Sarcocystis masoni, n. sp. (Apicomplexa: Sarcocystidae), and redescription of Sarcocystis aucheniae from llama (Lama glama), guanaco (Lama guanicoe) and alpaca (Vicugna pacos)

SUMMARYThere is considerable confusion concerning the species of Sarcocystis in South American camelids (SAC). Several species names have been used; however, proper descriptions are lacking. In the present paper, we redescribe the macroscopic sarcocyst forming Sarcocystis aucheniae and describe and propose a new name, Sarcocystis masoni for the microscopic sarcocyst forming species. Muscles samples were obtained from llamas (Lama glama) and guanacos (Lama guanicoe) from Argentina and from alpacas (Vicugna pacos) and llamas from Peru. Individual sarcocysts were processed by optical and electron microscopy, and molecular studies. Microscopic sarcocysts of S. masoni were up to 800 µm long and 35–95 µm wide, the sarcocyst wall was 2·5–3·5 µm thick, and had conical to cylindrical villar protrusions (vp) with several microtubules. Each vp had 11 or more rows of knob-like projections. Seven 18S rRNA gene sequences obtained from sarcocysts revealed 95–96% identity with other Sarcocystis spp. sequences reported in the GenBank. Sarcocysts of S. aucheniae were macroscopic, up to 1·2 cm long and surrounded by a dense and laminar 50 µm thick secondary cyst wall. The sarcocyst wall was up to 10 µm thick, and had branched vp, appearing like cauliflower. Comparison of the 11 sequences obtained from individual macroscopic cysts evidenced a 98–99% of sequence homology with other S. aucheniae sequences. In conclusion, 2 morphologically and molecularly different Sarcocystis species, S. masoni (microscopic cysts) and S. aucheniae (macroscopic cysts), were identified affecting different SAC from Argentina and Peru.

Ultrastructure of Sarcocystis bertrami sarcocysts from a naturally infected donkey (Equus asinus) from Egypt

SUMMARYThere is considerable confusion concerning Sarcocystis species in equids. Little is known of Sarcocystis infections in donkeys (Equus asinus). Here we describe the structure of Sarcocystis bertrami-like from the donkey by light microscopy (LM) and transmission electron microscopy (TEM). Nineteen sarcocysts from the tongue of a donkey from Egypt were studied both by LM and TEM. By LM, all sarcocysts had variably shaped and sized projections on the sarcocyst walls, giving it a thin-walled to thick-walled appearance, depending on individual sarcocyst and plane of section. By TEM, sarcocysts walls had villar protrusions (vp) of type 11. The sarcocyst wall had conical to slender vp, up to 6 µm long and 1 µm wide; the vp were folded over the sarcocyst wall. The total thickness of the sarcocyst wall with ground substance layer (gs) was 1–3 µm. The vp had microtubules (mt) that originated deeper in the gs and continued up to the tip. The apical part of the vp had electron dense granules. The mt were configured into 3 types: a tuft of electron dense mt1 extending the entire length of the vp with a tuft of medium electron dense mt2 appearing in parallel, and fine mt3 present only in the villar tips. The gs was mainly smooth with few indistinct granules. All sarcocysts were mature and contained metrocytes and bradyzoites. Bradyzoites were approximately 11–15 × 2–3 µm in size with typical organelles.

A review of sarcocystosis in camels and redescription of Sarcocystis cameli and Sarcocystis ippeni sarcocysts from the one-humped camel (Camelus dromedarius)

SUMMARYThere is considerable confusion concerning Sarcocystis species in camels. Five species: Sarcocystis cameli, Sarcocystis ippeni, Sarcocystis camelicanis, Sarcocystis camelocanis and Sarcocystis miescheri were named with inadequate descriptions and no type specimens. Here, we review literature on sarcocystosis in camels worldwide and redescribe structure of S. cameli and S. ippeni sarcocysts by light- and transmission electron microscopy (LM and TEM). Eight sarcocysts from the oesophagi of two camels (Camelus dromedarius) from Egypt were studied. By LM, all sarcocysts were thin-walled with barely visible projections on the cyst walls. By TEM, two structurally distinct sarcocysts were recognized by unique villar protrusions (vp) not found in sarcocysts from any other host. Sarcocysts of S. cameli had vp of type 9j. The sarcocyst wall had upright slender vp, up to 3·0 µm long and 0·5 µm wide; the total thickness of the sarcocyst wall with ground substance (gs) layer was 3·5 µm. On each vp, there were rows of knob-like protrusions that appeared to be interconnected. The vp had microtubules that originated at midpoint of the gs and continued up to the tip; microtubules were smooth, without any granules or dense areas. Bradyzoites were approximately 14–15 × 3–4 µm in size with typical organelles. Sarcocystis ippeni sarcocysts had type 32 sarcocyst wall characterized by conical vp with an electron dense knob. The total thickness of the sarcocyst wall (from the base of gs to vp tip) was 2·3–3·0 µm. The vp were up to 1·2 µm wide at the base and 0·25 µm at the tip. Microtubules in vp originated at midpoint of gs and continued up to tip; microtubules were criss-crossed, smooth and without granules or dense areas. Bradyzoites were 12·0–13·5 × 2·0–3·0 µm in size. Sarcocystis camelicanis, S. camelocanis and S. miescheri are considered invalid.

