Early development of Eimeria papillata (Apicomplexa: Eimeriidae) in the mouse

Early development of Eimeria papillata (Apicomplexa) in the mouse was evaluated using Nomarski interference-contrast and brightfield microscopy. Sporozoite-shaped meronts, which were motile and contained a large posterior refractile body and a smaller anterior refractile body, were observed entering and leaving host cells in the jejunum of an experimentally infected mouse at 26 h post inoculation (HPI). However, early developmental stages were not observed in tissue of the duodenum, ileum, cecum and colon. The mean length and width of these meronts (n = 20) were 12.0 microns and 3.7 microns, respectively. Spherical or subspherical meronts containing crescent-shaped merozoites were observed at 36 HPI.     

Life Cycle of Isospora rivolta (Grassi, 1879) in Cats and Mice*

SYNOPSIS. The endogenous development of Isospora rivolta (Grassi) was studied in cats fed oocysts, and was compared with the endogenous cycle after feeding them mice infected with I. rivolta. For the mouse-induced cycle, 14 newborn cats were killed 12 to 240 h after having been fed mesenteric lymph nodes and spleens of mice. Asexual and sexual development occurred throughout the small intestine, in epithelial cells of the villi and glands of Lieberkuhn. The number of asexual generations was not determined with certainty, but there were at least 3 structurally different meronts. Type I meronts appeared at 12–48 h postinoculation (HPI). They were 8.5(6–13) × 5.1(3–6) μm, contained 2–8 merozoites, and divide by binary division or endodyogeny. Type II meronts were multinucleate merozoite-shaped meronts within a single parasitophorous vacuole. They were found at 48–172 HPI and measured 12.6(9–18) × 9.8(9–13) μm. Individual multinucleate merozoite-shaped meronts were 7–13 × 3–5 μm in sections and contained 2–30 slender (5.5 × 1.0 μm) merozoites. Type III meronts occurred at 72–192 HPI and gamonts at 72–96 HPI. Mature microgamonts measured 11.3(9–15) × 8.0(6–9) μm in sections and up to 21.5 × 14 μm in smears, and contained up to 70 microgametes. Macrogamonts measured 13.3(11–18) × 9.0(5–13) μm in sections and 18 × 16 μm in smears. Oocysts were 10–15 × 9–15 μm in sections and 19.8(17–24) × 18.0(17–23) μm in fixed and stained smears. Unsporulated oocysts in feces were 22.3(18–25) × 19.7(16–23) μm and spomlated oocysts 25.4(23–29) × 23.4(20–26) μm. Sporulation was completed within 24 h at 22–26 C. For the study of the oocyst-induced cycle in cats, 18 newborn cats were killed between 6 and 192 HPI. The endogenous development was essentially similar to the mouse-induced cycle, but merogony and gametogony occurred 12–48 h later than in the latter cycle. Isospora rivolta was pathogenic for newborn but not for weaned cats. Newborn cats fed 10⁵ sporocysts or infected mice usually developed diarrhea 3–4 days after inoculation. Microscopically, desquamation of the tips of the villi and cryptitis were seen in the ilium and cecum in association with meronts and gamonts. For the study of the development of I. rivolta in mice, mice were killed from day 1 to 23 months after having been fed 10⁵–10⁵ sporocysts, and their tissues were examined for the parasites microscopically, and by feeding to cats. The following conclusions were drawn. (A) Isospora rivolta most frequently invaded the mesenteric lymph nodes of mice and remained there for 23 months at least. It also invaded the spleen, liver, and skeletal muscles of mice. This species could not be passed from mouse to mouse. Sporozoites increased in size from ?6.8 × 4.9 μm on day 1 to ?13.4 × 6.9 μm on day 31 postinoculation. Division was not seen. Prepatent period was 4–7 days and patent periods ranged from 2 to several weeks.     

