Sarcocyst Wall Research Articles

Muscular Sarcocystis Infection in a Bear (Ursus americanus)

Sarcocysts of an unidentified Sarcocystis species were found in sections of skeletal muscles of a black bear (Ursus americanus) from North Carolina. Two sarcocysts in a section measured 45 x 37.5 microm and 67.5 x 50 microm and had a thin (<2 microm) sarcocyst wall. The villar protrusions on the cyst wall were up to 2 microm long and up to 0.7 microm wide. The bradyzoites were approximately 6 X 2.5 microm in size. This is the first report of muscular Sarcocystis in a bear.

Sarcocystis dubeyella n. sp. and Sarcocystis phacochoeri n. sp. (Protozoa: Sarcocystidae) from the warthog (Phacochoerus aethiopicus) in South Africa.

Sarcocystis dubeyella n. sp. and S. phacochoeri n. sp. from muscle fibers of the skeletal musculature of two warthogs in South Africa are described by light and and electron microscopy. Sarcocystis dubeyella sarcocysts are macroscopic (up to 12 mm long and 1 mm wide), with a parasite-induced encapsulation of the host muscle fiber in which the plasma membrane of the latter remained unaltered. The sarcocyst wall is characterized by evenly arranged, irregularly semicircular or rectangular villar protrusions (5.0 x 2.8-11.0 microns) with indented margins and no specific content. Sarcocystis phacochoeri formed filiform microcysts (up to 4 mm long and 0.13 mm wide). Its cyst wall is provided with tightly packed, molarlike villar protrusions (1.6-3.3 x 1.7-3.3 microns), with smooth margins, hollow on one side, and with longitudinal condensations of the fine granular matrix at various locations in the interior.

Sarcocystosis in Mink (Mustela vison)

This report describes the clinical, microscopic, and ultrastructural findings in mink with muscular sarcocystosis. Three 2-3-mo-old mink were killed because they were ill with signs of progressive neurological disease. One mink had variable numbers of sarcocysts in multiple skeletal muscles. Sarcocysts were up to 300 microm in long and 20 microm wide. Ultrastructurally, the sarcocyst wall had numerous elongated 1.7-2.0-microm x 250-nm villar protrusions (VP). The VP had microtubules and irregularly distanced minute undulations. Both metrocytes and bradyzoites were present in sarcocysts. The mink with sarcocysts in muscles also had nonsuppurative meningoencephalitis and meningomyelitis. Similar brain lesions were found in other 2 mink from the same farm, but sarcocysts were not observed in the skeletal muscle of these animals. This is the first report of muscular sarcocystosis in mink.

Prevalence of Sarcocystis in domestic pigs in India

Muscle samples from 890 slaughtered pigs were examined for the presence of sarcocysts. A high prevalence rate of 67.98% was observed. Two types of microsarcocysts were recorded. The sarcocyst wall of one type had redial striations and the other possessed hair-like villar protrusions. The species were identified as Sarcocystis miescheriana and Sarcocystis suihominis; there was a slightly higher incidence of the latter species (47.11%) than of the former (43.14%). S. suihominis has been identified for the first time from pigs in India.

Sarcocystis kirkpatricki n. sp. (Apicomplexa: Sarcocystidae) in Muscles of Raccoons (Procyon lotor) from Illinois

Sarcocysts of Sarcocystis kirkpatricki n. sp. (Apicomplexa: Sarcocystidae) are described from the skeletal and heart musculature of 66 (66%) of 100 raccoons (Procyon lotor) from Illinois. Histologic examination of muscle tissues from tongue, diaphragm, esophagus, and heart revealed that 61%, 47%, 32%, and 2%, respectively, contained sarcocysts of this species. Juvenile raccoons (less than 1 yr old) were more likely (P less than 0.01) to have sarcocysts in the tissues examined (52/60 or 87%) than were adults (14/40 or 35%). Histologically, sarcocysts in the 4 tissues were similar: the cyst wall was 2-3 microns thick, PAS negative, and had fine hairlike surface projections; interior septa were indistinct. Ultrastructurally, sarcocyst walls had short (mean = 2.8 microns), straight to sloping, villuslike projections. Longitudinal tubular filaments inside these projections extended from the tips to the base, where they terminated in a granular electron-dense layer of the primary cyst wall. Thin septa were within the sarcocysts. Feeding experiments utilizing dogs and cats as potential definitive hosts were negative.