Redescription of Sarcocystis fusiformis sarcocysts from the water buffalo (Bubalus bubalis)

SUMMARYFour valid species of Sarcocystis have been reported from the water buffalo (Bubalus bubalis): Sarcocystis fusiformis, Sarcocystis buffalonis, Sarcocystis levinei and Sarcocystis dubeyi. Here, we redescribe structure of S. fusiformis sarcocysts by scanning and transmission electron microscopy (SEM, TEM). Twenty-one macroscopic sarcocysts from oesophagus of the water buffalo in Egypt were examined by light microscopy, SEM and TEM. The sarcocyst wall was up to 9 μm thick, depending on the section and the technique. In 5 μm paraffin-embedded sections, the sarcocyst wall was indistinct, 2–5 μm thick and appeared smooth. In 1 μm plastic-embedded sections stained with toluidine blue, the sarcocyst wall was 2·5–5·2 μm thick and had branched villar protrusions (vp)-like branches of a dead tree. By SEM, the sarcocyst wall had a mesh-like structure with irregularly shaped vp that were folded over the sarcocyst wall. On each vp there were uniform papillomatous structures that were 100 nm wide. By TEM, vp were up to 6 μm long and contained filamentous tubular structures, most of which were parallel to the long axis of the projections; granules were absent from these tubules. By TEM, bradyzoites within the same cyst varied from 11·2 to 16·8 μm in length. By TEM, bradyzoites had a very long (10 μm) convoluted mitochondrion, up to 12 dense granules, but only 2 rhoptries. This redescription should help to differentiate the sarcocysts of S. fusiformis from similar sarcocysts in domestic and wild ruminants.

Chronic Polymyositis Associated with Disseminated Sarcocystosis in a Captive-born Rhesus Macaque

A 2–year-old, captive-born, clinically healthy male, rhesus macaque, was euthanatized as part of an experimental study. At necropsy, diffuse pale streaking of the trunk, lumbar, and limb muscles were noted macroscopically. On histology, numerous elongated cysts that contained crescent-shaped basophilic spores were found in the fibers of skeletal muscles. Scattered affected myofibers were degenerate and accompanied by eosinophilic-to-granulomatous inflammation. Sarcocysts had prominent villus-like projections with the morphology of a type 11 sarcocyst wall similar to Sarcocystis neurona but possessing many more villus microtubules than is reported for S. neurona. In addition, bradyzoites were very long, up to approximately 12 um in length. The protozoa were consistent with a Sarcocystis sp., based on histology and ultrastructure, however, a definitive identification of the species was not possible. Nonspecific immunohistochemical crossreaction with Sarcocystis cruzi antisera was observed. The 18S ribosomal deoxyribonucleic acid sequence showed 91% similarity to Sarcocystis hominis, 90% similarity to Sarcocystis buffalonis, and 89% similarity to Sarcocystis hirsuta. Interestingly, the ITSI sequence showed very little homology to any sequence in GenBank, suggesting that this is possibly a unique Sarcocystis sp. Sarcocystosis is often considered an incidental finding, particularly in wild-caught animals, with little clinical significance. However, as demonstrated in this report and others, disseminated sarcocystosis can occur in captive-born rhesus macaques with or without clinical signs. In some cases interference with research results can occur; including death in fulminant cases.

Morphologic and genetic characterization of Sarcocystis sp. from the African grey parrot, Psittacus erithacus, from Costa Rica

A species of Sarcocystis is reported from a naturally infected African grey parrot, Psittacus erithacus, from Costa Rica. Only mature sarcocysts, measuring up to 2 mm in length and up to 750 μm in width, were observed. The sarcocyst wall was smooth. The villar protrusions on the sarcocyst wall were up to 5 μm long and up to 1.1 μm wide; they were folded over the sarcocyst wall giving a thin-walled appearance. The microtubules in villar protrusions were smooth and confined to villar protrusions. Bradyzoites in sections were 5.4–6.6 × 1.3–2.0 μm in size. Sequencing the small subunit and first internal transcribed spacer portions of ribosomal DNA related this parasite to, but distinguished it from, previously characterized species of Sarcocystis that encyst in the musculature of birds and complete their sexual development in New World opossums of the genus Didelphis. This evidence suggests that the parrot may have acquired its infection from an opossum from which it suffered a debilitating attack a year prior to the onset of depression, anorexia, and ultimately death.