New Observations on First-Generation Merogony of Eimeria tuskegeensis in Sigmodon hispidus1

First-generation development of Eimeria tuskegeensis was evaluated using light microscopy. Sporozoite-shaped meronts containing a prominent refractile body were observed in small intestinal cells of an experimentally infected cotton rat at 24 h post inoculation (PI). Mature spherical or subspherical meronts containing crescent-shaped merozoites were observed at 36 h PI. Refractile bodies were observed in some of these merozoites. Sporozoite-shaped meronts that were isolated from host intestinal cells and inoculated onto human fetal lung cell cultures penetrated the cultured cells by 2 h PI. A mature, subspherical, first-generation meront containing seven merozoites was observed at 9 h PI in cell culture, indicating that sporozoite-shaped meronts isolated from the host retained their infectivity.     

New observations on first-generation merogony of Eimeria tuskegeensis in Sigmodon hispidus

First-generation development of Eimeria tuskegeensis was evaluated using light microscopy. Sporozoite-shaped meronts containing a prominent refractile body were observed in small intestinal cells of an experimentally infected cotton rat at 24 h post inoculation (PI). Mature spherical or subspherical meronts containing crescent-shaped merozoites were observed at 36 h PI. Refractile bodies were observed in some of these merozoites. Sporozoite-shaped meronts that were isolated from host intestinal cells and inoculated onto human fetal lung cell cultures penetrated the cultured cells by 2 h PI. A mature, subspherical, first-generation meront containing seven merozoites was observed at 9 h PI in cell culture, indicating that sporozoite-shaped meronts isolated from the host retained their infectivity.     

Coccidian Parasites (Apicomplexa: Eimeriidae) of Nerodia spp. (Serpentes: Colubridae), with a Description of a New Species of Eimeria

Eimeria conanli n. sp. (Apicomplexa: Eimeriidae) is described from intestinal contents and feces of Nerodia erythrogaster transversa and N harteri harteri from northcentral Texas. Oocysts of the new species are ellipsoid in shape. 17.9 × 13.0(15–21 × 12–15) μm, with a smooth, thin, single-layered wall; shape index 1.4 (1.2–1.5). One to several (usually 2) polar granule(s) and an oocyst residuum are present, but a micropyie is absent. Sporocysts are elongate, 12.9 × 5.2 (13–15 × 5–6) -m, apparently without a true Stieda body structure. Each sporoeyst contains an ellipsoid residuum, 3.9 × 3.2 (3–6 × 2–4) μm, and elongate sporozoites, 11.4 × 2.5 (10–14 × 2–3) μm in situ, each with a spherical or subspherical anterior refractile body and spherical to ellipsoid posterior refractile body. In addition to the new species, oocysts of 4 previously described eimerians from colubrid snakes were found in these hosts.     

The Structure of the Oocyst and the Excystation Process of Isospora marquardti sp. n. from the Colorado pika, Ochotona princeps

SYNOPSIS. Oocysts of Isospora marquardti sp. n. from the Colorado pika, Ochotona princeps , have spheroid oocysts, 30.5 (23–36) μm in diameter, and ovoid sporocysts, measuring 19.3 × 12.0 (17–22 × 10–14) μm. A polar body, 2 × 4 μm, a spheroid sporocyst residuum (8.3 μm in diameter), a Stieda body, and a distinct substiedal body (3 × 3 μm) are present. A micropyle and an oocyst residuum are absent. Excysted sporozoites, averaging 3.0 × 18.5 (2–4 × 15–20) μm, contain 2 refractile globules, 1 on each side of the nucleus with a prominent nucleolus.
The sporozoite excystation process using a trypsin-sodium taurocholate fluid is described.     

Wenyonella baghdadensis sp. n. from the Bandicoot Rat Nesokia indica in the Baghdad Area

SYNOPSIS. Oocysts of Wenyonella baghdadensis sp. n. were found in the feces of 2 of 12 bandicoot rats Nesokia indica Gray & Hardwicke from the Baghdad area. Sporulated oocysts were subspherical to broadly ellipsoidal, 25.4 (18–22) × 20.8 (15–28) μm, with a 2-layered wall, the outer wall being mammillated, without micropyle, micropylar cap, residuum, or polar granule. Sporozoites were ovoid, 11.8 (9–15) × 8.4 (6–10) μm, with Stieda body and residuum. Two sporozoites in each sporocyst were elongate, with granular cytoplasm and a refractile globule, the other 2 were bean-shaped, without granules or refractile globule. Sporulation time equalled 3 days at 22–24 C. Entamoeba coli and Giardia sp. cysts were also found in 3 rats each.     

