Sarcocystis neurona n. sp. (Protozoa: Apicomplexa), the etiologic agent of equine protozoal myeloencephalitis

Sarcocystis neuronan n. sp. is proposed for the apicomplexan taxon associated with myeloencephalitis in horses. Only asexual stages of this parasite presently are known, and they are found within neuronal cells and leukocytes of the brain and spinal cord. The parasite is located in the host cell cytoplasm, does not have a parasitophorous vacuole, and divides by endopolygeny. Schizonts are 5-35 microns x 5-20 microns and contain 4-40 merozoites arranged in a rosette around a prominent residual body. Merozoites are approximately 4 x 1 micron, have a central nucleus, and lack rhoptries. Schizonts and merozoites react with Sarcocystis cruzi antiserum but not with Caryospora bigenetica. Toxoplasma gondii, Hammondia hammondi, or Neospora caninum antisera in an immunohistochemical test.     

Ultrastructure of the cyst and life cycle of Sarcocystis sp. from wild sheep (Ovis musimon)

Sarcocystis sp. (Eimeriina: Sarcocystidae) is described as a heteroxenous coccidian with domestic dogs as an experimental definitive host and wild sheep (Ovis musimon) as natural intermediate hosts. Mature sarcocysts of this Sarcocystis sp. were examined by transmission electron microscopy. Sarcocysts in various muscle tissues were microscopic, had a thin primary cyst wall and septa and measured 81.0 x 30.5 microns. The cysts were located within muscle cells and were limited by a primary cyst wall (PCW). The cyst surface was highly folded forming densely packed projections. Between the PCW projections the surface of the cyst was marked with pit-like invaginations. The ground substance of the cyst formed a layer at the periphery of the cyst, filled the projections and formed septa which divided the cyst into compartments. Sarcocysts contained numerous bradyzoites that were 15.2 x 3 microns and few metrocytes 11.5 x 3.5 microns. Twelve days after ingesting Sarcocystis sp.-infected wild sheep meat, four dogs began passing sporocysts in their feces: two domestic cats did not pass oocysts or sporocysts after ingesting meat from the same animals. Sporocysts measured 14.8 x 9.9 microns.     

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 stenodactylicolubris n. sp., a new sarcosporidian coccidium with a snake-gecko heteroxenous life cycle

Oocysts/sporocysts of Sarcocystis sp. measuring 9.7 (9-10) x 7.6 (7-8) microns were found in the intestinal contents of the Dahl's whip snake Coluber najadum. Of wide spectrum of experimentally inoculated hosts, only species of the family Gekkonidae--Ptyodactylus guttatus and Stenodactylus grandiceps--were found to be susceptible intermediate hosts. Transparent, barely visible sarcocysts found in tail, limbs and tongue striated muscles of the geckoes were 175-200 microns x 35-50 microns in size at 78 DPI. Ultrastructurally, the primary cyst wall was characteristic by spine-like villar protrusions up to 800 nm long, 200-250 nm in diameter at their base, tapering to thinner apex. Protrusions appear typically lobular or irregular in the cross-sections. Back-transmission from P. guttatus to Coluber rogersi leaded to oocysts/sporocysts excretion since 38 days post infection. Based on sarcocyst morphology and experimental data, Sarcocystis stenodactylicolubris is apparently a new species. Based on obtained and already published results, Sarcosporidia parasitising colubrid snakes as definitive hosts are suggested to be family specific on the level of their intermediate host.     

Fatal perinatal sarcocystosis in a lamb

A 3-wk-old lamb died because of neurological disease. The predominant microscopic lesions were in the brain and spinal cord and consisted of nonsuppurative encephalomyelitis with severe gliosis throughout the gray and white matter. Immature and mature schizonts, 15.7 x 10.6 microns (8-30 x 6-18 microns), occurred in capillaries and were structurally similar to those of Sarcocystis tenella.     

