Sarcocystis infection in wild reindeer (Rangifer tarandus) from Hardangervidda in southern Norway: with a description of the cysts of Sarcocystis hardangeri n. sp

Fresh preparations of micro-isolated sarcosysts from skeletal muscle of 5 wild reindeer were examined by light microscopy. Slender, spindelshaped cysts measuring 821 × 60 µm, and having short knob-like cyst wall protrusions were found in all animals. In 1 animal cysts different in structure from the cysts of the 4 previously known Sarcocystis spp. of reindeer were found, These cysts are considered to be cysts of a new Sarcocystis sp. of reindeer, for which the name Sarcocystis hardangeri has been proposed.S. hardangeri n. sp. had macroscopic, ovoid to cylindrical cysts measuring 1667 (900–2570) × 819 (450–1575) µm. The cysts were surrounded by a 8–10 µm thick layer of fibrillar material. After removal of this layer, relatively few and irregularly spaced, slanting protrusions became visible. The 20–30 µm long protrusions were tongue-like, and were lying close to the surface of the cyst.Cysts of S. grueneri, S. rangiferi and S. tarandi were not demonstrated in the 5 wild reindeer examined.     

Sarcocystis hardangeri and Sarcocystis rangi n. sp. from the domestic reindeer (Rangifer tarandus) in northern Norway

Fresh preparations of microisolated sarcocysts from striated muscle of several domestic reindeer from northern Norway were examined by light microscopy. In cardiac muscle, cysts of S. grueneri were found. In skeletal muscle, cysts of S. rangiferi, S. tarandi and S. tarandivulpes were found in all samples examined. In the abdominal muscles of some reindeer, one or two other types of cysts were found.Cysts of one type were macroscopic in size, and ovoid to cylindrical in shape. The cysts were surrounded by a 8–12 µm thick layer of fibrous material, and measured 1682×910 µm. The cysts had relatively few and irregularly distributed, 20–35 µm long, and 3–5 µm wide, linguiform cyst wall protrusions, which could only be seen after removal of the fibrous layer. These cysts were classified as cysts of S. hardangeri, a species previously described from wild reindeer in southern Norway.Cysts of the other type were long and slender, measuring 5460–12700 (8994 ± 2575) × 95–280 (180 ± 50) µm. The cysts had numerous very fine, flexible, hair-like cyst wall protrusions, which were 8–10 [xm long and less than 0.5 µm thick. These cysts are considered to belong to a new Sarcocystis species of reindeer, for which the name Sarcocystis rangi n, sp. is proposed. The reindeer is recorded as the intermediate host for 6 different species of Sarcocystis.     

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.     

The raccoon dog (Nyctereutes procyonoides) as definitive host for Sarcocystis spp. of reindeer (Rangifer tarandus)

A raccoon dog (Nyctereutes procyonoides; Family: Canidae), was given cardiac muscle of reindeer infected with S. grueneri, and started shedding Sarcocystis sporocysts 10 days post feeding. The sporocysts measured 13.9 (12.4–15.7) × 10.1 (9.2–11.2) µm, and were excreted for at least 16 days. The raccoon dog is thus an additional definitive host for S. grueneri (Yakimoff & Sokoloff, 1934) Gjerde, 1984.Another raccoon dog was given skeletal muscle infected with 4 species of Sarcocystis, none of which was S. grueneri. The raccoon dog started shedding Sarcocystis sporocysts on day 10 post feeding, and excreted sporocysts for at least 16 days. The sporocysts measured 14.0 (12.3–15.6) × 10.1 (9.2–11.2) µm, and are considered to be sporocysts of S. tarandivulpes Gjerde, 1984.This is the first record of the raccoon dog as an experimental definitive host for Sarcocystis.     

