Meningoencephalitis caused by concurrent infection with canine distemper virus and a unique Sarcocystis sp. in a gray fox.

A deceased 9-wk-old male gray fox (Urocyon cinereoargenteus) with a history of decreased ambulation and diarrhea was submitted to the Texas A&M Veterinary Medical Diagnostic Laboratory. No significant gross findings were evident on postmortem examination. Histologically, the cerebrum and brainstem had mild necrotizing meningoencephalitis with protozoal schizonts and merozoites. Additionally, glial cells contained intracytoplasmic and intranuclear viral inclusion bodies. Sections of the cerebrum were positive for canine distemper virus (CDV) and negative for Sarcocystis neurona on immunohistochemistry. Bayesian analysis revealed that this Sarcocystis sp. clustered most closely with a clade of unnamed Sarcocystis sp. found in viperid snakes, with a posterior probability of 99%. CDV likely played a significant role in the expression of clinical sarcocystosis in this gray fox.

Fatal Sarcocystis calchasi-associated meningoencephalitis in 2 captive vulturine guineafowl.

Two captive vulturine guineafowl (Acryllium vulturinum) were presented with lethargy, hyporexia, weight loss, and progressive neurologic signs. One of the guineafowl was seropositive for Sarcocystis falcatula (1:50 dilution). Both guineafowl died within 5 d of presentation. Histologic examination revealed nonsuppurative meningoencephalitis with gliosis, associated with occasional schizonts in the neuropil. Using fresh-frozen brain tissue, PCR was performed to amplify the ITS1 RNA region and portions of the 18S ribosomal RNA gene (18S gene) and the 28S ribosomal RNA gene (28S gene). Analysis of nucleic acid sequences from the resulting amplicons indicated that Sarcocystis calchasi was the likely cause of disease. To our knowledge, S. calchasi-associated disease has not been reported previously in the order Galliformes.

Lesions caused by Sarcocystis spp., parasites of opossums (Didelphis aurita), in acute and chronic infections in birds (Melopsittacus undulatus).

Protozoa of the genus Sarcocystis are obligatory heterogenous parasites with both definitive and intermediate hosts. Opossums (Didelphis aurita) can shed multiple species of Sarcocystis with birds as the intermediate host. The pathologies of Sarcocystis species in birds have not been thoroughly elucidated. Therefore, the aim of the present study to determine the main lesions that can occur in acute and chronic infections in intermediate hosts, when they ingest infective sporocysts that are shed in the opossum's feces, using budgerigars as a model. To this end, 12 budgerigars, Melopsittacus undulatus, were divided into two groups that received an inoculum with 60 and 120 sporocysts. Birds that died or were euthanized were necropsied, and the lung, tongue, liver, brain, heart, and skeletal striated muscles were collected and fixed in 10% formalin for histopathological analysis. The infectivity varied according to the sample and infective dose. Acute histopathological lesions were characterized by evidence of slightly degenerated hepatocyte cords that permeated the region of the blood vessel and hepatic sinusoids. Pulmonary tissue lesions were also observed in the parabronchial region with the presence of inflammatory infiltrates associated with areas of edema and atelectasis. In chronic infections, few mature cysts were observed in the chest, and many mature cysts in the thigh and tongue muscles. Thus, it was possible to conclude that lesions are highly characteristic in acute infection and, in chronic infections, cysts were present but without major lesions. In this case, the preferred organs of parasitism were the thigh and the tongue.

Sarcocystis gigantea infection associated with granulomatous eosinophilic myositis in a horse.