Eimeria saudiensis N. Sp. (Apicomplexa: Eimeriidae) from the Arabian Oryx (Oryx leucoryx) in Saudi Arabia

Oocysts of Eimeria saudiensis n. sp. (Apicomplexa: Eimeriidae) are described from the feces of the Arabian oryx, Oryx leucoryx , from the Riyadh Zoo, Saudi Arabia. The oocysts were ellipsoidal or slightly ovoid, 31.2 times 24.5 (24.3–36.5 times 20.0–27.6) μm with a bilayered wall about 1.7 μm thick. The micropyle was covered by a dome-shaped cap. The oocyst residuum was absent, but tiny polar granules were present. The sporocysts were elongate ovoid, 14.3 times 7.2 (11.5–18.5 times 6.0–9.0) μm, had a Stieda body, but lacked a substiedal body. The sporocyst residuum was present, composed of numerous small granules. The sporozoites were elongate club-shaped, and contained two prominent refractile bodies.     

Life cycle of Isospora rivolta (Grassi, 1879) in cats and mice

The endogenous development of Isospora rivolta (Grassi) was studied in cats fed oocysts, and was compared with the endogenous cycle after feeding them mice infected with I. rivolta. For the mouse-induced cycle, 14 newborn cats were killed 12 to 240 h after having been fed mesenteric lymph nodes and spleens ofmice. Asexual and sexual development occurred throughout the small intestine, in epithelial cells of the villi and glands of Lieberkühn. The number of asexual generations was not determined with certainty, but there were at least 3 structurally different meronts. Type I meronts appeared at 12-48 h postinoculation (HPT). They were 8.5(6-13) x 5.1(3-6) micrometer, contained 2-8 merozoites, and divide by binary division or endodyogeny. Type II meronts were multinucleate merozoite-shaped meronts within a single parasitophorous vacuole. They were found at 48-172 HPI and measured 12.6(9-18) x 9.8(9-13) micrometer. Individual multinucleate merozoite-shaped meronts were 7-13 x 3-5 micrometer in sections and contained 2-30 slender (5.5 x 1.0 micrometer) merozoites. Type III meronts occurred at 72-192 HPI and gamonts at 72-96 HPI. Mature microgamonts measured 11.3(9-15) x 8.0(6-9) micrometer in sections and up to 21.5 x 14 micrometer in smears, and contained up to 70 microgametes. Macrogamonts measured 13.3(11-18) x 9.0(5-13) micrometer in sections and 18 x 16 micrometer in smears, and contained up to 70 microgametes. Macrogamonts measured 13.3(11-18) x 9.0(5-13) micrometer. Sporulation was completed within 24 h at 22-26 C. For the study of the oocyst-induced cycle in cats, 18 newborn cats were killed between 6 and 192 HPI. The endogenous development was essentially similar to the mouse-induced cycle, but merogony and gametogony occurred 12-48 h later than in the latter cycle. Isospora rivolta was pathogenic for newborn but not for weaned cats. Newborn cats fed 10(6) sporocysts or infected mice usually developed diarrhea 3-4 days after inoculation. Microscopically, desquamation of the tips of the villi and cryptitis were seen in the ilium and cecum in association with meronts and gamonts. For the study of the development of I. rivolta in mice, mice were killed from day 1 to 23 months after having been fed 10(5)-10(6) sporocysts, and their tissues were examined for the parasites microscopically, and by feeding to cats. The following conclusions were drawn. (A) Isospora rivolta most freqeuntly invaded the mesenteric lymph nodes ofmice and remained there for 23 months at least. Ii also invaded the spleen, liver, and skeletal muscles of mice. This species could not be passed from mouse to mouse. Sporozoites increased in size from approximately 6.8 x 4.9 micrometer on day 1 to approximately 13.4 x 6.9 micrometer on day 31 postinoculation. Division was not seen. Prepatent period was 4-7 days and patent periods ranged from 2 to several weeks.     