Sarcocystis sinensis is an ultrastructurally distinct parasite of water buffalo that can cause foodborne illness but cannot complete its life-cycle in human beings

In this study, we compared the morphology of Sarcocystis sinensis and Sarcocystis hominis, and assessed the infectiousness of S. sinensis for human volunteers. The cysts of S. sinensis were from water buffalo (Bubalus bubalis) and those of S. hominis were from cattle (Bos taurus). Transmission electron microscopy of S. sinensis cysts revealed that the cyst wall had leaning, finger-like protrusions measuring 1.44-5.08 μm in length and without invaginations on the tip surface of the protrusions. In contrast, the cyst wall of S. hominis had upright, finger-like protrusions measuring 9.43 μm×2.42 μm and with vesicle-like invaginations on the tip surface of the protrusions. Scanning electron microscopy revealed that surface of the protrusions was arranged as rectangles in S. sinensis, as compared to tongue-shaped in S. hominis. Other distinguishing features of S. sinensis include a thin ground substrate (GS) zone with microtubules and small, circle-like structures located at the base of the protrusions. Human volunteers, after consuming S. sinensis cysts, produced no sporocysts or oocysts in feces, suggesting that humans could not serve as definitive hosts for S. sinensis. By contrast, many sporocysts and oocysts were passed in feces of a human volunteer 11-29 days after ingestion of S. hominis cysts. These results showed that S. sinensis and S. hominis are separate species and S. sinensis cannot use human being as the definitive host.     

The structure and identity of macroscopically visible Sarcocystis cysts in cattle

Macroscopically visible Sarcocystis spp. cysts isolated from the skeletal muscle of slaughtered cattle were examined by light- and electronmicroscopy. Transmission experiments involving cats, dogs and a human volunteer were also carried out. The cysts could only be transmitted to cats which establishes them with a high degree of certainty as Sarcocystis hirsuta. The cyst wall (including protrusions) ranged from 3.3 to 7.0 micron in thickness and the individual cyst wall protrusions from 1.2 to 2.6 micron in width. Transmission and scanning electronmicroscopy revealed previously undescribed features of the cyst wall. It appears that, with increasing age, the cyst wall protrusions become larger and develop a highly irregular surface. Their attachments to the cyst wall are slender and widely spaced indicating that growth of the cyst continues without the formation of new protrusions. Within the protrusions the fibrils become disorganised and numerous osmiophilic granules appear. It is evident that major changes in the structure of sarcocysts can occur with age.     

Ultrastructure of the cysts of Sarcocystis tarandivulpes from skeletal muscle of reindeer (Rangifer tarandus tarandus)

The cysts of S. tarandivulpes were found to be limited by a unit membrane which has been called the cyst membrane. The surface of the cysts was covered by closely packed and hexagonally arranged knob-like protrusions. The protrusions were 0.6–1.2 μm long and had an elliptical cross section. At the base of and between the bases of the protrusions the cyst mem brane was raised into low anastomosing folds which delineated shallow compartments. Between the folds the cyst membrane formed small vesicle-like invaginations into the cyst. On the apical part of the protrusions the cyst membrane had a smooth contour and was underlined by 2 layers of electron-dense material. Cyst ground substance divided the interior of the cyst into compartments containing either metrocytes or cystozoites. Cystozoites undergoing endodyogeny were present among the nondividing cystozoites. Some new terms were introduced to denote structures at the border of the cyst. The old terms are reviewed and the structural resemblance between S. tarandivulpes and S. odocoileocanis from Odocoileus virginianus is discussed.     

Sarcocystis sp. from cattle slaughtered in Japan

Sarcocystis sp. was detected from cattle slaughtered in Saitama Prefecture, Japan. The cysts were 3,400-4,400 x 198-238 microm in size and had the thick cyst wall which was 7 to 10 microm thick and provided with finger-like villar protrusions. The protrusions were 8-9.5 x 2-2.5 microm in size and had microtubules in the core.     

Naturally occurring Sarcocystis neurona-like infection in a dog with myositis

Tissue stages similar to those of Sarcocystis neurona, the causative agent of equine protozoal myeloencephalitis, were identified in skeletal muscles of a dog. The dog, a 6-year-old Labrador retriever, was seropositive for Toxoplasma gondii infection and euthanized due to a history of polymyositis and progressive muscular atrophy. Histologically, 30, variably sized, microscopic, intracellular sarcocysts were observed in 60 sections of skeletal muscles taken from the neck, fore limbs and hind limbs. The cysts were only observed in inflamed skeletal muscles, but were mostly in myocytes at the periphery of areas infiltrated with leukocytes. Ultrastructurally, the cyst wall had villar protrusions consistent with sarcocysts. Immunohistochemistry with monoclonal S. neurona antibodies demonstrated positive labeling of zoites in merozoites or schizonts in the skeletal muscle interstitium, but no labeling of the sarcocysts. Initial PCR analysis with primers amplifying a genetic sequence encoding Apicomplexan 18s rRNA, and subsequent PCR analysis with differentiating primers indicated that the genetic sequences had 100% identity with sequences reported for S. neurona.     