The only Sarcocystis species currently known to inhabit the fibers of skeletal and cardiac muscles in horses are S. fayeri, S. bertrami, and S. asinus. We describe herein the invasion of myofibers in a horse by S. gigantea, a sheep-specific species with low virulence in the original host. A hunter gelding was referred to a veterinary surgeon in Newmarket (UK). The anamnestic data reported that the horse had an initial history of swelling of the right forelimb with fluid on the front of the carpus and edema spreading up the forearm. Subsequently, 2 firm lumps were found on the left pectoral muscle adjacent to the axilla of the left forelimb. Histologic examination of biopsies from the lumps revealed multifocal granulomatous eosinophilic myositis associated with intact and degenerate encysted parasites, consistent with Sarcocystis spp. Based on amplification and DNA sequencing of the 18S rRNA gene obtained from formalin-fixed, paraffin-embedded tissue blocks, S. gigantea was identified. The presence of sarcocysts in equine skeletal muscles has been considered an incidental finding, and there are only sporadic associated reports of myositis. Our finding suggests that some Sarcocystis spp. have a wider intermediate host range than believed previously, and that Sarcocystis of other species (not considered horse-associated) can invade the muscle fibers of equids, leading to myositis.

Muscular Sarcocystosis in Sheep Associated With Lymphoplasmacytic Myositis and Expression of Major Histocompatibility Complex Class I and II.

Sarcocystosis is a protozoal disease affecting a wide range of animals. The aims of this study were to characterize the following in sheep: (1) the muscle pathology in Sarcocystis infection, (2) the inflammatory infiltrate and its relationship to severity of infection, and (3) immune markers expressed by parasitized muscle fibers and parasitic cysts. Skeletal muscle samples from 78 sheep slaughtered in southern Italy were snap frozen and analyzed by histopathology, immunohistochemistry, and immunofluorescence. Polymerase chain reaction (PCR) and sequencing were used for Sarcocystis species identification. All 40 muscle samples tested were PCR-positive for Sarcocystis tenella. Histologically, cysts were identified in 76/78 cases (97%), associated with an endomysial infiltrate of lymphocytes and plasma cells. The T cells were predominantly CD8+, with fewer CD4+ or CD79α+ cells. Eosinophils were absent. Notably, sarcolemmal immunopositivity for major histocompatibility complex (MHC) I and II was found in 76/78 cases (97%) and 75/78 cases (96%), respectively, both in samples with and in those without evident inflammatory infiltrate. The number of cysts was positively correlated with inflammation. In addition, MHC I was detected in 55/78 cyst walls (72%), and occasionally co-localized with the membrane-associated protein dystrophin. The findings suggest that muscle fibers respond to the presence of cysts by expression of MHC I and II. The possible role of MHC I and II in the inflammatory response and on the cyst wall is also discussed.

Histopathological Survey on Sarcocystis Species Infection in Slaughtered Cattle of Zabol-Iran

Objective: Sarcocystosis is an important zoonotic protozoal disease with worldwide distribution and wide range of hosts. The aim of the present study was to determine the intensity of Sarcocystis spp. infection and to show histopathological features of their cystic lesions in slaughtered cattle of Zabol- Iran. Methods: From April to September 2018, 500 tissue samples from esophagus, heart, diaphragm, tongue and masticatory muscles were prepared from 100 slaughtered cattle. All samples were fixed in 10% neutral buffered formalin and routine tissue processing protocol was performed. Results: The microscopic results showed that 92.2% of specimens had thin-walled cysts of S. cruzi and 14% had thick-walled Sarcocystis (S. hirsuta and S. hominis) but macrocyst was only observed in one cattle. The positivity rate of thin walled cysts was 58.8% for heart, 13.9% for masticatory muscles, 10.2% for tongue, 9.3% for esophagus and 7.8% for diaphragm. The positivity rate of thick walled cysts was 32.8% for esophagus, 28.6% for tongue, 22.9% for heart, 15.7% for masticatory muscles and 0% for diaphragm, which could represent either S. hominis or S. hirsuta. The most infected tissue was heart and the least infected tissue was diaphragm. Thin walled cysts (S. cruzi) were mostly found in heart and were less found in diaphragm. However, thick-walled cysts (S. hirsuta and S. hominis) were mostly detected in esophagus. No thick-walled cysts were found in diaphragm muscle. Conclusion: A high positivity rate of sarcocystosis in slaughtered cattle in Zabol abattoir revealed heavily environmental contamination of Sistan region by this important parasitic disease.

Serologic cross-reactivity between Sarcocystis neurona and Sarcocystis falcatula-like in experimentally infected Mongolian gerbils.