The morphology and development of Nosema carpocapsae,a microsporidian pathogen of the codling moth,Cydia pomonella (Lepidoptera: Tortricidae) in New Zealand

The morphology of Nosema carpocapsae and its development in experimentally infected codling moth larvae are described. Spherical uninucleate meronts were the first stages. Nuclear division produced binucleate meronts which were the most abundant vegetative stage, although additional uninucleate and a few tetranucleate meronts were also observed at this time. All meronts were spherical and ranged from 2.8 to 5.8 μm in diameter. Uninucleate and binucleate fusiform sporonts then appeared followed by some tetranucleate and dividing forms. Oval sporoblasts developed after these and did not divide before maturing into spores. Sporonts were approximately 5.0 to 7.9 × 2.4 to 3.0 μm. Spores developed in all host tissues except the nervous tissue. The binucleate spores showed considerable variation in spore size, 2.4 to 3.9 × 1.3 to 3.1 μm (alcohol fixed, Giemsa stained). The polar filament was usually coiled 11 times (range 9 to 13) at an angle of 53° to the long axis of the spore. Its maximum observed length was 75 μm.     

Description of the Oocysts of Two New Species of Eimeria (Apicomplexa: Eimerüdae) from the Florida Manatee, Trichechus manatus (Sirenia: Trichechidae)

Two new species of Eimeria (Apicomplexa: Eimerüdae) are described from the feces of the Florida manatee, Trichechus manatus latirostrts (Sirenia: Trichechidae). Oocysts of Eimeria manatus n. sp. are spherical to subsphencal, 11.8 × 10.7 (10.5–13.5 × 9.0–13.5) μ m , with a smooth, thin, bilayered wall; shape index (length/width) 1.1 (1.0–1.3). Micropyle and oocyst residuum absent; polar granule(s) usually present. Sporocysts are ovoid, 8.6 × 5.1 (8.0–9.5 × 5.0–5.5) μm, with thin, membrane–like walls and a knoblike Stieda body; shape index 1.7 (1.4–1.8). Sporozoites elongate, each with a large posterior refractile body. The sporocyst residuum consists of a small cluster or row of few to many small granules. Oocysts of Eimeria nodulosa n. sp. are spherical to subspherical, 15.6 × 14.7 (14.5–17.5 × 13.0–16.0) μm, with a distinctly bilayered wall; shape index 1.1 (1.0–1.2). Unsporulated and freshly sporulated oocysts often possess large, knob–like structures on the external surface of the oocyst wall that support a thin membrane or filament. Micropyle, oocyst residuum and polar granule absent. Sporocysts are ovoid, 10.6 × 5.9 (9.5–12.0 × 5.0–6.5) μm, with a smooth, thin wall and knob–like Stieda body; shape index 1.8 (1.5–2.1). Sporozoites granular and elongate, each with a large posterior refractile body. The sporocyst residuum consists of a loose aggregate or scattered mass of moderately sized granules.     

Isospora thibetana N. Sp. (Apicomplexa, Eimeriidae), a Parasite of the Tibetan Siskin (Serinus thibetanus=Carduelis thibetanus) (Passeriformes, Fringillidae)

Tibetan siskins are birds native to the Himalayan region often imported into Italy for commercial purposes. Fecal examination of 45 imported subjects with clinical signs of diarrhoea revealed the presence of a large number of coccidian oocysls. After sporulation, accomplished by mixing feces with 2.5 % (w/v) acqueous K₂Cr₂O₇ at room temperature (22° C ± 1° C), exogenous stages of an Isospora species were revealed. The oocysts of this Isospora are spherical, have a bilayered colorless wall, and average 23.24 μm × 23.05 μm; oocyst residuum and micropyle are absent, while an oval polar granule is rarely present. The elliptical sporocysts average 18.44 μm × 10.97 μm and the Stieda body protrudes slightly from the end of the sporocyst. A spherical sporocyst residuum is present though it sometimes consists of scattered granules. The spindle-shaped sporozoites average 11.53 μm × 2.86 μm, and have two refractile bodies. The taxonomic position of the tibetan siskin is controversial. Some authors include this species in the genus Serinus , while others include it in the genus Carduelis. The coccidian species isolated from these tibetan siskins was, for this reason. compared with the Isospora species previously described both in the genus Carduelis and in the genus Serinus. As a result of this comparison a new species. Isospora thibetana , was named. In the intestine of dead subjects, oocysts were found only in the ileum where the mucosa was greatly thickened and presented a heavy leucocytic infiltration consisting mainly of lympho-monocytic cells. A similar infiltration was observed in liver and lungs as well.     