Plasmodium kentropyxi n.sp. (Apicomplexa: Haemosporina: Plasmodiidae) and a Plasmodium tropiduri-like parasite in the lizard Kentropyx calcarata (Lacertilia: Teiidae) in north Brazil

Plasmodium kentropyxi n.sp. is described in the teiid lizard Kentropyx calcarata from north Brazil. Young asexual stages and gametocytes are at first polar in the erythrocyte but with elongation, move to a lateral position. Largest meronts seen contained from 30-40 nuclei and conspicuous greenish-black pigment granules located in a distinct vacuole. With growth the gametocytes eventually assume a smooth, curved cylindrical shape, with evenly rounded ends. Pigment is scattered or concentrated around a conspicuous vacuole which is slowly developed as the gametocytes mature. Mature male parasites measured 11.8 x 4.0 microns (9.6 x 4.2 - 13.2 x 3.6 microns), shape-index 2.9 (2.2 - 5.0), and females 13.5 x 4.5 microns (12.0 x 4.5 - 15.0 x 4.8 microns), shape-index 3.0 (2.2 - 3.8). Some larger meronts may slightly enlarge the erythrocyte, but most asexual stages and the mature gametocytes rarely do so. A second, P. tropiduri-like parasite encountered in K. calcarata possessed small rounded or fan-shaped meronts producing from 4-14 merozoites, and spherical to subspherical gametocytes of approximately 6.0 x 5.0 microns. The parasite was consistently polar in its position in the erythrocyte.     

Coccidia of Brazilian mammals: Eimeria marajoensis N. Sp. (Apicomplexa: Eimeriidae) from the Anteater, Tamandua tetradactyla (Xenarthra: Myrmecophagidae)

Feces from a juvenile specimen of the anteater Tamandua tetradactyla from Ponta de Pedras, Marajó, Pará, northern Brazil, contained three different coccidial oocysts: Eimeria tamanduae Lainson, 1968; E. corticulata Lainson & Shaw, 1990; and a third species previously unrecorded and described here as Eimeria marajoensis n. sp. Oocysts of the latter parasite are spherical to subspherical, 13.9 +/- 1.5 x 13.4 +/- 1.4 (11.1-16.5 x 11.1-16.5) microns, shape index (length/width) 1.0 (1.0-1.2). The oocyst wall is a single, colorless layer about 0.6-1.0 microns thick with no striations or micropyle. There is no oocyst residuum, but a single, round, oval or irregularly shaped polar granule of about 0.75-2.5 microns is consistently present. The sporocysts are broadly ellipsoidal, 7.1 +/- 0.7 +/- 5.3 +/- 0.6 (6.0-8.8 x 4.0-5.7) microns, shape index 1.3 (1.2-1.5), with a delicate wall bearing minute stieda body. No sub-stieda body was visible. The sporocyst residuum consists of some 10-20 rounded granules, lying between the two slightly curved sporozoites which measure approximately 6.5 x 2.0 microns. Sporocyst refractile bodies were not discernable.     

Sarcocystis speeri N. sp. (Protozoa: Sarcocystidae) from the opossum (Didelphis virginiana)

The North American opossum (Didelphis virginiana) is host to at least 3 species of Sarcocystis: Sarcocystisfalcatula, Sarcocystis neurona, and a recently recognized Sarcocystis sp. A new name, Sarcocystis speeri, is proposed for the third unnamed Sarcocystis. Immunodeficient mice are an experimental intermediate host for S. speeri. Sarcocystis speeri sporocysts are 12-15 x 8-10 microm in size, and its schizonts are found in many organs of mice. Sarcocysts of S. speeri are found in skeletal muscles and they are up to 5 mm long and filiform. By light microscopy, the sarcocyst wall is thin (<1 microm thick); ultrastructurally, the cyst wall is up to 1.8 microm thick and has characteristic steeple-shaped villar protrusions surmounted by a spire. Sarcocystis speeri schizonts are morphologically and antigenically distinct from schizonts of S. neurona, and S. speeri sporocysts were not infective to budgerigars (Melopsittacus undulatus).     

