Life cycles of two isopora species in the canary, Serinus canarius Linnaeus

The endogenous stages of Isospora serini Arog?o and Isospora canaria Box are described from experimentally infected canaries, Serinus canarius Linnaeus. Unlike other Coccidia, the first part of the I. serini life cycle takes place in mononuclear phagocytes. Five asexual generations are described from this cell type; 2 additional asexual generations and the sexual stages take place in the intestinal epithelium. Isospora canaria, on the other hand, has a conventional coccidian life cycle in that all of the endogenous stages are in the epithelium of the small intestine, with 3 asexual generations and the sexual generation described in the duodenal epithelium. The 2 species differ in their position relative to the nucleus of the intestinal epithelial cell. Isospora serini is usually on the lumenal side of the nucleus while I. canaria is below the nucleus, toward the basement membrane. The prepatent period is 4-5 days for I. canaria and 9-10 days for I. serini. Patency lasts for 11-13 days in I. canaria infections, but duration of oocyst output is more chronic in I. serini infections, persisting for as long as 231 days. Both species have a diurnal periodicity of oocyst discharge which occurs in late afternoon and evening.     

Exogenous Stages of Isospora serini (Aragão) and Isospora canaria sp. n. in the canary (serinus canarius Linnaeus)*

Exogenous stages of Isospora serini (Aragão) and Isospora canaria sp. n. from the canary (Serinus canarius Linnaeus) are described. Oocysts of I. serini are spheroid and average 19.2 × 20.1 μ m, while those of I. canaria are larger, more ellipsoid, and average 21.8 × 24.6 μ m. No oocyst residuum is present and the oocyst walls of both species are colorless, transparent, and single layered. Sporocysts average 9.4 × 15.2 μ m for I. serini and 11.5 × 18.1 μ m for I. canaria. The I. canaria sporocyst has a substiedal body, but none was found in I. serini sporocysts. Both species have a spherical sporocyst residuum; this was obscured in the I. serini sporocyst by scattered granules. Living sporozoites of I. canaria average 3.6 × 16.9 μ m and have 1 to 3 refractile globules; those of I. serini have 2 globules and average 2.8 × 12.6 μ m. A disseminated infection of the mononuclear phagocytes results from administration of I. serini while I. canaria oocysts give rise to a typical coccidian infection restricted to the intestinal epithelium. Asexual stages of I. serini in macrophages are indistinguishable from parasites previously called avian Toxoplasma, Atoxoplasma, and Lankesterella.     

Life Cycle of Isospora canis Nemeséri, 1959 in the Dog*

The life cycle of I. canis Nemeséri, 1959 was studied in experimentally infected dogs. Freshly sporulated oocysts were ovoid and 34–40 × 28–32 μm. The endogenous stages were found directly beneath the epithelium of the distal portion of the small intestinal villi. Most of the endogenous stages were in the lower 1/3 of the small intestine, but occasionally they were found in other portions of the small intestine. Three asexual generations were present. First-generation schizonts were 16–38 × 11–23 μm and contained 4–24 merozoites; mature 1st-generation merozoites were 8–11 × 3–5 μm. First-generation schizogony lasted up to 7 days after inoculation. Second-generation schizonts were 12–18 × 8–13 μm and contained up to 12 merozoites which were 11–13 × 3–5 μm. Second-generation schizogony was present on postinoculation days 6 and 7. Third-generation schizonts were formed by nuclear division of 2nd-generation merozoites. Most 2nd-generation merozoites underwent nuclear division without leaving the parasitophorous vacuole of the 2nd-generation schizont. Mature 3rd-generation schizonts were 13–38 × 8–24 μm and contained 6–72 merozoites. Third-generation merozoites were 8–13 × 1–3 μm. Third-generation schizogony was present on days 6–8 after inoculation. Mature macrogametes were 22–29 × 14–23 μm. Mature microgametocytes were 20–38 × 14–26 μm. Gametes were present on postinoculation days 7–10. Oocysts were present in tissue sections on postinoculation days 8–10 and 12. The prepatent period was 9–11 days.     

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.     

Coccidiosis as a cause of transmural lymphocytic enteritis and mortality in captive Nashville warblers (Vermivora ruficapilla).