Sarcocystis neurona is the major cause of the equine protozoal myeloencephalitis (EPM) in the Americas and has opossums of the genus Didelphis as definitive hosts. Most isolates of Sarcocystis sp. shed by opossums in Brazil differ genetically from the known species of Sarcocystis. These Brazilian isolates behave similarly as Sarcocystis falcatula, which causes sarcocystosis in birds, and for this reason, have been classified as Sarcocystis falcatula-like. Genes coding for the immunodominant surface antigens SAG2, SAG3 and SAG4 of S. falcatula-like are similar to those from S. neurona. It is unknown the Sarcocystis species that causes EPM in Brazil, as S. neurona has never been genetically confirmed in Brazilian horses. All cases associated with EPM in Brazil were diagnosed by immunological tests, which are not specific for S. neurona infection. It is possible that S. falcatula-like may infect horses in Brazil. The aims of the current study were to test the susceptibility of gerbils (Meriones unguiculatus) to experimental infections with S. neurona and S. falcatula-like, and to investigate potential serologic cross-reactivity to these parasites by immunofluorescent antibody test (IFAT) and Western blot (WB). A total of 27 gerbils, distributed in five experimental groups (G1-G5), were employed in this work (G1: 4 negative controls; G2: 6 infected with S. neurona merozoites, G3: 6 infected with S. falcatula-like merozoites; G4 and G5 (5 and 6, respectively, infected with different doses of sporocysts). None of the 17 animals that seroconverted for the parasites in IFAT presented any visualized organism or Sarcocystis DNA in the examined tissues. No serologic cross-reactivity was observed using IFAT. However, sera from animals infected with S. falcatula-like and S. neurona presented the same pattern of antigenic recognition when S. neurona merozoites were used as antigen in WB, including reactivity to proteins of 30 and 16 kDa, regarded as specific markers for S. neurona-infected animals. Gerbils did not sustain infection by these parasites, although produced antibodies after inoculation. These results are suggestive that other animal species that are exposed to S. falcatula-like, including horses, may present serologic cross-reactivity to S. neurona in WB. IFAT was demonstrated to be more specific that WB for the detection of antibodies to S. falcatula-like and S. neurona in the experimental conditions of this study.

Polyphasic Rhabdomyositis in California Sea Lions (Zalophus Californianus): Pathology and Potential Causes.

A myositis syndrome has been recognized for more than a decade in California sea lions (CSLs; Zalophus californianus) but a detailed description of the lesions and potential causes of this condition is lacking. The tissues of 136 stranded CSLs with rhabdomyositis were examined. Rhabdomyositis was considered incidental in 67% (91/136) of the CSLs, and a factor contributing to the animal stranding (significant rhabdomyositis) in 33% (45/136). Of the 91 cases with incidental rhabdomyositis, lesions consisted of a few small foci of lymphohistiocytic inflammation. Of the 45 cases with significant rhabdomyositis, 28 (62%) also presented with major comorbidities such as leptospirosis (2 animals) and domoic acid toxicosis (6 animals), whereas 17 (38%) had severe polyphasic rhabdomyositis as the only major disease process associated with mortality. In these animals, most striated muscles had multiple white streaks and diffuse atrophy. Microscopically, there was myofiber necrosis surrounded by lymphocytes and histiocytes admixed with areas of myofiber regeneration, and/or moderate to severe rhabdomyocyte atrophy usually adjacent to intact Sarcocystis neurona cysts. At the interface of affected and normal muscle, occasional T lymphocytes infiltrated the sarcoplasm of intact myocytes, and occasional myofibers expressed MHCII proteins in the sarcoplasm. S. neurona antibody titers and cyst burden were higher in animals with significant polymyositis antibody titers of (26125 ± 2164, 4.5 ± 1.2 cysts per section) and active myonecrosis than animals with incidental rhabdomyositis antibody titers of (7612 ± 1042, 1.7 ± 0.82 cysts per section). The presented findings suggest that S. neurona infection and immune-mediated mechanisms could be associated with significant polyphasic rhabdomyositis in CSLs.