Enzyme variation of Eimeria arizonensis from Peromyscus truei and P. boylii

Cricetid rodents, Peromyscus truei and P. boylii, were inoculated with sporulated oocysts of Eimeria arizonensis collected from wild P. truei maintained in the lab. In P. truei the prepatent period was 4-5 days, the patent period was 9-11 days, and sporulated oocysts were 21.5 x 25.0 (20-23 x 24-26) microns with sporocysts 7.7 x 12.0 (6-8 x 10-13) microns. In P. boylii the prepatent period was 6-7 days, the patent period was 8-9 days, and sporulated oocysts were 20.1 x 23.2 (18-22 x 21-24) microns with sporocysts 6.8 x 10.0 (5-8 x 9-12) microns. Sporulated oocysts from both host species were used in direct side-by-side comparison of isozyme banding patterns using protein electrophoresis. The parasite has polytypic loci for leucine aminopeptidase (LAP), lactate dehydrogenase (LDH), and 6-phosphogluconate dehydrogenase (6-PGD). In oocysts from P. truei, LAP showed one band with fast migration and LDH and 6-PGD each showed two bands, one with fast and one with slow migration. In oocysts from P. boylii, LAP and LDH each had one band with slow migration and 6-PGD had one band with moderate migration. Oocysts of E. arizonensis collected from P. boylii were used to inoculate P. truei. The prepatent and patent periods, structural measurements, and isozyme banding patterns of the resultant oocysts were the same as those from P. truei when inoculated with oocysts from P. truei.     

Eimeria cryptotis n. sp. (Apicomplexa: Eimeriidae) from the least shrew, Cryptotis parva (Insectivora: Soricidae), in north-central Texas

From March through November 1987, 14 least shrews, Cryptotis parva (Say), were collected in portions of north-central Texas and examined for coccidian parasites; only 1 (7.1%) was found to be passing oocysts. Eimeria cryptotis n. sp. is described herein as new and represents the only coccidian reported thus far from C. parva. Sporulated oocysts are subspherical, 16.4 x 15.3 (14-18 x 13-17) microns; shape index 1.1 (1.0-1.2) microns. A micropyle and oocyst residuum are absent, but a polar granule is present. The sporocysts are ovoid, 10.6 x 7.0 (9-11 x 6-8) microns; shape index 1.5 (1.4-1.8) microns. Stieda and substieda bodies and a sporocyst residuum are present. The sporozoites are elongate and only 2 could be observed well enough to measure (11.2 x 2.4 and 8.8 x 2.4 microns) because they are normally obscured by the sporocyst residuum. Sporozoites lack refractile bodies and contain a centrally located nucleus. The new species can be distinguished from the majority of insectivore coccidia on the basis of oocyst size.     

Sarcocystis lindsayi n. sp. (Protozoa: Sarcocystidae) from the South American opossum, Didelphis albiventris from Brazil

A new species, Sarcocystis lindsayi n. sp., is proposed for a parasite resembling Sarcocystis falcatula. It was obtained from the lungs and muscles of budgerigars (Melopsittacus undulatus) fed sporocysts from a naturally-infected South American opossum, Didelphis albiventris, from Jaboticabal, Brazil. Sarcocysts of S. lindsayi n. sp. in budgerigars are microscopic, up to 600 microm long and up to 50 microm wide. The cyst wall is up to 2 microm thick. Ultrastructurally, the sarcocyst wall consists of numerous slender villar protrusions (up to 2.0 microm long and up to 0.3 microm wide), each with a stylet at its tip. Schizonts in cell culture divide by endopolygeny leaving a residual body. Sporocysts are approximately 12 x 7 microm. The parasite is genetically distinct from other organisms that also cycle between opossums and avian species and resemble S. falcatula. Diagnostic genetic variation has been observed in the nuclear large subunit ribosomal RNA gene, the internal transcribed spacer (ITS-1), and each of two other genetic loci. Although the structure of the sarcocyst wall may not provide sufficient grounds for differential diagnosis, several other attributes including schizont morphology and genetic variation at each of these genetic loci permit identification of S. lindsayi n. sp.. Natural intermediate hosts for S. lindsayi n. sp. are not known, and fuller characterization of these and other Sarcocystis species would benefit from experimental avian hosts that are more permissive to the maturation of sarcocysts.     