Transmural lymphocytic enteritis was diagnosed in thirteen Nashville warblers (Vermivora ruficapilla) during an epornitic with high mortality. In the intestinal lesions, asexual stages of coccidia were present within lymphocytes and asexual and sexual stages of coccidia were present within intestinal villar epithelium. Ultrastructurally, the infiltrating lymphocytes resembled granular ("intraepithelial") lymphocytes, a cell known to be important in the life cycle of some avian coccidia. Gross and histopathologic features of this enteritis resemble intestinal changes described for Isospora/Atoxoplasma spp. in other passeriformes and lymphoproliferative disease in gold-finches.     

Experimental Isospora canis and Isospora felis Infection in Mice,Cats, and Dogs*

SYNOPSIS. Two 6-month-old gnotobiotic dogs and 4 five-day-old dogs became infected but did not shed oocysts within 15 days after ingesting the feline coccidian, Isospora felis. Infection of the dogs was evidenced by the shedding of I. felis oocysts by cats consuming extra-intestinal organs of dogs fed I. felis. Likewise, cats became infected with the canine coccidian, Isospora canis, without producing oocysts. Dogs also became infected after ingesting mice previously fed I. canis oocysts. The prcpatent period for I. canis was slightly shorter in dogs fed infected mice (8–9 days) than in those fed oocysts (9–11 days).     

Isospora as an Extraintestinal Parasite of Passerine Birds1

Toxoplasma-like avian parasites inhabiting mononuclear phagocytes have been called Haemogregarina, Toxoplasma. avian Toxoplasma, Atoxoplasma, and Lankesterella by various authors. My attempts to transmit the parasites by bloodsucking mites or by transfer of blood and tissues of infected sparrows and canaries were unsuccessful. However, it was noted that the infection was exacerbated under conditions that favored transmission of coccidiosis: crowding and lack of cleanliness. Oral inoculation of sporulated oocysts of Isospora resulted in death from overwhelming macrophage infection with Toxoplasma-like organisms. Experiments using sparrows and canaries showed that the Isospora species involved was not cross infectious. Further investigations using canaries demonstrated that after oral oocyst inoculation, infection of macrophages spread from the submucosa of the duodenum to the liver. spleen, and lungs. After several generations in the internal organs, asexual multiplication, occured in the intestinal epithelium of the small intestinc. Fecal oocysts first appeared at the end of 9–10 days. Oocysts continued to be passed in the feces for months after infection. This chronicity may be explained by the relatively long life of the macrophages that serve as host cells for the asexual stages as compared to the intestinal epithelium which is the cell type parasitized by conventional coccidia.     

Endogenous Stages of the Life Cycle of Isospora rivolta in the Dog

SYNOPSIS. Coccidia-free beagle puppies were experimentally infected with a cloned culture of Isospora rivolta oocysts. The endogenous stages were found in the posterior 1/2 of the small intestine, and rarely in the cecum and colon. Maximum numbers of all stages occurred just anterior to the ileocecal valve. Endogenous stages were found in the distal third of the villi, predominantly parasitizing subepithelial cells of the lamina propria; however, stages were occasionally present in epithelial cells. The number of asexual generations could not be determined from their structure, but evidence based on oocyst production suggested that there were at least 2 asexual generations. The schizonts were 17–24 by 12–25 μ and contained 4–24 merozoites, the most common number being 4 or 8. Schizonts with mature merozoites were found as early as 72 hr, but were present in maximum numbers at 96 hr. Merozoites had slender curved bodies and were 10.5–13.4 by 2.3–3.0 μ. Mature gamonts were found by 144 hr. Mature microgametocytes were 13.4 by 8.7 μ and contained 50–70 microgametes. Microgametes had slightly curved tapering bodies (5.8–6.4 by 0.6 μ) with 2 posteriorly directed flagella 11–14 μ long. Mature macrogametes had reticular cytoplasm and a uniformly large nucleus and nucleolus.
The prepatent period was 142–146 hr. The patent period was 13–23 days with an average of 19 days.     

Eimeria cicaki sp. n. and Isospora thavari sp. n. from the House Lizard Gehyra mutilata Boulenger in Malaysia*

SYNOPSIS. Oocysts and endogenous stages of new species of Eimeria and Isospora from the house lizard, Gehyra mutilata, are described. The ellipsoid to subspherical 2-layered oocysts of E. cicaki averaged 24.0 × 21.0 μm. Polar granules are present. Micropyle and oocyst residuum are absent. Ellipsoid sporocysts average 12.2 × 9.0 μm. A sporocyst residuum is present, but the Stieda body is absent. Endogenous stages are in epithelial cells of the small intestine. The subspherical single-layered oocysts of I. thavari average 23.8 × 22.8 μm. The polar granule is present; micropyle and oocyst residuum are absent. Ellipsoid sporocysts average 12.8 × 9.4 μm. Stieda body and sporocyst residuum are present. There are endogenous stages in epithelial cells of the small intestine.     