Experimental infection with Sarcocystis medusiformis in sheep

The development of the parasite was studied in 48 sheep killed between 188 and 1132 days after experimental inoculation with Sarcocystis medusiformis sporocysts from cats. Immature sarcocysts were present at 188 days post inoculation (d.p.i.). At 331 d.p.i. macroscopic sarcocysts with an elongate fusiform appearance were seen in the laryngeal, abdominal and diaphragm musculature. The largest cyst measured 2 mm in length by 0.5 mm in width at 331 d.p.i.; histologically they contained metrocytes at the periphery of the cyst with more densely staining merozoites in the central region. By 443 d.p.i. typical 'thin' cysts 2-3.5 mm in length were seen in the flank and external thoracic muscles. By 765 d.p.i. sarcocysts were 5 mm in length. The ultrastructure of the cyst wall of these cysts resembled that of S. medusiformis. At 1132 d.p.i. sarcocysts measured 4 mm X 0.5 mm.     

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.     

Prevalence pattern and biology of Sarcocystis capracanis infection in the Egyptian goats: a light and ultrastructural study

Cysts of Sarcocystis capracanis obtained from infected goats were examined to clarify the effect of the parasite on the host. Muscle tissues from fresh oesophagus, tongue, diaphragm and skeletal muscles of 680 goats were slaughtered in the main abattoir of Cairo, Egypt and they were examined microscopically for Sarcocystis infection for the first time in Egypt. 540 out of 680 (79.4%) of examined goats were found to be infected with Sarcocystis sp. The infection was recorded firstly by light microscopy as spindle shaped cysts embedded in the muscle tissues. The validity of this species as S. capracanis was confirmed by means of ultrastructural characteristics of the primary cyst wall which revealed the presence of thick-radially striated wall with finger like projections, underlined by a thick layer of ground substance enclosing the developing metrocytes and merozoites that usually contain nearly all the structures of the apical complex and fill the interior cavity of the cyst. The cyst cavity is divided by many septa extending from the ground substance and producing large number of chambers. An experimental infection using the highly infected muscles was carried out to determine the final host, which is dog. Smears of intestinal epithelium were taken to examine the endogenous stages (gamogony and sporogony) by means of light microscopy. These stages were mainly observed as to infect the lamina propria of the posterior third of the small intestine. Gamogony and zygote formation (fertilization) occurred 2-8 days post infection, while sporulation took place within the final host 13-15 days and sporocysts were passed within faeces of the infected puppies at that time. The prepatent period of S. capracanis was 12-15 days, while the patent period was extended to 37 days. In goats, infection with S. capracanis led to the loss of weight, anaemia, abortion and even death in cases of heavy infection. While bleeding, watery faeces filled with mucous on 5th and 8th day p.i. as well as intestinal lesions are the pathogenic effects occurred in puppies after experimental infection.     

Morphology of Sarcocystis gigantea in experimentally-infected sheep

The development of the parasite and lesions was studied in 32 sheep killed 10 days to 47 months after inoculation with Sarcocystis gigantea sporocysts from cats. At 21-42 days post-inoculation (d.p.i.), there was a mild encephalitis, but organisms were not seen in the brain. Immature sarcocysts were detected from 40-84 d.p.i. The cyst wall was not measurable by light microscopy at 40 d.p.i., but was 1.5-2 microns thick at 84 d.p.i. At 119 d.p.i. both immature cysts containing only metrocytes, and mature cysts containing both metrocytes and merozoites, were present. These mature cysts did not have a secondary cyst wall. A mature cyst, 350 microns in length, was found in a sheep killed at 8 1/2 months p.i. At 10 m.p.i. cysts were up to 0.5 mm long and a secondary cyst wall was present. At 47 m.p.i. cysts were 2-5 X 4.5-7.5 mm, and were found only in the muscles of tongue, oesophagus, pharynx and flank.     

