphism (RFLP).. Syst Parasitol 2005 Jul;61(3):191-202.
            pubmed: 16025209doi: 10.1007/s11230-005-3163-5google scholar: lookup
          16. Elsheikha HM. Has Sarcocystis neurona Dubey et al., 1991 (Sporozoa: Apicomplexa: Sarcocystidae) cospeciated with its intermediate hosts?. Vet Parasitol 2009 Aug 26;163(4):307-14.
            pubmed: 19375231doi: 10.1016/j.vetpar.2009.03.019google scholar: lookup
          17. Fayer R, Mayhew IG, Baird JD, Dill SG, Foreman JH, Fox JC, Higgins RJ, Reed SM, Ruoff WW, Sweeney RW. Epidemiology of equine protozoal myeloencephalitis in North America based on histologically confirmed cases. A report.. J Vet Intern Med 1990 Mar-Apr;4(2):54-7.
            pubmed: 2342022doi: 10.1111/j.1939-1676.1990.tb03103.xgoogle scholar: lookup
          18. Felsenstein J. PHYLIP—Phylogeny Inference Package (Version 3.2). Cladistics 1989;5:164–166.
          19. Felsenstein J, Churchill GA. A Hidden Markov Model approach to variation among sites in rate of evolution.. Mol Biol Evol 1996 Jan;13(1):93-104.
            pubmed: 8583911doi: 10.1093/oxfordjournals.molbev.a025575google scholar: lookup
          20. Fitch WM. Toward defining the course of evolution: minimum change for a specified tree topology.. Syst. Zool. 1971;20:406–416.
          21. Goldstein DB, Ruiz Linares A, Cavalli-Sforza LL, Feldman MW. An evaluation of genetic distances for use with microsatellite loci.. Genetics 1995 Jan;139(1):463-71.
            pmc: PMC1206344pubmed: 7705647doi: 10.1093/genetics/139.1.463google scholar: lookup
          22. Grigg ME, Ganatra J, Boothroyd JC, Margolis TP. Unusual abundance of atypical strains associated with human ocular toxoplasmosis.. J Infect Dis 2001 Sep 1;184(5):633-9.
            pubmed: 11474426doi: 10.1086/322800google scholar: lookup
          23. Grigg ME, Sundar N. Sexual recombination punctuated by outbreaks and clonal expansions predicts Toxoplasma gondii population genetics.. Int J Parasitol 2009 Jul 1;39(8):925-33.
            pmc: PMC2713429pubmed: 19217909doi: 10.1016/j.ijpara.2009.02.005google scholar: lookup
          24. Grinnell J, Dixon JS, Linsdale JM. Fur-bearing Mammals of California. Berkeley, CA: University of California Press; 1937. pp. 47–60.
          25. Howe DK, Sibley LD. Toxoplasma gondii comprises three clonal lineages: correlation of parasite genotype with human disease.. J Infect Dis 1995 Dec;172(6):1561-6.
            pubmed: 7594717doi: 10.1093/infdis/172.6.1561google scholar: lookup
          26. Howe DK, Gaji RY, Mroz-Barrett M, Gubbels MJ, Striepen B, Stamper S. Sarcocystis neurona merozoites express a family of immunogenic surface antigens that are orthologues of the Toxoplasma gondii surface antigens (SAGs) and SAG-related sequences.. Infect Immun 2005 Feb;73(2):1023-33.
            pmc: PMC546929pubmed: 15664946doi: 10.1128/iai.73.2.1023-1033.2005google scholar: lookup
          27. Howe DK, Gaji RY, Marsh AE, Patil BA, Saville WJ, Lindsay DS, Dubey JP, Granstrom DE. Strains of Sarcocystis neurona exhibit differences in their surface antigens, including the absence of the major surface antigen SnSAG1.. Int J Parasitol 2008 May;38(6):623-31.
            pubmed: 17980881doi: 10.1016/j.ijpara.2007.09.007google scholar: lookup
          28. Hyun C, Gupta GD, Marsh AE. Sequence comparison of Sarcocystis neurona surface antigen from multiple isolates.. Vet Parasitol 2003 Feb 28;112(1-2):11-20.
            pubmed: 12581581doi: 10.1016/s0304-4017(02)00392-8google scholar: lookup
          29. Johnson CK, Tinker MT, Estes JA, Conrad PA, Staedler M, Miller MA, Jessup DA, Mazet JA. Prey choice and habitat use drive sea otter pathogen exposure in a resource-limited coastal system.. Proc Natl Acad Sci U S A 2009 Feb 17;106(7):2242-7.
