Prevalence and site specificity of Sarcocystis greineri sarcocysts in Virginia opossum (Didelphis virginiana) in Florida

Sarcocysts of Sarcocystis greineri in the Virginia opossum (Didelphis virginiana) were observed for documenting sarcocyst prevalence, seasonal prevalence, and muscle specificity. Characteristics of sarcocysts found in striated muscle were recorded, as were light microscopy measurements. Overall prevalence of sarcocysts in striated muscle was 10.0% (24/240). No statistical difference (P = 0.156) in prevalence was detected between summer (13.1%; 16/122) and fall (6.7%; 8/118). Sarcocysts were found in muscles of the diaphragm, leg, breast, tongue, back, and esophagus. Diaphragm had the highest specificity of 72.7% (8/11), which was significantly different (P = 0.05) when compared with tongue and esophagus at 16.6% (1/6). Breast and leg muscle had a specificity of sarcocysts of 54.5% (6/11), whereas 27.2% (3/11) of back muscles contained sarcocysts.     

Sarcocystis of deer in South Dakota

The prevalence of Sarcocystis in white-tailed deer (Odocoileus virginianus) and mule deer (O. hemionus) in South Dakota was determined through microscopic examination of tongue samples. The percentage of Sarcocystis infection for both species of deer was determined for prairies east of the Missouri River, west of the Missouri River, and Black Hills of western South Dakota. Sixteen percent (N = 62) of the white-tailed deer tongues from East River, 69% (N = 42) from West River, and 74% (N = 23) from the Black Hills were infected. Prevalence for mule deer was 88% (N = 24), 78% (N = 63), and 75% (N = 12) from East River, West River, and the Black Hills, respectively. Of 50 tongue samples obtained from both species of deer during a special antlerless deer hunt in the Black Hills in 1978, 66% were infected. Coyotes (Canis latrans), dogs (Canis familiaris), red foxes (Vulpes vulpes), a gray fox (Urocyon cinereoargenteus), bobcat (Felis rufus), and raccoon (Procyon lotor) were fed muscle from white-tailed deer and mule deer naturally infected with Sarcocystis to determine their role as definitive hosts. All coyotes, dogs, and the gray fox shed sporocysts, while none were recovered from the other animals. Sporocysts shed by coyotes were counted and concentrated into an inoculum and administered to a white-tailed deer fawn, which was necropsied 85 days after inoculation. Sections of heart, tongue, esophagus, diaphragm, and skeletal muscle were found to be heavily infected with sarcocysts, while sarcocysts were not detected in a control fawn.     

Sarcocystis in Muscles of Raccoons (Procyon lotor L.)1

Sarcocysts of Sarcocystis sp. were found in 26 (50%) of 52 raccoons (Procyon lotor) from Ohio, Pennsylvania, Florida, and Maryland. Although only 4 (7.7%) of 52 cardiac muscle specimens were found to contain sarcocysts, 25% to 36.5% of tongue, diaphragm, masseter muscle, and esophagus specimens were found infected. By light microscopy, sarcocyst walls were <3 μm thick and had no conspicuous projections; interior septa were indistinct. By transmission electron microscopy, sarcocyst walls had short (mean = 2.7 μm), villus-like protrusions; thin septa were seen within the sarcocysts. The raccoon may be an intermediate host for a Sarcocystis sp. that completes its life cycle in an unidentified, wild carnivore.     

Sarcocystis in muscles of raccoons (Procyon lotor L.)

Sarcocysts of Sarcocystis sp. were found in 26 (50%) of 52 raccoons (Procyon lotor) from Ohio, Pennsylvania, Florida, and Maryland. Although only 4 (7.7%) of 52 cardiac muscles specimens were found to contain sarcocysts, 25% to 36.5% of tongue, diaphragm, masseter muscle, and esophagus specimens were found infected. By light microscopy, sarcocyst walls were less than 3 micron thick and had no conspicuous projections; interior septa were indistinct. By transmission electron microscopy, sarcocyst walls had short (mean = 2.7 micron), villus-like protrusions; thin septa were seen within the sarcocysts. The raccoon may be an intermediate host for a Sarcocystis sp. that completes its life cycle in an unidentified, wild carnivore.     