Fine Structure of the Oocyst Walls of Isospora serini and Isospora canaria and Excystation of Isospora serini From the Canary, Serinus canarius L.

SYNOPSIS. Oocysts of Isospora serini and Isospora canaria , from the canary Serinus canarius , were broken, added to a cell suspension, fixed in Karnovsky's fluid, and studied in the electron microscope. The oocyst wall of each species had an electronlucent inner layer, a more osmiophilic middle layer and an outer layer of electron-lucent ( I. serini ) or electron-dense material interspersed with some electron-lucent material ( I. canaria ). A few, relatively large lipid-like bodies were present in the outer or middle layer of the oocyst wall of I. canaria. As many as 9 membranes were present in the oocyst wall of I. canaria and 3 in that of I. serini. When exposed to a trypsin-sodium taurocholate fluid, sporozoites of I. serini excysted from 5-month-old sporocysts in vitro , but not from sporocysts stored for more than 6 months. No excystation occurred in 15-month-old I. canaria sporocysts. Similarities and differences in excystation between I. serini and other Isospora, Eimeria , and Sarcocystis species are discussed.     

The fine structure of the endogenous stages of Isospora hemidactyli Carini, 1936 in the Gecko Hemidactylus mabouia from North Brazil

The ultrastructure is described of the meronts, microgamonts and young oocyst stages of Isospora hemidactyli of the gecko Hemidactylus mabouia from Belém, PA, north Brazil. The endogenous stages all develop in the nucleus of the gut epithelial cells. The nucleus remains intact up to the latest stages of the parasite's development, but degenerates by the time the oocyst appears. Merogonic division appears to be asynchronous, and some of the differentiated merozoites contained more than one nucleus. Microgamonts conform in structure with those of other eimeriids. Some of the type 2 wall-forming bodies disintegrate into smaller globules and ground substance of lower density.     

Coccidian-like Nature of Toxoplasma gondii

Specific pathogen-free domestic cats were fed with tissue cysts containing Toxoplasma gondii. In two infected cats large numbers of oocysts were produced in the faeces; no oocysts were observed in the faeces of the uninfected control cat. Five days after the feeding of the toxoplasms profuse schizogonic and gametogonic stages were observed in the epithelial cells of the small intestine of one infected cat. A single schizont was observed in an intestinal epithelial cell of a second cat six days after being fed the tissue cysts. There was no evidence of schizogony or gametogony in the uninfected control cat. The stages observed in the intestinal epithelium are identical with those of the well-known endogenous cycles of coccidian parasites. The appearance of these stages, together with the nature of the oocyst, indicates that T. gondii is a coccidian parasite closely related to the genus Isospora.     

Exogenous stages of Isospora serini (Arag?o)and Isospora canaria sp. n. in the canary (Serinus canarius Linnaeus).

Exogenous stages of Isospora serini (Aragao) and Isospora canaria sp. n. from the canary (Serinus canarius Linnaeus) are described. Oocytes of I. serini are spheroid and average 19.2 times 20.1 mum, while those of I. canaria are larger, more ellipsoid, and average 21.8 times 24.6 mum. No oocyst residuum is present and the oocyst walls of both species are colorless, transparent, and single layered. Sporocysts average 9.4 times 15.2 mum for I. serini and 11.5 times 18.1 mum for I. canaria. The I. canaria sporocyst has a substiedal body, but none was found in I. serini sporocysts. Both species have a spherical sporocyst residuum; this was obscured in the I. serini sporocyst by scattered granules. Living sporozoites of I. canaria average 3.6 times 16.9 mum and have 1 to 3 refractile globules; those of I. serini have 2 globules and average 2.8 times 12.6 mum. A disseminated infection of the mononuclear phagocytes results from administration of I. serini while I. canaria oocysts give rise to a typical coccidian infection restricted to the intestinal epithelium. Asexual stages of I. serini in macrophages are indistinguishable from parasites previously called avian Toxoplasma, Atoxoplasma, and Lankesterella.     

Isospora vulpina Nieschulz and Bos, 1933: Description,and Transmission from the Fox (Vulpes vulpes) to the Dog*†

SYNOPSIS. Oocysts of Isospora vulpina were found in silver foxes (Vulpes vulpes) on a fox farm in Wisconsin. They were 29.7 (25-38) × 24.3 (21-32) μm. The sporocysts were 17.7 (15–23) × 13 (11–16) μm. Five coccidia-free puppies were inoculated with 22,000–42,000 oocysts each of I. vulpina from the fox: a patent infection resulted after 6-7 days. The infection was then transferred from 1 of these dogs to another coccidia-free puppy. After a 7-day prepatent period the puppy passed oocysts for 7 days.     