Confirmation of Sarcocystis jamaicensis Sarcocysts in IFN-γ Gene Knockout Mice Orally Inoculated with Sporocysts from a Red-Tailed Hawk ( Buteo jamaicensis).

Here, we report confirmation of sarcocysts of Sarcocystis jamaicensis in an experimental intermediate host, IFN-γ gene knockout (KO) mice orally inoculated sporocysts from its natural definitive host, a red-tailed hawk ( Buteo jamaicensis) (RTH). A RTH submitted to the Carolina Raptor Center, Huntersville, North Carolina, was euthanized because it could not be rehabilitated and released. Fully sporulated sporocysts from intestinal scrapings of the RTH were orally fed to 2 laboratory-reared outbred Swiss Webster mice (SW; Mus musculus) and to 2 KO mice. The sporocysts were infective for KO mice but not to SW mice. Both SW mice remained asymptomatic, and neither schizonts nor sarcocysts were found in their tissues when euthanized on day 54 post-inoculation (PI). The KO mice developed neurological signs and were necropsied 38-54 days PI. Schizonts/merozoites were found in both KO mice euthanized and they were confined to the brain. The predominant lesion was meningoencephalitis. Microscopic sarcocysts were found in muscles of both KO mice. When viewed with light microscopy, the sarcocyst wall appeared thin (<1 µm thick) and smooth. Ultrastructural details of sarcocysts are described.

Sarcocystis calchasi Outbreak in Feral Rock Pigeons ( Columba livia) in California.

Twenty-two feral rock pigeons ( Columba livia) from 10 counties in California with ataxia, torticollis, and difficulty standing and flying were admitted to rehabilitation centers in late winter and spring of 2017 and died or were euthanized. Common necropsy findings included thin body condition, generalized deep red discoloration of organs, and hemorrhagic subcutaneous neck tissues. Meningoencephalitis was observed microscopically in 16 pigeons, and 3 also had protozoal schizonts in the brain. The most consistently affected regions of the brain were cerebellum and brainstem. Skeletal muscles, and less frequently the heart, contained large intrasarcoplasmic bradyzoites typically without inflammation. Fifteen of the 22 birds tested positive using pan- Sarcocystis polymerase chain reaction. The sequence of the amplicon was most closely related to S. calchasi, and the 8 subtyped sequences had 100% homology with S. calchasi. This investigation demonstrated the transcontinental and North American spread of S. calchasi causing a disease outbreak in free-ranging rock pigeons, thus warranting increased surveillance in susceptible native columbids.

Molecularly Confirmed Acute, Fatal Sarcocystis falcatula Infection in the Rainbow Lorikeets ( Trichoglossus moluccanus) at the Philadelphia Zoo.

The protozoan parasite Sarcocystis falcatula is an important cause of clinical disease in several avian intermediate hosts. The host range of S. falcatula is wide, and numerous outbreaks of acute sarcocystosis have been reported in passerine and psittacine birds in captivity in the Americas. Previous diagnosis was performed by serologic methods, light, and/or electron microscopic examinations with limited molecular confirmation. Here, we report histological and molecular diagnosis of acute, fatal S. falcatula infections in rainbow lorikeets ( Trichoglossus moluccanus) at the Philadelphia Zoo. Pulmonary sarcocystosis was suspected antemortem in 3 lorikeets (3-5 yr old); these birds died despite antiprotozoal therapy. The predominant lesion was pneumonia associated with S. falcatula-like schizonts in pulmonary vascular endothelium. The multilocus PCR-DNA sequencing ( 18S rDNA, 28S rDNA, ITS-1, and cox1) of frozen lung tissue confirmed S. falcatula infections in all 3 birds. Our results and previous studies suggest that acute pulmonary form of sarcocystosis is a major contributor of death to Old World psittacine birds.

Histopathological, morphological, and molecular characterization of Sarcocystis species in elk (Cervus elaphus) from Pennsylvania, USA.