Ultrastructure of In Vivo-Produced Caryocysts Containing the Coccidian Caryospora bigenetica (Apicomplexa: Eimerüdae)

A cotton rat was inoculated orally with oocysts of Caryospora bigenetica from the feces of a rattlesnake. Sixteen days later the rat was euthanized, and portions of the scrotum, foot pad and muzzle were processed for histological sections and transmission electron microscopy. Sporozoites within caryocysts had typical coccidian features such as an anterior and posterior refractile body, centrally located nucleus, micronemes, rhoptries, a conoid, a micropore near the anterior refractile body, a posterior pore, amylopectin granules, lipid bodies, a Golgi-like body, a mitochondrion and subpellicular microtubules. The infected host cell was spherical and surrounded by a fibrous wall-like covering, 0.35–1.00 μm thick. This outer covering, when viewed in stained histological sections, was periodic acid-Schiff (PAS)-positive.     

New species of Eimeria Schneider, 1875 and Isospora Schneider, 1881 (Apicomplexa: Eimeriidae) from the short-crested flycatcher Myiarchus ferox (Gmelin) (Passeriformes: Tyrannidae) in South America

In the current study, two new coccidian species (Protozoa: Apicomplexa: Eimeriidae) obtained from short-crested flycatcher Myiarchus ferox (Gmelin) are reported from Brazil. Isospora feroxis n. sp. has o?cysts which are spheroidal to sub-spheroidal, 18.7 × 18.0 μm, with a smooth and bi-layered wall, c. 1.2 μm. The micropyle and o?cyst residuum are absent, but two polar granules are present. Its sporocysts are broadly ellipsoidal and 11.7 × 8.5 μm. Stieda and substieda bodies are present. A sporocyst residuum is present and the sporozoites have a refractile body and nucleus. O?cysts of Eimeria sicki n. sp. are spheroidal to sub-spheroidal, 30.3 × 28.5 μm, with a smooth and bi-layered wall, c. 1.3 μm. The micropyle, o?cyst residuum and polar granule are absent. Its sporocysts are ellipsoidal, 18.4 × 10.0 μm. Stieda and substieda bodies are present. A sporocyst residuum is present and sporozoites have a refractile body and nucleus.     

Transmission Electron Microscopy of Intracellular Sporozoites of Eimeria vermiformis (Apicomplexa,Eucoccidiida) in the Mouse1

ABSTRACT. Sporozoites of Eimeria vermiformis from the mouse were first seen in the epithelial cells of villus tips and the crypts of Lieberkühn four hours after inoculation (HAI). They were always within a parasitophorous vacuole. By 12 HAI, most were in crypt epithelial cells between the basement membrane and host cell nucleus. The sporozoites in the villus tips had 26 subpellicular microtubules, two polar rings, two preconoidal rings, two refractile bodies surrounded by amylopectin-like granules, a lamellar Golgi apparatus, numerous micronemes, and rhoptries. The sporozoites in the crypt cells had fewer amylopectin-like granules, micronemes, and rhoptries. A nucleolus was visible, as were pieces broken off from the posterior refractile body. Later, the sporozoites folded over to become U-shaped; the infolded membranes fused; and then the inner membranes disappeared so that spherical meronts were formed. Folding sporozoites were first seen 16 HAI and persisted until 52 HAI.     

Eimeria carolinensis n. sp., a Coccidium from the White-Footed Mouse, Peromyscus leucopus (Rafinesque)

SYNOPSIS. Eimeria carolinensis n.sp. (Sporozoa) is described from oöcysts in the feces of the white-footed mouse, Peromyscus leucopus (Rafinesque) taken in the vicinity of Durham, North Carolina. The oöcysts are ellipsoidal to elongate ellipsoidal, 14–19.5 × 10–13 μ, mean of 17.6 × 11.3 μ. Micropyle absent. Oöcyst wall composed of 2 layers. A refractile granule present but no oöcyst residuum. Sporocysts ovoid almost filling the oöcyst. Small Stieda body present.     

