Epizootiology of Sarcocystis infections in mule deer fawns in Oregon

From 1974 to 1977, 62 wild mule deer (Odocoileus hemionus) fawns from Steens Mountain, Ore were euthanatized in autumn (23 deer), winter (21 deer), and spring (18 deer). The number of sarcocysts of Sarcocystis spp was counted in histologic sections of various muscular organs. Sarcocysts were seen in the muscle specimens of 14 of the 23 deer euthanatized in autumn (September to November) and in specimens from all 39 deer euthanatized in winter (December and January) and spring (March and April). The sarcocyst burden was greatest in the spring (736/deer), less in the winter (150/deer), and least in autumn (12/deer). Most sarcocysts collected from 3- to 5-month-old deer in autumn were immature, whereas most sarcocysts collected from 9- and 10-month-old deer in the spring were mature. More sarcocysts were seen in sections of muscles from limbs than in those of tongue, esophagus, and other skeletal muscles; the fewest sarcocysts were seen in the heart. Degenerating sarcocysts were seen in deer examined in the spring, but not in deer examined in autumn and winter. Sarcocystis was the only infectious agent found in unthrifty deer fawns. Of the 18 fawns (6 in autumn, 1974; 6 in winter, 1974; and 6 in spring, 1975) examined for helminths, only mild infections were seen in the deer examined in the spring of 1975. From 1974 to 1977, from the Crooked Creek area of Oregon, 48 mule deer fawns (12 in autumn, 18 in winter, and 18 in spring) were euthanatized and evaluated for Sarcocystis infections.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sarcocystis infection in the white-tailed deer (Odocoileus virginianus) in Montana: intensity and description of Sarcocystis odoi n sp

Sarcocystis infection was diagnosed in 27 of 36 (75%) samples of meat from white-tailed deer (Odocoileus virginianus) in Montana. Two structurally distinct thin- and thick-walled sarcocysts were found in the white-tailed deer; the thin-walled sarcocysts were those of S odocoileocanis. A new name, S odoi, was proposed for the thick-walled sarcocysts. Sarcocysts of S odoi were up to 1,050 microns long and 260 microns wide and contained a 6.5- to 12-microns thick wall. The ultrastructure of sarcocysts of S odocoileocanis was compared with that of S odoi. A cat fed meat containing thin- and thick-walled sarcocysts shed oocysts and sporocysts 24 days later. The sporocysts in the cat's feces were 13.3 X 9.6 microns and probably belonged to S odoi.     

Sarcocystis infections in mule deer (Odocoileus hemionus) in Montana and the descriptions of three new species

Four structural types of sarcocysts of Sarcocystis were found in skeletal muscles of mule deer in Montana. Type I sarcocysts were thin walled (1 to 3 micron) and belonged to S hemionilatrantis. Types II to IV sarcocysts were thick walled (2 to 10 microns) and new names were proposed for them. Type II sarcocysts with long villar projections were named S hemioni. Type III sarcocysts with club-shaped villi of uneven thickness were named S youngi. Type IV sarcocysts with walls of uneven thickness and containing hair-like protrusions were named S americana.     

Lymphoproliferation in captive wild ruminants affected with malignant catarrhal fever: 25 cases (1977-1985)

The severity of lymphoproliferative disease associated with malignant catarrhal fever was extremely variable among 25 animals at the San Diego Wild Animal Park. Severe lymphoproliferative disease was seen in 3 of 10 Formosan Sika deer (Cervus nippon taiouanus), 3 of 6 Indian Axis deer (Cervus a axis), 3 of 6 Barasingha deer (Cervus d duvauceli), and 1 of 3 Nilgai (Boselaphus tragocamelus). Two Sika deer and 2 Barasingha deer had lesions morphologically indistinguishable from lymphosarcoma. Our findings were consistent with the hypothesis that alcelaphine herpesvirus-1 has oncogenic potential.     

Prevalence of Sarcocystis species in sheep and goats in northern Nigeria.

Tissue samples comprising the oesophagus and diaphragm were collected from 400 sheep and 400 goats slaughtered at the abattoirs in the study area. Out of this number, 36 were positive for Sarcocystis cysts (sarcocysts) in sheep and 56 in goats. The sarcocysts in sheep measured 35.7 to 500 microns lengthwise and the cyst-wall 2.4 microns. They were identified to be Sarcocystis tenella. The cysts in goats measured 98 to 700 microns and the cyst-wall 2.7 microns. They were identified to be Sarcocystis capracanis. In both animals species, the sarcocysts were more frequent in the oesophagus than in the diaphragm. All sarcocysts seen were microscopic.     