Cylicospirura species (Nematoda: Spirocercidae) and stomach nodules in cougars (Puma concolor) and bobcats (Lynx rufus) in Oregon

The stomachs and proximal duodena of 160 cougars (Puma concolor) and 17 bobcats (Lynx rufus), obtained throughout Oregon during 7 yr, were examined for Cylicospirura spp. and associated lesions. Prevalence in cougars was 73%, with a range in intensity of 1-562 worms. The mean diameter of nodules was 1.2 cm (SD=0.5), and many extended through the submucosa to the muscularis. About 83% of cougars had nodules; most nodules contained worms, but 14% of the smaller nodules (<0.2 cm) contained porcupine (Erethizon dorsatum) quills. A mean of 12.4 worms/nodule (SD=34.1) was observed, with a maximum of 340 worms/nodule. Prevalence in bobcats was 53%, with an intensity of 1-25 worms. About 65% of bobcats had nodules, which were slightly smaller than those in cougars but appeared to involve similar layers of gastrointestinal tissue. One to 25 Cylicospirura sp. were found in all but two small nodules in bobcats. Cougars killed for livestock damage or safety concerns had a significantly higher median worm intensity than did those that died of other causes. Also, the median worm intensity of older cougars was higher than that of younger lions. There were more males than females killed for livestock damage or safety concerns. The cylicospirurid from cougars was Cylicospirura subaequalis, and that of bobcats was Cylicospirura felineus. These two similar species were separated morphologically by differences in tooth and sex organ morphology. They were also differentiated by DNA sequence analysis of the mitochondrial cytochrome c oxidase subunit 1 gene (cox1). Worm sequences from cougars differed from those from bobcats by 11%, whereas essentially no difference was found among worms from the same host. Phylogenetic analysis showed that within the order Spirurida, both cylicospirurids were most closely related to Spirocerca lupi, based on this gene sequence.     

The role of birds as definitive hosts and intermediate hosts of heteroxenous coccidians

Sarcocystis-like oocysts-sporocysts were found in four species of owls (Asio otus, Bubo bubo, Strix aluco, and Tyto alba) and in five species of predatory birds (Accipiter gentilis, Accipiter nisus, Buteo buteo, Circus aeruginosus, Falco tinnunculus). In addition, the muscles of 15 of 41 (36.5%) pheasants (Phasianus colchicus) and one of two jays (Garrulus glandarius) were found to harbor three types of Sarcocystis. Three of 15 (20%) infected pheasants had type I cystozoites (6-8 X 2 microns) in muscle homogenates, but sarcocysts were not seen whereas the other 12 infected pheasants had type II cystozoites (16 X 2-3 microns) and sarcocysts (90 X 600 microns) in their muscles. The one infected jay had type III cystozoites (8-10.5 X 2.5-3 microns) and sarcocysts (35-40 X greater than 770 microns) in its muscles.     

Two new species of Sarcocystis (Apicomplexa: Sarcocystidae) infecting the wolverine (Gulo gulo) from Nunavut, Canada

Infection with Sarcocystis species is common in many species of animals, but it has not yet been reported in wolverines (Gulo gulo). Histological sections of tongues from 41 wolverines in the Kitikmeot Region, Nunavut, Canada, were examined for sarcocysts. Sarcocysts were found in 33 (80.4%) wolverines. Two structurally distinct types of sarcocysts were found. Type A sarcocysts were thin (<1 μm thick) walled. Ultrastructurally, the parasitophorous vacuolar membrane (Pvm) had minute undulations, but it lacked villar protrusions and was not invaginated into the granular layer. The bradyzoites were slender, about 5 × 1 μm in size. Structurally, these sarcocysts were distinct from known species of Sarcocystis and possessed a novel 18S and ITS-1 sequence, sharing 98% and 78% sequence similarity with Sarcocystis canis . A new species name, Sarcocystis kalvikus, is proposed for type A sarcocysts. In contrast, type B sarcocysts had relatively thicker (about 2 μm) cyst walls and larger bradyzoites, each about 10 × 2-3 μm. Ultrastructurally, the Pvm on the sarcocyst wall had villar protrusions that were either mushroom-like or sloping. Molecular analysis identified a unique 18S and ITS-1 sequence that placed them in a clade within the Sarcocystidae. Based on histology, TEM, and genetic data, the new name, Sarcocystis kitikmeotensis, is proposed. Sarcocystis kalvikus was found in 14 (34.1%), S. kitikmeotensis was found in 7 (17%), and both species were found in 12 (29.2%) of 41 wolverines.     