驴肉孢子虫包囊的超微结构及其实验感染

对昆明地区的26头驴进行了肌肉检查，在24头驴肌肉中发现了肉孢子虫包囊，其然自感染率为92．3％，光镜下包囊呈梭形，具有锥状和棍棒状的突起，透射电镜下突起内微管在顶端松散排列，向下延伸集结成束，斜伸入基质层，有的和母细胞的膜相连，用含有包囊的驴肉实验感染犬和猫各2只，感染后在犬粪便中发现孢子囊和卵囊，潜隐期为11－13 d，剖检在2只犬的小肠固有层中查到孢子囊和卵囊，猫粪便中一直未检到孢子囊和卵囊，剖检亦未发现，表明驴肉孢了虫的终末宿主要是犬，而是猫，研究认为驴全内的肉孢子虫仅有1种，鉴定为柏氏肉孢子虫（Sarcocystis bertrami).     

First isolation of Sarcocystis hominis from cattle in Japan.

Sarcocystis hominis was first isolated from slaughtered cattle raised in Japan. Cysts were 1,220-4,460 x 80-384 microns in size and their wall was 3 to 6 microns thick and appeared radially striated in the histopathological sections because of the presence of palisade-like villar protrusions on the surface. The protrusions were 3.1-4.3 x 0.7-1.1 microns in size and had many microtubules in the core. Two cynomolgus monkeys, Macaca fascicularis, fed with the Sarcocystis cysts began to pass sporocysts, which measured a size of 14.3-15 x 9.5-10 microns, in the feces 10 days after ingestion.     

Prevalence of thin-walled <Emphasis Type="Italic">Sarcocystis cruzi</Emphasis> and thick-walled <Emphasis Type="Italic">Sarcocystis hirsuta</Emphasis> or <Emphasis Type="Italic">Sarcocystis hominis</Emphasis> from cattle in Iran

Bovine sarcocystosis is caused by Sarcocystis cruzi and is known to cause considerable morbidity and mortality in cattle. This species is distributed worldwide in cattle and is the most prevalent of the Sarcocystis species infecting cattle. There is high infection rate of sarcocyst in cattle in Iran, but to our knowledge, there is no study about identification of Sarcocystis species. This work aimed to survey prevalence of S. cruzi cyst in slaughtered cattle of Isfahan, Iran. In this study, esophageal and diaphragmatic muscles of 100 cattle were collected from Fesaran abattoir of Isfahan and examined for the presence of Sarcocystis spp. cysts macroscopically and microscopically. No macroscopic sarcocysts were found in any of the samples. In light microscopy, 89 out of 100 cattle (89%) had thin-walled cysts of S. cruzi, while 21 out of them (21%) had thick-walled sarcocysts. In addition to light microscopy, ultrastructural features of the thin-walled cyst confirmed the presence of S. cruzi.     

Ultrastructure of Sarcocystis spp. from donkeys (Equus asinus) in Egypt

The fine structure of Sarcocystis spp. from donkeys (Equus asinus) in Egypt is described. Sarcocysts were found in the oesophagus, diaphragm and heart of 18 of 20 donkeys. Only one type of mature muscle cyst was found. Sarcocysts were 120-410.6 X 48.4-50.2 microns. The primary cyst wall had numerous 3.3-3.7 microns villi. Each villus contained 20-60 fibrillar elements which extended from the ends and sides of the villi throughout the ground substance, where they became tightly packed. The bundles of fibrillar elements formed junctions with the pellicles of the metrocytes. Ultrastructurally, Sarcocystis spp. of the donkey was similar to sarcocysts previously described from the horse.     

The prevalence and identity of Sarcocystis in beef cattle in New Zealand

Muscle tissue from the oesophagus and diaphragm of 500 beef cattle slaughtered in New Zealand was examined for Sarcocystis infection by microscopic examination of cysts isolated from muscle samples. All cattle were infected with Sarcocystis; based on light microscopy of cysts, 98% had thin-walled Sarcocystis cruzi cysts and 79.8% had thick-walled (Sarcocystis hirsuta/Sarcocystis hominis) cysts. Cysts were also collected for electron microscopy and transmission experiments. Thick-walled cysts could not be distinguished as S. hirsuta or S. hominis by light or electron microscopy. Thick-walled cysts were fed to three cats and one human volunteer; one cat shed sporocysts but not the human volunteer. Electron microscopy of the cysts revealed many features that have not been described previously.