Prevalence of Sarcocystis sarcocysts in nine-banded armadillos (Dasypus novemcinctus) from Florida.

The prevalence and identity of Sarcocystis spp. sarcocysts in the skeletal muscles of nine-banded armadillos (Dasypus novemcinctus) collected from Alachua County, FL, were determined. H & E stained sections of skeletal muscle from tongue and thigh were examined. Thirty nine of 63 (61.9%) armadillos examined contained Sarcocystis sarcocysts. Two species were identified, Sarcocystis dasypi and Sarcocystis diminuta. Sarcocystis dasypi sarcocysts were found in 38 of 63 (60.3%) and S. diminuta sarcocysts were found in 6 of 63 (9.5%). Sarcocysts of S. dasypi were larger, more densely packed with bradyzoites, and bradyzoites contained within the sarcocyst were smaller than those of S. diminuta. Mixed infections occurred in 5 of 63 (7.9%) armadillos examined.     

Association of eosinophilic myositis with an unusual species of Sarcocystis in a beef cow.

The carcass of a mature cow had numerous, disseminated lesions typical of eosinophilic myositis. To elucidate the nature and possible cause of the lesions, histological sections were examined by light microscopy and selected areas were removed and processed for electron microscopy. The lesions were granulomatous in nature. Each granuloma contained at its centre an intact or ruptured sarcocyst associated with degenerate muscle fibers. Surrounding this was a layer of epithelioid cells and an intense accumulation of inflammatory cells, most of which were eosinophils. The primary cyst wall of the sarcocysts in these granulomas consisted of hair-like protrusions that featured many unusual electron-dense bodies. Sarcocysts with ultrastructures characteristic of Sarcocystis cruzi and Sarcocystis hirsuta were also present in muscle from the same animal, but these sarcocysts lacked any associated cellular responses. The eosinophilic myositis in this case appeared to be associated with sarcocystosis of an unknown species. Possibly, the inflammatory reaction was due to the host-parasite interaction in an unusual host.     

Prevalence of sarcocysts of Sarcocystis capracanis in oesophagus and tail muscles of naturally infected goats

The prevalence of sarcocysts of Sarcocystis capracanis in oesophagus and tail muscles of 76 goats slaughtered at Jabalpur, India, was found to be 67.10 and 46.05%, respectively. A total of 79.3% of oesophagi and 72.4% of tails had sarcocysts in older goats (greater than 1 year), but their prevalence in younger animals (less than 1 year) was 40.0% in oesophagi and none in tails. Therefore examination by biopsy of the tail muscles can be used to monitor the development of Sarcocystis sarcocysts in experimental infection without killing the animal.     

Morphological and molecular identification of three species of Sarcocystis in reindeer (Rangifer tarandus tarandus) in Iceland

Six Sarcocystis species have previously been described from reindeer in Norway based on sarcocyst morphology and DNA sequencing. The aim of this study was to determine whether reindeer in Iceland, which descend from reindeer imported from Norway in 1787, also were infected with Sarcocystis, and to identify and genetically characterise any species present. Muscle tissue from the heart, diaphragm and/or oesophagus was collected from 36 reindeer in Iceland. Pieces of all tissue samples were examined histologically. Frozen/thawed samples of cardiac muscle, oesophagus and/or diaphragm from 11 of the 36 reindeer were also examined under a stereoscopic microscope and sarcocysts present were identified to species either in situ or under a light microscope. Two cysts of each species, originating from two different reindeer were randomly selected for DNA analyses. The complete ssu rRNA gene was amplified by the polymerase chain reaction (PCR) and sequenced. In addition, two sarcocysts that could not be classified by microscopic examination were selected for partial ssu rRNA gene sequence analysis. By histology, sarcocysts were found in the diaphragm and/or oesophagus of 8 of 36 (22.2%) animals. By examination of fresh tissue, sarcocysts of Sarcocystis rangi, S. tarandivulpes and S. hardangeri were found in the oesophagus of seven of nine (77.8%) animals, suggesting a high prevalence of Sarcocystis in the Icelandic reindeer population. Cyst morphology and the ssu rRNA gene sequence of each of the three species were identical to isolates of the same species from Norwegian reindeer. DNA sequencing was useful in order to identify cysts with an ambiguous morphology. This is the first record of these Sarcocystis species in reindeer outside Norway.     