Sarcocystis sarcocysts are common in many species of domestic and wild animals. Here, we report sarcocystosis in muscles from 91 free range elk (Cervus elaphus) from Pennsylvania, USA, tested by histopathology, transmission electron microscopy (TEM), and DNA sequencing. Sarcocysts were detected in hematoxylin and eosin (HE)-stained sections from 83 of 91 (91.2%) elk, including 83/91 (91.2%) tongues and 15/17 (88.2%) hearts. With respect to age, sarcocysts were found in 0/5 calves, 8/9 (88.8%) yearlings, and 75/77 (97.4%) adults. Sarcocysts were identified in 62/69 (89.4%) females and 21/22 (91.2%) males. Associated lesions were mild and consisted of inflammatory foci around degenerate sarcocysts. There were two morphologically distinct sarcocysts based on wall thickness, thin (< 0.5 µm) and thick-walled (> 4.0 µm). Thin-walled sarcocysts had a TEM "type 2" and villar protrusions (vps), identical to Sarcocystis wapiti previously described from elk in western USA. This species was present both in tongue and heart samples and was detected in all infected elk. Thick-walled sarcocysts consisted of three morphologic variants, referred to herein as subkinds A, B, C. Subkind A sarcocysts were rare; only four sarcocysts were found in three elk. Histologically, they had a 5-8-µm thick wall with tufted vp. By TEM, the sarcocyst wall was "type 12" and appeared similar to Sarcocystis sybillensis, previously described from elk in USA. Subkind B, Sarcocystis sp.1 sarcocysts were also rare, found in only 1 elk. These sarcocysts had 6.7-7.3-µm-thick wall with TEM "type 15b" vp. Subkind C Sarcocystis sp.2 sarcocysts were more common (22/91). Morphologically, the sarcocyst wall was 6.1-6.8 µm thick and contained "type 10b" vp. Comparisons of ribosomal DNA loci with published sequences indicated all sarcocysts were similar to what has previously been isolated from cervid hosts across the northern hemisphere. Phylogenetic analysis placed the thin-walled S. wapiti within a strongly supported clade with S. linearis and S. taeniata, while the thick-walled cysts were very closely related to S. truncata, S. elongata, S. silva, and S. tarandi. Further sequencing is needed to produce molecular diagnostics to distinguish among these species. North American elk are hosts to multiple Sarcocystis species with diverse morphology, deriving from two separate evolutionary lineages.

Molecular Identification of Sarcocystis grueneri in Wild Korean Water Deer (Hydropotes inermis argyropus).

The cysts of Sarcocystis grueneri were detected and characterized from the cardiac muscles of the Korean water deer (Hydropotes inermis argyropus). Of the 38 heart muscle samples examined by light microscopy, 10 were found infected with the cysts of Sarcocystis sp. The cysts appeared oval to spherical shape and measured 110-380 µm in length and 90-170 µm in width. A phylogenetic tree of the 18S rRNA sequences (1.5 kb) revealed a close relationship of the infected cysts to genus Sarcocystis. The 18S rRNA sequence of the infected cysts showed 100% identity to S. grueneri and 97% to S. capracanis. Here, we first report the S. grueneri infections in the Korean water deer.

Oxidative stress and hepatic injury induced in mice fed a Sarcocystis hirsuta cyst extract.

We studied the toxic effects of a Sarcocystis hirsuta cyst extract fed to mice. Degenerative changes were found in mice gavage-fed fresh, frozen, and heat-treated S. hirsuta cyst extract. There were increases in the levels of serum aspartate aminotransferase and alanine aminotransferase as well as hepatic and brain malondialdehyde (MDA) levels along with concomitant decreases in catalase (CAT) and superoxide dismutase (SOD) activities of mice receiving fresh and frozen S. hirsuta extracts. Gavage feeding of heat-treated S. hirsuta cyst extract had no effects on liver enzymes or brain MDA content, but the liver MDA level did increase. Mice in the heat-treated cyst group showed reduced CAT and SOD activities as well as increased hepatic MDA levels compared to those in the control group. These results indicate that an extract of S. hirsuta cyst can induce oxidative stress and hepatic injury, even after heat treatment.