The Role of Birds as Definitive Hosts and Intermediate Hosts of Heteroxenous Coccidians

ABSTRACT. Sarcocystis- like oocysts-sporocysts were found in four species of owls (Asio otus, Bubo bubo, Strix aluco , and Tyto alba) and in five species of predatory birds (Accipiter gentilis, Accipiter nisus, Buteo buteo. Circus aeruginosus, Falco tinnunculus). In addition, the muscles of 15 of 41 (36.5%) pheasants (Phasianus colchicus) and one of two jays (Garrulus glandarius) were found to harbor three types of Sarcocystis. Three of 15 (20%) infected pheasants had type I cystozoites (6-8 × 2 fim) in muscle homogenates, but sarcocysts were not seen whereas the other 12 infected pheasants had type II cystozoites (16 × 2-3 pm) and sarcocysts (90 × 600 μm) in their muscles. The one infected jay had type III cystozoites (8-10.5 × 2.5-3 μm) and sarcocysts (35-40 × >770 μm) in its muscles.     

Development of Ox-Coyote Cycle of Sarcocystis cruzi1

The ox-coyote cycle of Sarcocystis cruzi was studied by killing 38 calves between 4 and 153 days postinoculation (DPI) with 55 × 10³-5 × 10⁸ sporocysts from the intestines of coyotes. At 4 DPI, a zoite was found within the lumen of a mesenteric lymph node artery. At 7 DPI, zoites were found in mononuclear cells and in endothelial cells in mesenteric arteries. First generation meronts (41.0 × 17.5 μm in diameter) occurred 7–26 DPI in mesenteric lymph nodes. At 19–46 DPI, second generation meronts occurred in kidneys, muscles, and other tissues: renal meronts were 19.6 × 11.0 μm, and intramuscular meronts were 25.0 × 11.1 μm. Merozoites were found in the peripheral blood 17 DPI and later at 24–46 DPI. They divided by endodyogeny in mononuclear cells. Sarcocysts were seen first in the heart at 45 DPI and contained one or two metrocytes. At 55 DPI, sarcocysts containing only metrocytes were found in striated muscles, heart, and in smooth muscles of the urinary bladder, rumen, omasum, abomasum, and small intestine. At 67, 87, 112, and 153 DPI, sarcocysts were found only in striated muscles and in the heart. At 67 DPI, sarcocysts were up to 360 μm long. They contained only metrocytes and were not infective to the dog. At 86 DPI, sarcocysts contained mostly bradyzoites, a few metrocytes, and were infective to a coyote. The thin-walled sarcocysts grew to a maximum length of 800 μm and contained bradyzoites that were 10.9 × 3.0 μm. At 90 DPI, two mature sarcocysts were found in 2 of 73 sections of brain and spinal cord; hundreds of sarcocysts were present in sections of tongue and heart of this calf. Gametogony occurred in the small intestine of the coyote. Macro-and microgamonts were found in goblet cells of the small intestines of coyotes 6 h after the ingestion of infected meat. Microgamonts were few and contained 3–11 slender gametes. Oocysts were seen at 12 h and sporulation was completed 9 DPI. The prepatent period in the coyote was 8 days. The ox-coyote cycle is compared with ox-dog cycle.     

Prevalence and development of two Sarcocystis spp. in the horse (author's transl)

The prevalence of Sarcocystis spp. in horses was investigated in a survey at the Munich abattoir during 1978/79. Muscle specimens (oesophagus, diaphragm, sublingual muscle, myocardium) were examined using tryptic digestion. Out of 200 horses 31 (15.5%) were found to be carriers of sarcocysts. No parasites were found in the myocardium. In three animals sarcocysts could be isolated and differentiated in fresh preparations. Cysts with 5 to 11 microns by less than 0.5 microns hairlike, unstable protrusions were classified as Sarcocystis equicanis, whereas those with 2.5 to 4.5 microns by 0.8 to 1.0 microns fingerlike, stabile protrusions were assigned to be S. fayeri. Histologically S. equicanis cysts were thin-walled and S. fayeri cysts were thick-walled and often striated. For both species the dog acts as final host. A mixture of sporocysts of both species measured: 12.0--14.4 (13.4 +/- 0.7) X 9.3--10.5 (9.8 +/- 0.4) microns. The prepatent period is 11 to 17 days. Two ponies experimentally infected with 100,000 sporocysts each did not show clinical signs. In fresh preparations and in histopathological examinations of biopsied (111th, 130th, 152th, and 165th day post-infection (p.i.) and postmortem material (167th and 189th day p.i.) different developmental stages of sarcocysts of both species were seen and the following pathological alterations observed: circumscribed non-purulent inflammation, moderate Zenker's degeneration of muscle fibres, and degenerated cysts, of which sometimes only parts of the cyst wall were left. In fresh preparations S. equicanis and S. Fayeri could be differentiated 111 days p.i. The observed disappearance of the sarcocysts is suggested to be a self-cleaning process.     