            pmc: PMC2650139pubmed: 19164513doi: 10.1073/pnas.0806449106google scholar: lookup
          30. Jung C, Lee CY, Grigg ME. The SRS superfamily of Toxoplasma surface proteins.. Int J Parasitol 2004 Mar 9;34(3):285-96.
            pubmed: 15003490doi: 10.1016/j.ijpara.2003.12.004google scholar: lookup
          31. Kreuder C, Miller MA, Jessup DA, Lowenstine LJ, Harris MD, Ames JA, Carpenter TE, Conrad PA, Mazet JA. Patterns of mortality in southern sea otters (Enhydra lutris nereis) from 1998-2001.. J Wildl Dis 2003 Jul;39(3):495-509.
            pubmed: 14567210doi: 10.7589/0090-3558-39.3.495google scholar: lookup
          32. Larkin MA, Blackshields G, Brown NP, Chenna R, McGettigan PA, McWilliam H, Valentin F, Wallace IM, Wilm A, Lopez R, Thompson JD, Gibson TJ, Higgins DG. Clustal W and Clustal X version 2.0.. Bioinformatics 2007 Nov 1;23(21):2947-8.
            pubmed: 17846036doi: 10.1093/bioinformatics/btm404google scholar: lookup
          33. Lekutis C, Ferguson DJ, Grigg ME, Camps M, Boothroyd JC. Surface antigens of Toxoplasma gondii: variations on a theme.. Int J Parasitol 2001 Oct;31(12):1285-92.
            pubmed: 11566296doi: 10.1016/s0020-7519(01)00261-2google scholar: lookup
          34. Lindsay DS, Thomas NJ, Dubey JP. Biological characterisation of Sarcocystis neurona isolated from a Southern sea otter (Enhydra lutris nereis).. Int J Parasitol 2000 Apr 24;30(5):617-24.
            pubmed: 10779575doi: 10.1016/s0020-7519(00)00034-5google scholar: lookup
          35. Lindsay DS, Collins MV, Mitchell SM, Cole RA, Flick GJ, Wetch CN, Lindquist A, Dubey JP. Sporulation and survival of Toxoplasma gondii oocysts in seawater.. J Eukaryot Microbiol 2003;50 Suppl:687-8.
            pubmed: 14736220doi: 10.1111/j.1550-7408.2003.tb00688.xgoogle scholar: lookup
          36. Marsh AE, Barr BC, Madigan J, Lakritz J, Conrad PA. Sequence analysis and polymerase chain reaction amplification of small subunit ribosomal DNA from Sarcocystis neurona.. Am J Vet Res 1996 Jul;57(7):975-81.
            pubmed: 8807006
          37. Marsh AE, Howe DK, Wang G, Barr BC, Cannon N, Conrad PA. Differentiation of Neospora hughesi from Neospora caninum based on their immunodominant surface antigen, SAG1 and SRS2.. Int J Parasitol 1999 Oct;29(10):1575-82.
            pubmed: 10608444doi: 10.1016/s0020-7519(99)00120-4google scholar: lookup
          38. Marsh AE, Johnson PJ, Ramos-Vara J, Johnson GC. Characterization of a Sarcocystis neurona isolate from a Missouri horse with equine protozoal myeloencephalitis.. Vet Parasitol 2001 Feb 26;95(2-4):143-54.
            pubmed: 11223195doi: 10.1016/s0304-4017(00)00386-1google scholar: lookup
          39. Martins WS, Lucas DC, Neves KF, Bertioli DJ. WebSat--a web software for microsatellite marker development.. Bioinformation 2009;3(6):282-3.
            pmc: PMC2646864pubmed: 19255650doi: 10.6026/97320630003282google scholar: lookup
          40. Miller MA, Sverlow K, Crosbie PR, Barr BC, Lowenstine LJ, Gulland FM, Packham A, Conrad PA. Isolation and characterization of two parasitic protozoa from a Pacific harbor seal (Phoca vitulina richardsi) with meningoencephalomyelitis.. J Parasitol 2001 Aug;87(4):816-22.
            pubmed: 11534647doi: 10.1645/0022-3395(2001)087[0816:iacotp]2.0.co;2google scholar: lookup
          41. Miller NL, Frenkel JK, Dubey JP. Oral infections with Toxoplasma cysts and oocysts in felines, other mammals, and in birds.. J Parasitol 1972 Oct;58(5):928-37.
            pubmed: 5078599
          42. Mondragon R, Howe DK, Dubey JP, Sibley LD. Genotypic analysis of Toxoplasma gondii isolates from pigs.. J Parasitol 1998 Jun;84(3):639-41.
            pubmed: 9645877
          43. Murphy AJ, Mansfield LS. Simplified technique for isolation, excystation, and culture of Sarcocystis species from opossums.. J Parasitol 1999 Oct;85(5):979-81.