The Life Cycle of Isospora felis Wenyon, 1923, a Coccidium of the Cat*

SYNOPSIS. A pure strain of Isospora felis derived from a single oocyst was used to study the endogenous cycle. One and a half to two-month-old laboratory-reared, coccidia-free kittens were used thruout the study. The endogenous stages occurred in the epithelial cells of the distal parts of the villi in the ileum and occasionally duodenum and jejunum. All stages lay above the host cell nucleus. There were 3 asexual generations. The 1st generation schizonts were 11–30 by 10–23 μ when mature and contained 16–17 banana-shaped merozoites 11–15 by 3–5 μ. They became mature in 96 or sometimes in 120 hours. The 1st generation merozoites entered new host cells, rounded up and formed 2nd generation schizonts. These formed within themselves 2–10 or more spindle-shaped bodies resembling 1st generation merozoites in shape and size. These were 2nd generation merozoites. They were uninucleate 120 hours after inoculation, but by 144 hours they became larger, multinucleate and some lost their elongate shape and became ovoid. They were then 3rd generation schizonts. They were 12–16 by 4–5 μ. Each formed up to 6 or more banana-shaped merozoites 6–8 by 1–2 μ. The 3rd generation schizonts and merozoites developed within the same host cell and parasitophorous vacuole as the 2nd generation schizonts and merozoites. Mature schizonts containing only 3rd generation merozoites appeared 144 hours after inoculation, were most abundant 168 hours after inoculation, and might be present as late as 216 hours after inoculation. They were 14–36 by 13–22 μ and contained 36 to more than 70 merozoites. The 3rd generation merozoites entered the sexual cycle. The mature microgametocytes were 24–72 by 18–32 μ and contained a central residuum and a large number of microgametes 5–7 by 0.8 μ with 2 posteriorly-directed flagella. The mature macrogametes were 16–22 by 8–13 μ. Gametogony occurred 144–216 hours after inoculation. The prepatent period was 168–192 hours and the patent period 10–11 days. Peak oocyst production occurred on the 6th day of the patent period.     

The Life Cycle of Cryptosporidium baileyi n. sp. (Apicomplexa, Cryptosporidiidae) Infecting Chickens

ABSTRACT. The life cycle and morphology of a previously undescribed species of Cryptosporidium isolated from commercial broiler chickens is described. The prepatent period for Cryptosporidium baileyi n. sp. was three days post oral inoculation (PI) of oocysts, and the patent period was days 4–24 PI for chickens inoculated at two days of age and days 4–14 for chickens inoculated at one and six months of age. During the first three days PI, most developmental stages of C. baileyi were found in the microvillous region of enterocytes of the ileum and large intestine. By day 4 PI, most parasites occurred in enterocytes of the cloaca and bursa of Fabricius (BF). Mature Type I meronts with eight merozoites first appeared 12 h PI and measured 5.0 × 4.9 μm. Mature Type II meronts with four merozoites and a large granular residuum first appeared 48 h PI and measured 5.1 × 5.1 μm. Type I meronts with eight short merozoites and a large homogeneous residuum first appeared 72 h PI and measured 5.2 × 5.1 μm. Microgamonts (4.0 × 4.0 μm) produced 16 micro-gametes that penetrated into macrogametes (4.7 × 4.7 μm). Macrogametes gave rise to two types of oocysts that sporulated within the host cells. Most were thick-walled oocysts (6.3 × 5.2 μm), the resistant forms that passed unaltered in the feces. Some were thin-walled oocysts whose wall (membrane) readily ruptured upon release from the host cell. Sporozoites from thin-walled oocysts were observed penetrating enterocytes in mucosal smears. The presence of thin-walled, autoinfective oocysts and the recycling of Type I meronts may explain why chickens develop heavy intestinal infections lasting up to 21 days. Oocysts of C. baileyi were inoculated orally into several animals to determine its host specificity. Cryptosporidium baileyi did not produce infections in suckling mice and goats or in two-dayold or two-week-old quail. One of six 10-day-old turkeys had small numbers of asexual stages only in the BF. Four of six one-day-old turkeys developed mild infections only in the BF, and sexual stages of the parasite were observed in only one of the four. All seven one-day-old ducks and seven two-day-old geese developed heavy infections only in the BF with all known developmental stages present.     