Ultrastructure of sarcocysts from water buffalo in India

The ultrastructure of sarcocysts of macro- and microscopic species of Sarcocystis was compared from naturally infected water buffalo from India. Grossly visible sarcocysts had walls consisting of cauliflower-like villar protrusions, typical of S. fusiformis. The sarcocyst wall of the microscopic species of Sarcocystis was 6.4 microns thick and consisted of tightly packed conical villar protrusions that were 9.6 microns long and 3.7 microns wide at the base. At approximately 3 microns above the base, the distal two-thirds of the villar protrusion became conical shaped and was bent laterally at an angle of 45 degrees to the sarcocyst surface. The granular layer beneath the villar protrusions was 0.9 microns thick. In S. levinei the granular layer was 1.9 microns thick, the villar protrusions were narrow and it had a highly undulating primary cyst wall. Whether the microscopic S. levinei-like sarcocysts of Indian and Malaysian water buffalo are distinct species of Sarcocystis will require further investigation.     

IS SARCOCYSTIS TENELLA TWO SPECIES?

When mutton containing microscopic sarcocysts of Sarcocystis spp was fed to dogs and cats, only dogs excreted sporocysts in their faeces. Conversely, mutton containing macroscopic sarcocysts produced infection in cats but not dogs. Sheep were experimentally infected with sporocysts from the faeces of dogs and cats either separately or together, and reciprocal feeding trials with their meat carried out with dogs and cats. The results of the experiments strongly suggest that Sarcocystis tenella of sheep may be 2 distinct species, one with the cat as definitive host, and the other parasitising the dog.     

Prevalence of dog-derived Sarcocystis spp. in some New Zealand lambs

Pepsin: hydrochloric acid digestion and histological examination of the myocardium of 51 hearts from five to nine month-old lambs from the southern half of the North Island, showed that 47 (92%) were infected with microscopic sarcocysts that are presumed to be dog-derived. Of 157 sarcocysts detected histologically, 32 corresponded morphologically with Sarcocystis ovicanis and 120 with Sarcocystis tenella (Syn. S. arieticanis). The remainder could not be identified as to type.     

Evidence to support horses as natural intermediate hosts for Sarcocystis neurona

Opossums (Didelphis spp.) are the definitive host for the protozoan parasite Sarcocystis neurona, the causative agent of equine protozoal myeloencephalitis (EPM). Opossums shed sporocysts in feces that can be ingested by true intermediate hosts (cats, raccoons, skunks, armadillos and sea otters). Horses acquire the parasite by ingestion of feed or water contaminated by opossum feces. However, horses have been classified as aberrant intermediate hosts because the terminal asexual sarcocyst stage that is required for transmission to the definitive host has not been found in their tissues despite extensive efforts to search for them [Dubey, J.P., Lindsay, D.S., Saville, W.J., Reed, S.M., Granstrom, D.E., Speer, C.A., 2001b. A review of Sarcocystis neurona and equine protozoal myeloencephalitis (EPM). Vet. Parasitol. 95, 89-131]. In a 4-month-old filly with neurological disease consistent with EPM, we demonstrate schizonts in the brain and spinal cord and mature sarcocysts in the tongue and skeletal muscle, both with genetic and morphological characteristics of S. neurona. The histological and electron microscopic morphology of the schizonts and sarcocysts were identical to published features of S. neurona [Stanek, J.F., Dubey, J.P., Oglesbee, M.J., Reed, S.M., Lindsay, D.S., Capitini, L.A., Njoku, C.J., Vittitow, K.L., Saville, W.J., 2002. Life cycle of Sarcocystis neurona in its natural intermediate host, the raccoon, Procyon lotor. J. Parasitol. 88, 1151-1158]. DNA from schizonts and sarcocysts from this horse produced Sarcocystis specific 334bp PCR products [Tanhauser, S.M., Yowell, C.A., Cutler, T.J., Greiner, E.C., MacKay, R.J., Dame, J.B., 1999. Multiple DNA markers differentiate Sarcocystis neurona and Sarcocystis falcatula. J. Parasitol. 85, 221-228]. Restriction fragment length polymorphism (RFLP) analysis of these PCR products showed banding patterns characteristic of S. neurona. Sequencing, alignment and comparison of both schizont and sarcocyst DNA amplicons showed 100% identity. Although Koch's postulates have not been demonstrated in this case study, the finding of mature, intact S. neurona schizonts and sarcocysts in the tissues of this single horse strongly suggests that horses have the potential to act as intermediate hosts. Further studies are needed to demonstrate Koch's postulates with repeated transfer of S. neurona between opossums and horses.     

Brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona and act as intermediate hosts

We tested the hypothesis that brown-headed cowbirds (Molothrus ater) harbor Sarcocystis neurona, the agent of equine protozoal myeloencephalitis (EPM), and act as intermediate hosts for this parasite. In summer 1999, wild caught brown-headed cowbirds were collected and necropsied to determine infection rate with Sarcocystis spp. by macroscopic inspection. Seven of 381 (1.8%) birds had grossly visible sarcocysts in leg muscles with none in breast muscles. Histopathology revealed two classes of sarcocysts in leg muscles, thin-walled and thick-walled suggesting two species. Electron microscopy showed that thick-walled cysts had characteristics of S. falcatula and thin-walled cysts had characteristics of S. neurona. Thereafter, several experiments were conducted to confirm that cowbirds had viable S. neurona that could be transmitted to an intermediate host and cause disease. Specific-pathogen-free opossums fed cowbird leg muscle that was enriched for muscle either with or without visible sarcocysts all shed high numbers of sporocysts by 4 weeks after infection, while the control opossum fed cowbird breast muscle was negative. These sporocysts were apparently of two size classes, 11.4+/-0.7 microm by 7.6+/-0.4 microm (n=25) and 12.6+/-0.6 microm by 8.0+/-0 microm (n=25). When these sporocysts were excysted and introduced into equine dermal cell tissue culture, schizogony occurred, most merozoites survived and replicated long term and merozoites sampled from the cultures with long-term growth were indistinguishable from known S. neurona isolates. A cowbird Sarcocystis isolate, Michigan Cowbird 1 (MICB1), derived from thin-walled sarcocysts from cowbirds that was passaged in SPF opossums and tissue culture went on to produce neurological disease in IFNgamma knockout mice indistinguishable from that of the positive control inoculated with S. neurona. This, together with the knowledge that S. falcatula does not cause lesions in IFNgamma knockout mice, showed that cowbird leg muscles had a Sarcocystis that fulfills the first aim of Koch's postulates to produce disease similar to S. neurona. Two molecular assays provided further support that both S. neurona and S. falcatula were present in cowbird leg muscles. In a blinded study, PCR-RFLP of RAPD-derived DNA designed to discriminate between S. neurona and S. falcatula showed that fresh sporocysts from the opossum feeding trial had both Sarcocystis species. Visible, thick-walled sarcocysts from cowbird leg muscle were positive for S. falcatula but not S. neurona; thin-walled sarcocysts typed as S. neurona. In 1999, DNA was extracted from leg muscles of 100 wild caught cowbirds and subjected to a PCR targeting an S. neurona specific sequence of the small subunit ribosomal RNA (SSU rRNA) gene. In control spiking experiments, this assay detected DNA from 10 S. neurona merozoites in 0.5g of muscle. In the 1999 experiment, 23 of 79 (29.1%) individual cowbird leg muscle samples were positive by this S. neurona-specific PCR. Finally, in June of 2000, 265 cowbird leg muscle samples were tested by histopathology for the presence of thick- and thin-walled sarcocysts. Seven percent (18/265) had only thick-walled sarcocysts, 0.8% (2/265) had only thin-walled sarcocysts and 1.9% (5/265) had both. The other half of these leg muscles when tested by PCR-RFLP of RAPD-derived DNA and SSU rRNA PCR showed a good correlation with histopathological results and the two molecular typing methods concurred; 9.8% (26/265) of cowbirds had sarcocysts in muscle, 7.9% (21/265) had S. falcatula sarcocysts, 1.1% (3/265) had S. neurona sarcocysts, and 0.8% (2/265) had both. These results show that some cowbirds have S. neurona as well as S. falcatula in their leg muscles and can act as intermediate hosts for both parasites.     