            pubmed: 10577742
          44. Owen MR, Trees AJ. Vertical transmission of Toxoplasma gondii from chronically infected house (Mus musculus) and field (Apodemus sylvaticus) mice determined by polymerase chain reaction.. Parasitology 1998 Apr;116 ( Pt 4):299-304.
            pubmed: 9585931doi: 10.1017/s003118209700231xgoogle scholar: lookup
          45. Page RD. TreeView: an application to display phylogenetic trees on personal computers.. Comput Appl Biosci 1996 Aug;12(4):357-8.
            pubmed: 8902363doi: 10.1093/bioinformatics/12.4.357google scholar: lookup
          46. Rejmanek D, Vanwormer E, Miller MA, Mazet JA, Nichelason AE, Melli AC, Packham AE, Jessup DA, Conrad PA. Prevalence and risk factors associated with Sarcocystis neurona infections in opossums (Didelphis virginiana) from central California.. Vet Parasitol 2009 Dec 3;166(1-2):8-14.
            pubmed: 19735983doi: 10.1016/j.vetpar.2009.08.013google scholar: lookup
          47. Saitou N, Nei M. The neighbor-joining method: a new method for reconstructing phylogenetic trees.. Mol Biol Evol 1987 Jul;4(4):406-25.
            pubmed: 3447015doi: 10.1093/oxfordjournals.molbev.a040454google scholar: lookup
          48. Saville WJ, Reed SM, Morley PS, Granstrom DE, Kohn CW, Hinchcliff KW, Wittum TE. Analysis of risk factors for the development of equine protozoal myeloencephalitis in horses.. J Am Vet Med Assoc 2000 Oct 15;217(8):1174-80.
            pubmed: 11043688doi: 10.2460/javma.2000.217.1174google scholar: lookup
          49. Shriver MD, Jin L, Boerwinkle E, Deka R, Ferrell RE, Chakraborty R. A novel measure of genetic distance for highly polymorphic tandem repeat loci.. Mol Biol Evol 1995 Sep;12(5):914-20.
            pubmed: 7476137doi: 10.1093/oxfordjournals.molbev.a040268google scholar: lookup
          50. Slatkin M. A measure of population subdivision based on microsatellite allele frequencies.. Genetics 1995 Jan;139(1):457-62.
            pmc: PMC1206343pubmed: 7705646doi: 10.1093/genetics/139.1.457google scholar: lookup
          51. Su C, Evans D, Cole RH, Kissinger JC, Ajioka JW, Sibley LD. Recent expansion of Toxoplasma through enhanced oral transmission.. Science 2003 Jan 17;299(5605):414-6.
            pubmed: 12532022doi: 10.1126/science.1078035google scholar: lookup
          52. Sundar N, Asmundsson IM, Thomas NJ, Samuel MD, Dubey JP, Rosenthal BM. Modest genetic differentiation among North American populations of Sarcocystis neurona may reflect expansion in its geographic range.. Vet Parasitol 2008 Mar 25;152(1-2):8-15.
            pubmed: 18243561doi: 10.1016/j.vetpar.2007.12.017google scholar: lookup
          53. Swofford D. PAUP*. Phylogenetic Analysis Using Parsimony (*and Other Methods). Sunderland, MA: Sinauer Associates; 2003.
          54. Tanhauser SM, Yowell CA, Cutler TJ, Greiner EC, MacKay RJ, Dame JB. Multiple DNA markers differentiate Sarcocystis neurona and Sarcocystis falcatula.. J Parasitol 1999 Apr;85(2):221-8.
            pubmed: 10219299
          55. Tenter AM, Heckeroth AR, Weiss LM. Toxoplasma gondii: from animals to humans.. Int J Parasitol 2000 Nov;30(12-13):1217-58.
            pmc: PMC3109627pubmed: 11113252doi: 10.1016/s0020-7519(00)00124-7google scholar: lookup
          56. Thomas NJ, Dubey JP, Lindsay DS, Cole RA, Meteyer CU. Protozoal meningoencephalitis in sea otters (Enhydra lutris): a histopathological and immunohistochemical study of naturally occurring cases.. J Comp Pathol 2007 Aug-Oct;137(2-3):102-21.
            pubmed: 17692867doi: 10.1016/j.jcpa.2007.05.001google scholar: lookup
          57. Turay HO, Barr BC, Caldwell A, Branson KR, Cockrell MK, Marsh AE. Sarcocystis neurona reacting antibodies in Missouri feral domestic cats (Felis domesticus) and their role as an intermediate host.. Parasitol Res 2002 Jan;88(1):38-43.
            pubmed: 11826870doi: 10.1007/s004360100503google scholar: lookup
          58. Wendte JM, Miller MA, Nandra AK, Peat SM, Crosbie PR, Conrad PA, Grigg ME. Limited genetic diversity among Sarcocystis neurona strains infecting southern sea otters precludes distinction between marine and terrestrial isolates.. Vet Parasitol 2010 Apr 19;169(1-2):37-44.
            pmc: PMC2858970pubmed: 20071081doi: 10.1016/j.vetpar.2009.12.020google scholar: lookup

          Citations

          This article has been cited 9 times.