Morphological and molecular characterization of Isospora amphiboluri (Apicomplexa: Eimeriidae), a coccidian parasite,in a central netted dragon (Ctenophorus nuchalis) (De Vis, 1884) in Australia

An Isospora species, Isospora amphiboluri, originally described by Canon in 1967 and later by McAllister et al. (1995), was isolated from a central netted dragon (Ctenophorus nuchalis) housed at a wildlife rehabilitation centre in Perth, Western Australia. Sporulated oocysts of Isospora amphiboluri (n = 30) are spherical, 24.2 (26.5–23.0) μm in length and 23.9 (22.4–25.9) μm in width, with a shape index of 1.01. The bilayered oocyst wall is smooth and light-yellow in color. Polar granule, oocyst residuum and micropyle are absent. The sporocysts are lemon-shaped, 15.7 (15.2–18.0) × 10.2 (8.9–11.2) μm, with a shape index (length/width) of 1.53. Stieda and substieda bodies are present, the Stieda body being small and hemidome-shaped and the substieda half-moon-shaped. Each sporocyst contains four vermiform sporozoites arranged head to tail. The sporozoites are 11.7 (9.9–16.2) × 3.0 (2.4–3.5) μm, with a shape index (length/width) of 3.87. A sporocyst residuum is present. Sporozoites contain a central nucleus with a finely distributed granular residuum. Comparison of oocyst measurements and their features with other valid Isospora species from hosts in the Agamid family confirmed that this Isospora species is Isospora amphiboluri. Molecular characterization of I. amphiboluri at the 18S rRNA and MTCOI loci showed the highest similarity with I. amphiboluri from the central bearded dragon, 99.8% and 99.7% respectively. This is the first report of I. amphiboluri from a central netted dragon in Australia.     

Eimeria cicaki sp. n. and Isospora thavari sp. n. from the house lizard Gehyra mutilata Boulenger in Malaysia.

Oocysts and endogenous stages of new species of Eimeria and Isospora from the house lizard, Gehyra mutilata, are described. The ellipsoid to subspherical 2-layered oocysts of E. cicaki averaged 24.0 X 21.0 mum. Polar granules are present. Micropyle and oocyst residuum are absent. Ellipsoid sporocysts average 12.2 X 9.0 mum. A sporocyst residuum is present, but the Stieda body is absent. Endogenous stages are in epithelial cells of the small intestine. The subspherical single-layered oocysts of I. thavari average 23.8 X 22.8 mum. The polar granule is present; micropyle and oocyst residuum are absent. Ellipsoid sporocysts average 12.8 X 9.4 mum. Stieda body and sporocyst residuum are present. There are endogenous stages in epithelial cells of the small intestine.     

Cytochemical localization of acid mucosubstances within intestinal tissue stages of Eimeria acervulina and E. necatrix

Synopsis The distribution of acid mucopolysaccharides in the intestinal tissue stages ofEimeria acervulina andE. necatrix has been investigated. The results show that acid mucopolysaccharides are present in the asexual stages of both species and in the sexual stages ofE. acervulina. It is suggested that an esterified hyaluronic acid-like molecule is present in the cytoplasm of schizonts, merozoites, microgametocytes, macrogametocytes and oocysts as well as in the plastic granules of macrogametocytes and the oocyst wall. Sulphated mucopolysaccharides of the chondroitin type occur as additional components in the cytoplasm of the above stages, as well as in large amounts in the perinuclear area of macrogametocytes and oocysts. The functional significance of acid mucopolysaccharides in the coccidial stages is discussed.     

Isospora dawadimiensis n. sp. (Protozoa: Eimeriidae) from the Jerboa (Jaculus jaculus) in Saudi Arabia

Isospora dawadimiensis n. sp. is described from the jerboa, Jaculus jaculus, from Dawadimi, Saudi Arabia. Sporulated oocysts of I. dawadimiensis n. sp. were ovoidal or nearly subspherical 22–26.5 times 20.5–22 μm (24.4 times 21.4 μm). Oocyst wall had one layer. Micropyle, oocyst residuum, and polar granule were absent. Sporocysts were ellipsoid 12–16.5 times 9–10.5 μm (14.6 times 9.9 μm). Sporocyst residuum was present. The sporocysts lack a Stieda body. Sporozoites 8–11 times 2–3 μm (10 times 2.6 μm) were sausage-shaped, slightly curved, and tapered at one end.