Sarcocystis mephitisi n. sp. (Protozoa: Sarcocystidae), Sarcocystis neurona-like and Toxoplasma-like infections in striped skunks (Mephitis mephitis)

Two structurally distinct types (A, B) of microscopic sarcocysts were found in muscles of 4 of 5 feral skunks. Type A sarcocysts had sarcocyst walls of up to 6 microm thick. The villar protrusions (Vp) on the sarcocyst wall were up to 5 microm long. The Vp were constricted at the base, expanded in the middle, and had a blunt tip. Numerous microtubules were present in the Vp and in the granular layer. Bradyzoites were up to 11 microm long and up to 3.2 microm wide. Based on the distinctiveness of the Vp, a new name, Sarcocystis mephitisi is proposed for type A sarcocysts. Type B sarcocysts had a relatively thin (approximately 1-2 microm thick) sarcocyst wall and the Vp were slender and tapered toward the tip. These sarcocysts were structurally similar to S. neurona sarcocysts. A Toxoplasma gondii-like tissue cyst was found in a section of tongue of 1 of the 4 skunks.     

Sarcocystis arieticanis and other Sarcocystis species in sheep in the United States

Histological sections of tongues, esophagi, and diaphragms from 512 adult ewes from the northwest United States and Texas were examined for Sarcocystis spp. Sarcocysts were found in sections of 82.1% of 504 tongues, 44.4% of 478 esophagi, and 51.7% of 89 diaphragms. Sarcocystis tenella was the predominant species and was found in 430 (84.0%) sheep; S. arieticanis was found in 18 (3.5%) sheep. The mean number of S. tenella sarcocysts in tissue sections was approximately 10 times higher than that of S. arieticanis. The identification of S. arieticanis was confirmed by ultrastructural studies and by transmission to dogs. Macroscopic sarcocysts of S. gigantea were also found but were not quantitated in all sheep; sarcocysts of S. medusiformis were not observed.     

Clinical muscular sarcocystosis in a dog

Muscular sarcocystosis is a rare infection in dogs. Clinical myositis associated with an unidentified species of Sarcocystis was diagnosed in an adult dog from Canada. There was granulomatous myositis associated with numerous immature sarcocysts in a muscle biopsy obtained from the dog. The sarcocysts were up to 550 microm long and up to 45 microm wide. The sarcocyst wall was approximately 1 microm thick and contained short, stubby, villar protrusions that lacked microtubules. This is the first report on clinical muscular sarcocystosis in a dog.     

Prevalence of sarcocysts in Florida black bears (Ursus americanus floridanus)

Sections of muscle from Florida black bears (Ursus americanus floridanus) collected in the state of Florida were observed for the presence of Sarcocystis sp. sarcocysts. Two of 132 (1.5%) black bears had muscle sections containing sarcocysts. One sarcocyst was observed per muscle section. The sarcocysts averaged 181.5 x 99.0 microm by light microscopy of hematoxylin and eosin-stained sections.     

Sarcocystosis among Wild Captive and Zoo Animals in Malaysia

Sarcocystis sp. infection was investigated in 20 necropsied captive wild mammals and 20 birds in 2 petting zoos in Malaysia. The gross post-mortem lesions in mammals showed marbling of the liver with uniform congestion of the intestine, and for birds, there was atrophy of the sternal muscles with hemorrhage and edema of the lungs in 2 birds. Naked eye examination was used for detection of macroscopic sarcocysts, and muscle squash for microscopic type. Only microscopically visible cysts were detected in 8 animals and species identification was not possible. Histological examination of the sections of infected skeletal muscles showed more than 5 sarcocysts in each specimen. No leukocytic infiltration was seen in affected organs. The shape of the cysts was elongated or circular, and the mean size reached 254 × 24.5 µm and the thickness of the wall up to 2.5 µm. Two stages were recognized in the cysts, the peripheral metrocytes and large numbers of crescent shaped merozoites. Out of 40 animals examined, 3 mammals and 5 birds were positive (20%). The infection rate was 15% and 25% in mammals and birds, respectively. Regarding the organs, the infection rate was 50% in the skeletal muscles followed by tongue and heart (37.5%), diaphragm (25%), and esophagus (12.5%). Further ultrastructural studies are required to identify the species of Sarcocystis that infect captive wild animals and their possible role in zoonosis.     