Morphologic characterization of Sarcocystis sp. sarcocysts from the Buffon’s macaw (Ara ambigua)

A species of Sarcocystis is reported from two naturally infected Buffon’s macaws (Ara ambigua) from Costa Rica. Only mature sarcocysts, measuring up to 950 μm in length and up to 75 μm in width, were observed. By light microscopy the sarcocyst wall was thin (< 1 μm thick) and smooth. The villar protrusions on the sarcocyst wall were up to 4.0 μm long and up to 0.6 μm wide; they were folded over the sarcocyst wall giving a thin-walled appearance. The microtubules in villar protrusions were smooth and confined to villar protrusions. Bradyzoites in sections were 4.0–5.9 × 0.8–1.8 μm in size. Structurally, sarcocysts from the macaw appeared different from sarcocysts of other avian species. This is the first report of Sarcocystis infection in this host.

Sarcocystis species in skeletal muscle of otter (Lutra lutra)

Cysts of a Sarcocystis species were found in large numbers in skeletal muscle of an otter (Lutra lutra) which was raised in Norway and died in captivity in Sweden. This is the first report of Sarcocystis infection in the otter. The sarcocysts were 0·3–2·3 mm long and 0·06–0·25 mm wide. As judged by light microscopy the sarcocyst walls were thin (<3 μm) with a serrated surface but without visible projections. By transmission electron microscopy, the sarcocyst wall measured 0·6–1·8 μm and had minute undulations covering the entire sarcocyst surface giving the wall a wavy appearance. Septa were indistinct. The sarcocysts contained few metrocytes and numerous bradyzoites. Sarcocysts were not found in 69 other otters subjected to necropsy in Sweden.

Development of Sarcocystis in mule deer transmitted through dogs and coyotes

Tissues from 13 experimentally inoculated mule deer (Odocoileus hemionus) from Oregon, studied by G. Hudkins and T. P. Kistner in 1976 and L. D. Koller, T. P. Kistner, and G. Hudkins in 1977, were reexamined. The following additional information on Sarcocystis hemionilatrantis was obtained. Two types of meronts were found in deer necropsied between 29 and 41 days postinoculation (DPI). Type 1 meronts were in capillaries in adrenal glands, kidney, lymph node, lung, choroid plexi, and spleen; meronts were 20.5 × 13.5 μm (14−32 × 10−20 μm; n = 26) and contained 20 to 35 nuclei. Type 2 meronts were found in macrophages in muscular tissues; these meronts were 20 × 14 μm (10−35 × 7−19 μm; n = 7) and contained 10 to 60 merozoites. Sarcocysts were seen in three deer at 63, 65, and 90 DPI. At 63 and 65 DPI sarcocysts were immature and their walls were thin (< 1 μm) and smooth. At 90 DPI, sarcocysts were up to 525 μm long and 50 μm wide; the sarcocyst wall was 1 to 2 μm thick and cross striated. In the same deer another type of mature sarcocyst was also seen; sarcocysts were up to 825 μm long, the walls were 2 to 4 μm thick and lacked cross striations. Two additional 3-day-old deer were inoculated orally with sporocysts from the feces of a dog fed meat from a mule deer from Montana naturally infected with Sarcocystis sp. Deer No. 1, fed 107 sporocysts, was killed at 14 DPI and deer No. 2, fed 5 × 106 sporocysts, was killed at 24 DPI. At 14 DPI, meronts were found in capillaries and arteries in the lung, heart, and spleen; the meronts were 26.5 × 20 μm (14−39 × 14−25 μm; n = 31) and contained up to 100 nuclei. At 24 DPI, intravascular meronts were found in the spinal cord, hepatic lymph node, kidney, thyroid gland, and mesenteric lymph node. In addition, meronts were found in macrophages in muscular tissues; these meronts were 16 × 10 μm (10−28 × 7−14 μm; n = 10) and contained up to 40 nuclei.

Sarcocystis peromysci n. sp. and S. idahoensis in deer mouse (Peromyscus maniculatus) in Montana

Two structurally distinct sarcocysts with thin and thick walls were found in 25 of 98 deer mice (Peromyscus maniculatus) in Montana. Thin-walled S. idahoensis sarcocysts were seen in 11 mice. Thick-walled sarcocysts were seen in 13 mice. A new name, S. peromysci, is proposed for the thick-walled sarcocysts. Sarcocystis peromysci sarcocysts were up to 1875 × 81 μm and contained 11.2 × 3.1 μm bradyzoites with prominent granules. The sarcocyst wall was 2–5.5 μm thick and had hairlike protrusions on its wall.