          1. Dzido J, Rolbiecki L, Izdebska JN, Rokicki J, Kuczkowski T, Pawliczka I. A global checklist of the parasites of the harbor porpoise Phocoena phocoena, a critically-endangered species, including new findings from the Baltic Sea. Int J Parasitol Parasites Wildl 2021 Aug;15:290-302.
            doi: 10.1016/j.ijppaw.2021.07.002pubmed: 34336594google scholar: lookup
          2. O'Byrne AM, Lambourn DM, Rejmanek D, Haman K, O'Byrne M, VanWormer E, Shapiro K. Sarcocystis neurona Transmission from Opossums to Marine Mammals in the Pacific Northwest. Ecohealth 2021 Mar;18(1):84-94.
            doi: 10.1007/s10393-021-01536-wpubmed: 34213686google scholar: lookup
          3. Girard YA, Johnson CK, Fritz HM, Shapiro K, Packham AE, Melli AC, Carlson-Bremer D, Gulland FM, Rejmanek D, Conrad PA. Detection and characterization of diverse coccidian protozoa shed by California sea lions. Int J Parasitol Parasites Wildl 2016 Apr;5(1):5-16.
            doi: 10.1016/j.ijppaw.2015.11.003pubmed: 27141438google scholar: lookup
          4. Barbosa L, Johnson CK, Lambourn DM, Gibson AK, Haman KH, Huggins JL, Sweeny AR, Sundar N, Raverty SA, Grigg ME. A novel Sarcocystis neurona genotype XIII is associated with severe encephalitis in an unexpectedly broad range of marine mammals from the northeastern Pacific Ocean. Int J Parasitol 2015 Aug;45(9-10):595-603.
            doi: 10.1016/j.ijpara.2015.02.013pubmed: 25997588google scholar: lookup
          5. Dubey JP, Howe DK, Furr M, Saville WJ, Marsh AE, Reed SM, Grigg ME. An update on Sarcocystis neurona infections in animals and equine protozoal myeloencephalitis (EPM). Vet Parasitol 2015 Apr 15;209(1-2):1-42.
            doi: 10.1016/j.vetpar.2015.01.026pubmed: 25737052google scholar: lookup
          6. Oates SC, Miller MA, Hardin D, Conrad PA, Melli A, Jessup DA, Dominik C, Roug A, Tinker MT, Miller WA. Prevalence, environmental loading, and molecular characterization of Cryptosporidium and Giardia isolates from domestic and wild animals along the Central California Coast. Appl Environ Microbiol 2012 Dec;78(24):8762-72.
            doi: 10.1128/AEM.02422-12pubmed: 23042185google scholar: lookup
          7. Wendte JM, Gibson AK, Grigg ME. Population genetics of Toxoplasma gondii: new perspectives from parasite genotypes in wildlife. Vet Parasitol 2011 Nov 24;182(1):96-111.
            doi: 10.1016/j.vetpar.2011.07.018pubmed: 21824730google scholar: lookup
          8. Wendte JM, Miller MA, Lambourn DM, Magargal SL, Jessup DA, Grigg ME. Self-mating in the definitive host potentiates clonal outbreaks of the apicomplexan parasites Sarcocystis neurona and Toxoplasma gondii. PLoS Genet 2010 Dec 23;6(12):e1001261.
            doi: 10.1371/journal.pgen.1001261pubmed: 21203443google scholar: lookup
          9. Sinnott DM, Miller MA, VanWormer E, Batac F, Greenwald K, Young C, Duignan PJ, Martinez ME, Field CL, Harris MD, Harris H, Gomes ME, Murray MJ, Shapiro K. Parasite genotype is a risk factor for Sarcocystis neurona-associated mortality in southern sea otters (Enhydra lutris nereis). Int J Parasitol Parasites Wildl 2026 Apr;29:101174.
            doi: 10.1016/j.ijppaw.2025.101174pubmed: 41458918google scholar: lookup
          Subscribe to our newsletter
          Join 99,383 horse owners like you who receive our email updates on horse health and nutrition.