Histologic characterization of eosinophilic encephalitis in horses in Florida.

Eosinophils within the central nervous system are abnormal and are usually associated with fungal or parasitic infections in horses. Causative agents include Halicephalobus gingivalis, Sarcocystis neurona, and Neospora hughesi. Confirmation of these organisms via specific testing is typically not performed, and final diagnoses are often presumptive. With molecular technology, many of these organisms can now be confirmed. This is important for emerging and zoonotic pathogens, including Angiostrongylus cantonensis, an emerging parasite of interest in the southeastern United States. We retrospectively analyzed eosinophilic encephalitides in Floridian horses for H. gingivalis, S. neurona, and A. cantonensis, applied descriptors to equine eosinophilic encephalitides, and determined if a relationship existed between these descriptions and specific etiologic agents. In a database search for horses with eosinophilic and other encephalitides submitted to the University of Florida, College of Veterinary Medicine, Anatomic Pathology Service, we identified 27 horses with encephalitis, and performed DNA isolation and rtPCR on formalin-fixed, paraffin-embedded blocks from these cases. Real-time PCR identified 6 horses positive for S. neurona and 4 horses positive for H. gingivalis; all horses were negative for A. cantonensis. All 25 control horses were negative for H. gingivalis, S. neurona, and A. cantonensis. Pattern analysis and eosinophil enumeration were not useful in differentiating among causes of eosinophilic encephalitides in horses in our study.

INVESTIGATIONS INTO CAUSES OF NEUROLOGIC SIGNS AND MORTALITY AND THE FIRST IDENTIFICATION OF SARCOCYSTIS CALCHASI IN FREE-RANGING WOODPECKERS IN GERMANY.

Between June and November 2015, 25 woodpeckers (Picidae) with neurologic signs or unknown cause of death were admitted to a veterinary clinic. Alive birds were clinically examined. Birds that were found dead or died despite intensive care treatment were forwarded to a pathologic examination. Necropsy and subsequent tests included screening for several infectious agents and toxins. Three birds tested positive for Sarcocystis calchasi. Toxoplasma gondii was detected in one bird demonstrating intracerebral cysts. Mycoplasma gypis was detected in one woodpecker in the absence of respiratory signs. Several microbial pathogens (eg, Aspergillus fumigatus, Clostridium perfringens, and Escherichia coli) were isolated from single individuals. However, there was no consistent finding in all birds that could explain nervous signs and mortality of the woodpeckers examined. To the authors' knowledge, M. gypis and S. calchasi were detected in a woodpecker for the first time in this study.

Atypical fatal sarcocystosis associated with Sarcocystis neurona in a White-nosed coati (Nasua narica molaris).

The protozoan parasite Sarcocystis neurona is an important cause of disease in horses (equine protozoal myeloencephalitis, EPM) and marine mammals. Isolated reports of clinical EPM-like disease have been documented in a zebra, raccoon, domestic cat, domestic dog, ferret, skunk, mink, lynx, red panda and fisher. The predominant disease is encephalomyelitis associated with schizonts in neural tissues. Here, we report highly disseminated sarcocystosis, in many tissues of a captive White-nosed coati (Nasua narica molaris). The 14year old, neutered male coati was euthanized due to progressive weakness, lethargy, and inappetence. Schizonts, including free and intracellular merozoites were detected in many cell types, and differed morphologically from S. neurona schizonts in horses. Only a few sarcocysts were seen in skeletal muscle and the myocardium. Immunohistochemically, the protozoa reacted positively to S. neurona but not to Toxoplasma gondii antibodies. Severe inflammtory disease detected in the stomach, intestine, adrenal and thyroid glands, ciliary body of eye, and urinary bladder associated with schizonts in the coati has not been reported earlier in any host with EPM. Although, a few schizonts were found in the brain, encephalitis was minimal and not the cause of clinical signs. Multilocus PCR-DNA sequencing using DNA derived from the coati lung tissue identified an S. neurona infection using the 18S, 28S and ITS-1 markers, and a novel genotype using primer pairs against antigenic surface proteins (SnSAG3, SnSAG4, SnSAG1-5-6) and microsatellite markers (MS, SN7, SN9). Although the genotype was similar to the widely distributed Type VI strain, it possessed a novel allele at SnSAG5, and a different MS combination of repeats at SN7 and SN9. Whether this severe parasitism was related to the host or the parasite needs further investigation.