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.

Sarcocystis sigmodontis n. sp. from the Cotton Rat (Sigmodon hispidus)

Sarcocystis sarcocysts were found in 3 of 4 cotton rats (Sigmodon hispidus) from Atlanta, Georgia. Sarcocysts were several centimetres long and were present only in skeletal muscles. The sarcocyst wall appeared thin (less than 1 micron), with minute projections in the light microscope. By transmission electron microscopy, the sarcocyst wall had 0.6-1.0 x 0.21-0.36-micron villar protrusions without microtubules. The metrocytes were 6.5 x 3.8 micron, and the bradyzoites were 8 x 2.7 micron. The sarcocysts were not infectious for dogs and cats. The parasite was named Sarcocystis sigmodontis because it differed from all sarcocysts in rodents.

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.

Experimental transmission of Sarcocystis muriviperae n. sp. to laboratory mice by sporocysts from the Palestinian viper (Vipera palaestinae): a light and electron microscope study.

Sporocysts collected from the feces of a Palestinian viper (Vipera palaestinae) were administered orally to species of various rodent genera such as Mus, Microtus, Mastomys, Meriones and Oryctolagus. Infections developed only in laboratory mice (Mus musculus). This investigation established the life cycle of Sarcocystis muriviperae in the laboratory. S. muriviperae is described as a new species, based on light and electron microscopic observations and repeated transmission studies. Naturally and experimentally infected Palestinian vipers both excreted structurally identical sporocysts measuring 9.6 micron (8.8-10.5 microns) by 12.2 microns (11.7-12.9 microns). Sporulation inside the snakes' intestine is completed between 14 and 19 days post-inoculation (p.i.). Rosette-like schizogonic stages were found in the liver cells of laboratory mice 9-10 days after infection with sporulated sporocysts. Sarcocysts measured up to 1,000 microns in length on day 36 p.i. and were mainly filled with metrocytes. The septated sarcocysts found 136 or 165 days p.i. reached a length of 5-8 mm and a width of 150-400 microns. The primary sarcocyst wall formed cauliflower-like branched protrusions about 3.5 microns in length.

The Taxonomy of Sarcocystis (Protozoa, Apicomplexa) Species

The taxonomy of the heteroxenous apicomplexan protozoan genus Sarcocystis was reviewed, and a list of 122 species with their synonyms and hosts given. Both definitive and intermediate hosts are known for only 56 species. The fine structure of the sarcocyst wall may change with age and is not considered necessarily satisfactory for separating species. Specificity for the intermediate host is not narrow for all species. Earlier work on transmission of the parasite from one intermediate host to another should be repeated in the light of present knowledge of the life cycle of species of Sarcocystis.

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 (&lt; 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.

The ultrastructure of the cyst wall of a murine Sarcocystis.

Electron microscope studies of the cyst wall of a murine Sarcocystis-like organism of Mus musculus indicate that the sarcocyst wall is a degenerate muscle cell. The degenerate muscle cell contains nuclei, mitochondria, ribosomes, and myofibrils in disarray with the A-bands thickened. Surrounding the outside of the muscle cell there is a layer of fibrous material, and occasional fibroblasts are seen. The parasites are found within a parasitophorous vacuole in the muscle cell. There are short-finger-like projections extending into the vacuole from the muscle cell. The ground substance of the vacuole is fairly homogeneous, but somewhat more electron dense between the finger-like projections.