Life cycle of Sarcocystis neurona in its natural intermediate host,the raccoon,Procyon lotor

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.     

Ultrastructural development of the sarcocyst of Sarcocystis rauschorum (Apicomplexa: Sarcocystidae) in the varying lemming Dicrostonyx richardsoni

The development of the sarcocyst of Sarcocystis rauschorum in its intermediate host was studied. Lemmings were orally administered sporocysts of S. rauschorum obtained from snowy owls (Nyctea scandiaca). Beginning at 9 days postinoculation (DPI) and at various intervals to 84 DPI, skeletal muscle tissue taken from the infected lemmings was examined by electron microscopy. At 9 DPI the sarcocysts contained few metrocytes and the cyst wall was flat. The metrocytes underwent endodyogeny, and within a few days the cyst wall of the rapidly growing sarcocyst developed numerous tubulovesicular invaginations into the electron-dense layer, and the wall had a few irregular infoldings. By 21 DPI, banana-shaped bradyzoites appeared, and by 84 DPI the mature cysts were filled with bradyzoites in groups subdivided by septa and by deep infoldings of the cyst wall. The fine structure of the wall remained simple throughout maturation, with no conspicuous invagination or protrusion. The sarcocyst produced in response to S. rauschorum is unlike those from many species of Sarcocystis, which have complex walls that change markedly as the sarcocysts mature; however, its simple appearance is similar to other species that have rodents as intermediate hosts and raptorial birds as definitive hosts.     

A new species of Sarcocystis (Apicomplexa: Sarcocystidae) from the black bear (Ursus americanus)

Infection with Sarcocystis species is common in herbivores but is rare in bears. Histological sections of 374 black bears (Ursus americanus) from Pennsylvania were examined for sarcocysts. In total, 3 sarcocysts were found in 3 bears, with 1 sarcocyst per section. Sarcocysts from 2 bears were considered a new species, Sarcocystis ursusi. Sarcocysts of S. ursusi n. sp. were microscopic and contained only bradyzoites. By light microscopy, the sarcocyst wall was thin (< 0.5 microm thick) and had minute serrations. Ultrastructurally, the serrations on the sarcocyst wall consisted of villar protrusions (Vp) that were mostly 0.5 microm long. The Vp had bundles of electron-dense microtubules that were as wide as long; these microtubules extended deep into the ground substance layer, a feature that distinguished this species from unnamed sarcocysts from black bear. Bradyzoites were 4.8-6.0 microm long. The sarcocyst from the third bear was structurally different from S. ursusi; its sarcocyst wall was approximately 2 microm thick and had finger-like villi on the cyst wall giving the sarcocyst wall a striated appearance.     

Acute Sarcocystis falcatula-like infection in a carmine bee-eater (Merops nubicus) and immunohistochemical cross reactivity between Sarcocystis falcatula and Sarcocystis neurona

An unidentified Sarcocystis falcatula-like infection was diagnosed in a captive bee-eater (Merops nubicus) in a zoo in Florida. The bird died suddenly, probably due to protozoa-associated pneumonia. Protozoal schizonts were found in lungs and heart, and immature sarcocysts were seen in skeletal muscles. Ultrastructurally, schizonts were located in capillary endothelium and merozoites lacked rhoptries, consistent with the structure of Sarcocystis species. Sarcocysts were immature, microscopic, and contained only metrocytes. The sarcocyst wall had finger-like villar protrusions that were up to 0.7 microm long and up to 0.2 microm wide. The villar protrusions lacked microtubules, characteristically seen in sarcocysts of S. falcatula. Antigenically, parasites in lungs and muscles of the bee-eater reacted with a varying intensity with polyclonal rabbit antisera to S. falcatula and Sarcocystis neurona. Results indicated that sarcocysts in the bee-eater were morphologically different from the reported structure for sarcocysts of other S. falcatula infections.