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 infections among snakes in Israel

Natural infection with Sarcocystis has been recovered from 11 species of snakes from Israel and the adjacent territories (Cisjordan), infection was most abundant in subadults. Sporocyst dimensions obtained from the different snakes overlapped in size, but even in a same host species formed distinct size cohorts clustering either around 8.5 x 6.5 microns and 11.0 x 8.5 microns or around 11.0 x 8.5 microns and 12 x 10 microns. Sporocyst-size distribution was, however, altered following cross infections or in consecutively emitted feces. The largest cohort size conformed with the sporocyst dimensions of S. murivipera Matuscka, Heydorn, Mehlhorn, Abd-Al-Az, Diesing, Bichler 1987, described from Vipera palaestinae, one of the snake species included in the present study. Among infected snakes were rodent predators but also species feeding on smaller prey (reptiles). Sporocysts from eight of these species including some small-prey feeders, were available for infecting rodents, all, like S. murivipera, developed into sarcocysts in laboratory white mice (Mus musculus), but in none of the inoculated rodents from other genera, or reptiles. Sarcocysts found in free-ranging house mice infected V. palaestinae. Despite of an apparent conspecificity, Sarcocystis from the different snake species demonstrated a pronounced variation in their virulence to mice. Primary wall was identical in all ultrastructurally studied sarcocysts found in both house mice and laboratory mice fed on sporocysts from the diverse snake species.     

Haematozoa of fishes in Humboldt Bay, California.

Five hundred seven fish representing 45 species from Humboldt Bay, California (USA) were examined for blood parasites. Four fish (less than 1%) from two species were infected. Haemogregarina leptocotti sp. n. is described from one of 33 staghorn sculpin (Leptocottus armatus). Haemogregarina roelofsi sp. n. is described from three of 15 black rockfish (Sebastes melanops). Gametocytes of H. leptocotti sp. n. averaged 6.1 x 2.1 microns with a 2.7 x 1.7 microns oval nucleus; those of H. roelofsi sp. n. averaged 5.5 x 2.7 microns with a 2.5 x 2.2 microns rectangular nucleus. Neither species of parasite had distinct chromatin granules, a polar cap, or more than one gametocyte in an infected cell. Haematozoa are relatively rare in fishes of the northeastern Pacific Ocean.     

Description of the oocysts of Eimeria paludosa (Apicomplexa: Eimeriidae) from Fulica americana (Aves: Gruiformes), with comments on synonyms of eimerian species from related birds

Between November and December 1988, fecal and intestinal contents were collected from 25 northern American coots, Fulica americana americana, in Arkansas and Texas, and examined for coccidial parasites. Seventeen (68%) of the coots were infected with Eimeria paludosa, herein described; for the first time, photomicrographs of the species are presented. Sporulated oocysts are ovoid, 16.5 x 12.6 (15-23 x 11-14) microns, with a lightly to heavily pitted single-layered wall; an oocyst residuum is absent, but a prominent micropyle is present. A large, or several smaller, polar granule(s) is present, usually located beneath the micropyle. Sporocysts are elongate-ovoid, 10.8 x 6.2 (10-12 x 5-7) microns, with Stieda and substieda bodies. A sporocyst residuum is present, normally composed of very fine faint granules scattered among the sporozoites or, rarely, as a spherical mass. Sporozoites are elongate, 8.7 x 2.7 (7-11 x 2-3) microns, in situ. Each sporozoite contains a spherical-ellipsoid posterior refractile body and occasionally a spherical anterior refractile body. A nucleus is located immediately anterior to the posterior refractile body. The occurrence of E. paludosa in F. a. americana is a new host and geographic record for the parasite. In addition, several of the previously described eimerian species from gruiform birds are proposed to be synonyms of E. paludosa.     