The fox as definitive host for Sarcocystis sp. Gjerde, 1984 from skeletal muscle of reindeer (Rangifer tarandus). With a proposal for Sarcocystis tarandivulpes n. sp. as replacement name

Skeletal muscle of 5 wild reindeer was examined for sarcocysts and used for experimental infection of 6 foxes. Skeletal and cardiac muscle of another reindeer were only examined for sarcocysts. The skeletal muscle of all animals was infected with Sarcocystis sp.. In 2 of the animals cysts of S. hardangeri were also present. The single heart examined contained only cysts of S. grueneri.Four foxes given skeletal muscle containing apparently only cysts of Sarcocystis sp., started shedding Sarcocystis sporocysts, measuring on average 13.6×9.8 µm, after a prepatent period of 10–12 days. Two foxes given skeletal muscle containing cysts of both Sarcocystis sp. and S. hardangeri shed similar sporocysts, measuring on average 13.5×9.7 µm, after a prepatent period of 10–12 days.Based on the results from the present and previous investigations, Sarcocystis sp. is considered to have foxes (Vulpes vulpes and Alopex lagopus) and dogs (Ganis familiaris) as definitive hosts, becoming the second species of Sarcocystis with a known reindeer/Canidae life cycle. The name Sarcocystis tarandivulpes n. sp. is proposed as a replacement name for Sarcocystis sp. Gjerde, 1984 from skeletal muscle of reindeer.     

Experimental inoculation of domestic cats (Felis domesticus) with Sarcocystis neurona or S. neurona-like merozoites

Sarcocystis neurona is the parasite most commonly associated with equine protozoal myeloencephalitis (EPM). Recently, cats (Felis domesticus) have been demonstrated to be an experimental intermediate host in the life cycle of S. neurona. This study was performed to determine if cats experimentally inoculated with culture-derived S. neurona merozoites develop tissue sarcocysts infectious to opossums (Didelphis virginiana), the definitive host of S. neurona. Four cats were inoculated with S. neurona or S. neurona-like merozoites and all developed antibodies reacting to S. neurona merozoite antigens, but tissue sarcocysts were detected in only two cats. Muscle tissues from the experimentally inoculated cats with and without detectable sarcocysts were fed to laboratory-reared opossums. Sporocysts were detected in gastrointestinal (GI) scrapings of one opossum fed experimentally infected feline tissues. The study results suggest that cats can develop tissue cysts following inoculation with culture-derived Sarcocystis sp. merozoites in which the particular isolate was originally derived from a naturally infected cat with tissue sarcocysts. This is in contrast to cats which did not develop tissue cysts when inoculated with S. neurona merozoites originally derived from a horse with EPM. These results indicate present biological differences between the culture-derived merozoites of two Sarcocystis isolates, Sn-UCD 1 and Sn-Mucat 2.     

Development of sarcocysts of Sarcocystis levinei in water buffalo infected with sporocysts from dogs

Half a million sporocysts of Sarcocystis levinei obtained from experimentally infected dogs were fed to a buffalo calf, and sarcocysts of this species were recovered from its oesophageal muscles when the animal was killed on the 62nd day of inoculation, thus establishing a buffalo-dog-buffalo cycle.     

Influence of size of sporocyst inoculum upon the size and number of sarcocysts of Sarcocystis falcatula which develop in the brown-headed cowbird

The influence of the number of sporocysts in the inoculum of Sarcocystis falcatula on the morphology of the sarcocysts has not been reported in the literature. To determine if there is a relationship, different number of sporocysts were inoculated orally into wild-caught cowbirds. After 14 weeks, the cowbirds were euthanised and muscle tissue was examined grossly and by histologic sections. Sarcocysts were compared based on the numbers which developed and their sizes. There was a linear increase in the number of sarcocysts as the size of the inoculum increased, however, the size of the sarcocysts became smaller with the increase in number of sporocysts inoculated.     

Biochemical and histochemical studies of the sarcocyst of Sarcocystis fusiformis of buffalo Bubalus bubalis

The glycogen content and activities of alkaline and acid phosphatases of sarcocysts of Sarcocystis fusiformis from naturally infected Indian water buffalo (Bubalus bubalis) were determined biochemically and histochemically.     

Sarcocystis calchasi encephalitis in a rock pigeon

A rock pigeon (Columba livia) caught in Akihabara, Tokyo, showed neurological symptoms, such as head tilt and circling. Pathological examinations revealed abundant Sarcocystic cysts in the skeletal muscle and myocardium with mild myositis, and numerous schizonts and sarcocysts with severe multifocal granulomatous T-lymphocytic infiltration in the central nervous system. A Sarcocystis calchasi-specific gene was detected in the muscle and brain. This case indicates S. calchasi was distributed in Japan and caused severe encephalitis to rock pigeons.