Small sarcocysts can be a feature of experimental infections with Sarcocystis neurona merozoites.

Several reports indicate the presence of small tissue cysts associated with Sarcocystis neurona infections. Several failed attempts to develop tissue cysts in potential intermediate host using in vitro derived parasites originally isolated from horses with equine protozoal myeloencephalitis suggest that the experimental methods to achieve bradyzoites with those isolates was not possible. Those prior studies reported the lack of detectable sarcocysts based on histology and in vivo feeding trials. A recent report of successful production and detection of small sarcocysts triggered us to review archived tissues from earlier experimental infection studies. The retrospective review sought to determine if small sized sarcocysts were not detected due to their relatively smaller size and infrequency as compared to larger sized sarcocysts produced with other isolates in these experimental inoculation trials. Tissues from two prior in vivo inoculation studies, involving in vitro-produced parasites inoculated into laboratory-reared cats and raccoons, were re-examined by immunohistochemistry staining to more easily detect the tissue cysts. In the experimental cat study no small tissue cysts were seen, consistent with the original publication results. However, in the experimental raccoon study, one raccoon inoculated with an EPM-derived isolate, SN-UCD1, had small sarcocysts not reported in the original publication. This retrospective study suggests that much closer scrutiny of tissues, including the use of immunohistochemistry on tissue sections is required to detect the smaller S. neurona sarcocysts associated with the experimental inoculations of the isolates originally derived from horses with EPM.

Parasitemia due to Sarcocystis neurona-like infection in a clinically ill domestic cat.

An 8-year-old, 6-kg, male neutered Domestic Shorthair cat was presented to The Ohio State University Veterinary Medical Center (OSU-VMC) for difficulty breathing. Physical examination and thoracic radiographs indicated pneumonia, a soft-tissue mass in the left caudal lung lobe, and diffuse pleural effusion. The effusion was classified as modified transudate. Rare extracellular elongated (~5-7 µm × 1-2 µm) zoites with a central round to oval-shaped purple to deep purple vesicular nucleus with coarsely stippled chromatin and light blue cytoplasm were seen on a peripheral blood smear. Serum IgG and IgM were positive for Sarcocystis sp. antibodies and negative for Toxoplasma gondii antibodies, suggesting that the infection was acute rather than a recrudescence of prior infection. This organism was most consistent with either Sarcocystis neurona or Sarcocystis dasypi based on DNA sequence analysis of PCR products using COC ssRNA, ITS-1, snSAG2, and JNB25/JD396 primer sets. This is the first report to visualize by light microscopy circulating Sarcocystis sp. merozoites in the peripheral blood of a domestic cat. Therefore, Sarcocystis should be considered as a differential diagnosis in cats with suspected systemic protozoal infection.

Muscular sarcocystosis: an index case in a native Malaysian.

A previously healthy 20-year-old man presented with prolonged intermittent low grade fever and cough for 6months. He had bilateral calf pain and lower limb weakness 2days prior to admission. Physical examination revealed multiple enlarged lymph nodes with hepatomegaly. There was bilateral calf tenderness with evidence of proximal myopathy. Full blood picture showed lymphocytosis with reactive lymphocytes and eosinophilia. Creatine kinase and lactate dehydrogenase were markedly elevated. Over 2 weeks of admission, patient was treated symptomatically until the muscle biopsy of right calf revealed eosinophilic myositis with muscular sarcocystosis. He was treated with albendazole and high-dose corticosteroids. Symptoms subsided on reviewed at 2weeks and the dose of corticosteroid was tapered down slowly over a month. Due to poor compliance, he was readmitted 1month later because of relapsed. High-dose corticosteroid was restarted and duration for albendazole was prolonged for 1month. His symptom finally resolved over 2weeks.