Transmission electron microscopy of intracellular sporozoites of Eimeria vermiformis (Apicomplexa, Eucoccidiida) in the mouse

Sporozoites of Eimeria vermiformis from the mouse were first seen in the epithelial cells of villus tips and the crypts of Lieberkühn four hours after inoculation (HAI). They were always within a parasitophorous vacuole. By 12 HAI, most were in crypt epithelial cells between the basement membrane and host cell nucleus. The sporozoites in the villus tips had 26 subpellicular microtubules, two polar rings, two preconoidal rings, two refractile bodies surrounded by amylopectin-like granules, a lamellar Golgi apparatus, numerous micronemes, and rhoptries. The sporozoites in the crypt cells had fewer amylopectin-like granules, micronemes, and rhoptries. A nucleolus was visible, as were pieces broken off from the posterior refractile body. Later, the sporozoites folded over to become U-shaped; the infolded membranes fused; and then the inner membranes disappeared so that spherical meronts were formed. Folding sporozoites were first seen 16 HAI and persisted until 52 HAI.     

Coccidia of Brazilian Mammals: Eimeria Marajoensis N. Sp. (Apicomplexa: Eimeriidae) From the Anteater, Tamandua Tetradactyla (Xenarthra: Myrmecophagidae)

ABSTRACT 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 times 13.4 ± 1.4 (11.1-16.5 times 11.1-16.5) μm, shape index (length/width) 1.0 (1.0-1.2). the oocyst wall is a single, Colorless layer about 0.6-1.0 μm 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 μm is consistently present. the sporocysts are broadly ellipsoidal, 7.1 ± 0.7 ± 5.3 ± 0.6 (6.0-8.8 times 4.0-5.7) μm, shape index 1.3 (1.2-1.5), with a delicate wall bearing a 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 times 2.0 μm. Sporocyst refractile bodies were not discernablc.     

Eimeria ornata N. Sp. (Apicomplexa: Eimeriidae) from the Ornate Box Turtle, Terrapene ornata ornata (Reptilia: Testudines), in Texas

Eimeria ornata n. sp. is described from the feces of 6/16 (37.5%) ornate box turtles, Terrapene ornata ornata , in northcentral Texas. Endogenously sporulated oocysts are ellipsoid 17.9 × 15.7(16-21 × 14-18) μm, with a thin, single-layered wall; shape index 1.14 (1.0-1.3). A micropyle is absent but a polar granule was present in one third of the oocysts. An oocyst residuum was present, consisting of numerous small globules situated either in a distinct mass or scattered within the oocyst. The sporocysts are elongate, 11.1 × 5.4 (9-13 × 5-6) μm, with an indistinct Stieda body at 1 pole. A sporocyst residuum is present, consisting either as a compact mass or as scattered granules. The sporozoites are elongate, 9.5 × 2.0 (8-12 × 2) μm, in situ, with spherical anterior and posterior refractile bodies. The new species is distinguished from the similar Eimeria carri Ernst & Forrester, 1973, from eastern box turtles, T. Carolina , by slight differences in oocyst morphology and endogenous sporulation.     

Eimeria turcicus N. Sp. (Apicomplexa: Eimeriidae) from the Mediterranean Gecko, Hemidactylus turcicus (Sauria: Gekkonidae)

ABSTRACT. Eimeria turcicus n. sp. (Apicomplexa: Eimeriidae) is reported from the gall bladder of the Mediterranean gecko, Hemidactylus t. turcicus (Linnaeus, 1758) from the Houston Zoo, Texas, USA. Oocysts of this coccidian are elongate and cylindrical, 38.2 × 17.9 (35.2-40.8 × 16.8-20.0)μm, with a smooth, bilayered wall ∼ 1.6 μm thick; shape index 2.1 (1.9-2.3). A polar granule is present, but a micropyle and oocyst residuum are absent. Sporocysts are ovoid, 11.0 × 8.8 (10.0-12.0 × 8.0-9.4) μm, with a smooth, thin wall and suture; shape index 1.3 (1.1-1.4). Each sporocyst contains a residuum measuring 6.0 × 5.1 (4.8-8.0 × 4.8-6.4) μm, additional residual granules scattered among the sporozoites, and two sporozoites that are normally arranged head-to-tail within the sporocyst. Each sporozoite contains a single, ovoid, posterior refractile body and a central nucleus.