Three new species of Eimeria (Apicomplexa: Eimeriidae) from Apalone spinifera pallidus (Testudines: Trionychidae) in Texas, with a redescription of E. amydae

Three new species of Eimeria are described from pallid spiny softshells, Apalone spinifera pallidus, collected in north-central Texas. Oocysts of Eimeria spinifera n. sp. were found in the feces of 3/9 (33%) turtles and are subspheroid, ellipsoid, or pear-shaped, 16.3 x 14.0 (14-19 x 12-18) microns, with a thin, single-layered wall; shape index 1.2 (1.1-1.3). A micropyle is absent, but an oocyst residuum is present; polar granule present in 16% of the oocysts. Sporocysts are elongate-ovoid, 10.3 x 5.2 (8-12 x 5-6) microns, each with a Stieda body bearing short filaments. Oocysts of Eimeria apalone n. sp. were found in 5/9 (56%) turtles and are ellipsoid, elongate pear-shaped, or subspheroid, 16.8 x 13.2 (12-19 x 10-16) microns, with a thin, single-layered wall; shape index 1.3 (1.0-1.5). A micropyle, oocyst residuum, and polar granule are absent. Sporocysts are elongate-ovoid, 11.3 x 6.2 (9-14 x 5-7) microns, each with a prominent Stieda body. Oocysts of Eimeria pallidus n. sp. were found in 4/9 (44%) A. s. pallidus and are spheroid or subspheroid, 23.4 x 21.6 (18-27 x 17-25) microns, with a thin, single-layered wall; shape index 1.1 (1.0-1.3). A micropyle is absent, but an oocyst residuum is present; polar granule present in 20% of the oocysts. Sporocysts are elongate-ovoid, 14.3 x 6.2 (13-17 x 6-7) microns, each with a Stieda body and short filaments. In addition to the new species, 3 previously described eimerians, including Eimeria amydae Roudabush, 1937, which is redescribed, were also found.     

Garnia karyolytica n. sp. (Apicomplexa: Haemosporina: Garniidae), a blood parasite of the Brazilian lizard Thecodactylus rapicaudus (Squamata: Gekkonidae).

Development of meronts and gametocytes of Garnia karyolytica nov. sp., is described in erythrocytes of the neotropical forest gecko Thecodactylus rapicaudus from Pará State, north Brazil. Meronts are round to subspherical and predominantly polar in position: forms reaching 12.0 x 10.0 microns contain from 20-28 nuclei. Macrogametocytes and microgametocytes are predominantly elongate, lateral in the erythrocyte and average 16.6 x 6.3 microns and 15.25 x 6.24 microns respectively. Occasional spherical forms of both sexes occur in a polar or lateropolar position. All stages of development are devoid of malarial pigment. They have a progressively lytic effect on the host-cell nucleus, particularly the mature gametocytes, which enlarge and deform the erythrocyte. Possible vector(s) of garniid parasites are considered, and phlebotomine sandflies are high on the list of suspects.     

Isospora daphnensis n. sp. (Apicomplexa: Eimeriidae) from the medium ground finch (Geospiza fortis) from the Galapagos Islands

In March and April 1987 fecal samples from 237 nestling birds, including 199 from 85 nest sites of Geospiza fortis, 23 from 12 nest sites of Geospiza scandens, 6 from 2 nest sites of Geospiza magnirostris, and 9 from 2 nest sites of hybrids involving Geospiza fuliginosa and G. fortis, were collected from Daphne Major in the Galapagos archipelago and examined for coccidia. Only 3 of 4 nestlings from 1 nest site of G. fortis (1.5%) had oocysts in their feces. Two of the 3 infected nestlings had concurrent infections of Isospora temeraria, and all 3 nestlings were infected with a new species. Isospora daphnensis n. sp. Sporulated oocysts of I. daphnensis n. sp. are ellipsoidal, 27.3 x 23.6 (22-30 x 20-27) microns; a polar body is present, but no oocyst residuum or micropyle occurs. The oocyst wall, approximately 1.5 microns thick, is composed of a mammillated outer layer and thinner inner layer. Sporocysts are ovoid, 15.2 x 10.2 (15-16 x 9-11) microns and have a nipplelike Stieda body and a small substieda body. The sporocysts contain an irregularly shaped, smoothly contoured residuum with uniform granules and 4 sporozoites with a large refractile body at one end and lying randomly in the sporocysts.