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Abstract. Seven members of a 15-man U.S. military team that had operated in rural Malaysia developed an acute illness consisting of fever, myalgias, bronchospasm, fleeting pruritic rashes, transient lymphadenopathy, and subcutaneous nodules associated with eosinophilia, elevated erythrocyte sedimentation rate, and elevated levels of muscle creatinine kinase. Sarcocysts of an unidentified Sarcocystis species were found in skeletal muscle biopsies of the index case. Albendazole ameliorated symptoms in the index case; however, his symptoms persisted for more than 5 years. Symptoms in 5 other men were mild to moderate and self-limited, and 1 team member with laboratory abnormalities was asymptomatic. Of 8 team members tested for antibody to Sarcocystis, 6 were positive; of 4 with the eosinophilic myositis syndrome who were tested, all were positive. We attribute this outbreak of eosinophilic myositis to accidental tissue parasitism by Sarcocystis.Human muscular sarcocystosis (syn. sarcosporidiosis) is a rare infection caused by coccidian parasites in the family Sarcocystidae. More than 100 different species of Sarcocystis occur worldwide in a wide range of domestic and wild animal reservoirs, with reported prevalences varying between 10% and 100% in domestic livestock.

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Abstract. Antigens of cultured Sarcocystis neurona merozoites were examined using immunoblot analysis. Blotted proteins were probed with S. cruzi, S. muris, and S. neurona antisera produced in rabbits, S. fayeri (pre-and post-infection) and S. neurona (pre-and post-inoculation) sera produced in horses, immune sera from 7 histologically confirmed cases of equine protozoa1 myeloencephalitis (EPM), and pre-suckle serum from a newborn foal. Eight proteins, 70, 24, 23.5, 22.5, 13, 11, 10.5, and 10 Kd, were detected only by S. neurona antiserum and/or immune serum from EPM-affected horses. Equine sera were titered by the indirect immunofluorescent antibody (IFA) method using air-dried, cultured S. neurona merozoites. Anti-Sarcocystis IFA titers were found in horses with or without EPM. Serum titers did not correspond to the number of specific bands recognized on immunoblots.Equine protozoa1 myeloencephalitis (EPM) is an often debilitating central nervous system (CNS) disease of the horse.9 It has been reported in horses native to North, 5 South, 1 and Central America. 6 The etiologic agent of EPM was recently cultured from naturally occurring cases in the US 2,3 and Panama 6 and named Sarcocystis neurona.Serological diagnosis of EPM caused by S. neurona has been complicated by the fact that species within the genus Sarcocystis share antigens. 4 For this reason, cross-reactions are observed when antigen from one species is recognized by serum antibody developed polyacrylamide gel electrophoresis (SDS-PAGE) in 0.75 mm, vertical, 5-20% or 10-20% linear gradient polyacrylamide resolving gels and 4% stacking gels using a discontinuous buffer method 8 and silver stained. 7 High-and low-range molecular weight markers were included in separate lanes. Immunoblots were prepared using 1 x 10 7 solubilized merozoites separated in 1 -well SDS-PAGE gels. Separated proteins were electrophoretically transferred to 0.45 µm nitrocellulose in Towbin buffer (0.192 M glycine, 0.025 M tris pH 8.3, 20% v/v methanol) using 1.0 A constant current for 1 hr. Prestained molecular weight markers were used in a separate lane.c Blotting efficiency was demonstrated by India ink staining of the blot and Coomassie blue staining of the against another species. The objective of this study was transferred gel.7 Blots were blocked with 5% non-fat dry milk, to identify S. neurona-specific proteins for antemortem 0.1% nonionic emulsifier, d and 0.1% sodium azide in 0.01 diagnostic use that would not cross-react with antibody M PBS, pH 7.2 for 1 hr and subdivided into lanes using a against other species. molded plexiglass press. e Each of the following sera were diluted in blocking buffer and incubated for 2 hr in individual Materials and methods lanes: S. cruzi (bradyzoites), S. muris (bradyzoites), and S.Sarcocystis neurona merozoites were harvested from boneurona (merozoites) antisera prepared in rabbits 7 normal vine monocyte (M617) cell cultures and purified on an isosrabbit serum, S. faveri (pre-and post-infection) and S. neumotic colloidal silica a st...

Sarcocystis neurona is an apicomplexan that causes equine protozoal myeloencephalitis (EPM) in North and South America. Horses appear to be an aberrant host, because the merozoites continually divide in the central nervous system, without encysting. The natural host species has not previously been identified. The small subunit ribosomal RNA (SSURNA) gene of S. neurona was compared to those of Sarcocystis muris, Sarcocystis cruzi, Toxoplasma gondii, and Cryptosporidium parvum to identify a unique region suitable for a species-specific amplification primer. The S. neurona SSURNA primer was used in a polymerase chain reaction (PCR) assay for the purpose of identifying this organism in feces and intestinal digest of wildlife specimens. Sporocysts were isolated from 4 raccoons (Procyon lotor), 2 opossums (Didelphis virginiana), 7 skunks (Mephitis mephitis), 6 cats (Felis catus), 1 hawk (Accipiter sp.), and 1 coyote (Canis latrans). The S. neurona SSURNA PCR assay and a control PCR assay using protist-specific primers were applied to all sporocyst DNA samples. All sporocyst DNA samples tested positive on the control assay. The SSURNA PCR assay yielded a 484-bp product only when applied to opossum samples. The SSURNA gene of both opossum sporocyst samples was sequenced to determine its relationship to the S. neurona SSURNA gene. The sequence had 99.89% similarity with S. neurona. This suggests that opossums are the definitive host of S. neurona.