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PubMed1976

Electron microscopy of stages of Isospora felis of the cat in the mesenteric lymph node of the mouse.

Stages of Isospora felis of the cat in the mesenteric lymph node of the mouse 25 days after oral inoculation with oocysts, have been described at the ultrastructural level. The organisms occurred singly within parasitophorous vacuoles in host cell cytoplasm and were sporozoite-like, having a large crystalloid body up to 5.5 mum in length posterior to the nucleus. The size and appearance of the parasitophorous vacuole varied. Some vacuoles contained numerous, small, electron dense granules about 30 nm in diameter. Because of the aggregation of granules and their arrangement within the parasitophorous vacuole, the impression was sometimes gained by light microscopy that parasites were surrounded by a sheath or cyst wall. However, a cyst wall was not present. In host cells, spherical, membrane-bound bodies with a homogeneous, electron dense core and a maximum diameter of 0.25 mum were filed along the limiting membrane of the parasitophorous vacuole. These extra-intestinal parasites were considered to be waiting stages, with a biological function similar to that of the tissue cyst stage of other general of isosporan coccidia.

Animals↗
PubMed1979

Scanning and transmission electron microscopy of the oocyst wall of Isospora lacazei.

The oocyst wall of Isospora lacazei from sparrows was studied with scanning (SEM) and transmission (TEM) electron microscopy. In TEM, the oocyst wall consisted of four distinct layers (L1-4). The innermost layer, L1, was moderately electron-lucent and 240--285 nm thick; L2 was electron-dense and 210--240 nm thick; L3 was moderately electron-lucent and 15--150 nm thick; L4, the outer most layer, was discontinuous and consisted of electron-dense discoid bodies which measured 180--220 nm x 320--840 nm. The discoid bodies of L4 as seen by TEM appeared spheroid in shape when observed by SEM. One or two membranes were situated on or between various layers of the oocyst wall. One such membrane occurred on the inner margin of L1, two closely applied membranes were interposed between L1 and L2, one membrane occurred between L2 and L3, and one membrane on the outer margin of L3.

Animals↗
PubMed1983

Excystation of Isospora suis Biester, 1934 of swine.

The in vitro excystation of sporozoites of Isospora suis Biester 1934 is described. Sporocysts of I. suis lack a Stieda body. Upon incubation in 0.75% sodium taurocholate or in 0.25% trypsin + 0.75% sodium taurocholate excystation solutions, sporozoites were released by separation of the sporocyst wall into four plates. Occasionally, the sporocyst wall did not separate completely but opened partially and released the sporozoite. At the time of excystation, sporozoites were short and broad but became elongated after 5 to 10 min in the excystation fluids. Elongate sporozoites measuring 11.7 x 3.8 micrometers, had a pointed anterior end and a nucleus located in the posterior half of the cell. Living sporozoites exhibited gliding movements, side-to-side flexion, and probed with their anterior ends. Incubation in 5.25% sodium hypochlorite removed the oocyst walls from most oocysts. Sporozoites did not excyst from sporocysts that were released during treatment with sodium hypochlorite.

Animals↗
PubMed2005

Isospora suis: an experimental model for mammalian intestinal coccidiosis.

Piglets experimentally infected with 10,000 oocysts of Isospora suis in three identical trials (n = 50) were examined clinically and coproscopically from 5 to 11 days post-infection (d.p.i.), weighed in weekly intervals until the fourth week of life and compared to age-matched asymptomatic controls (n = 17). Furthermore, 17 infected piglets were histologically examined on days 5-14 p.i. Infected animals had a significantly lower weight gain than the controls and showed diarrhoea throughout, with maximum prevalence and intensity on 6 d.p.i. Half of the animals had diarrhoea for only 2 days or less. The number of diarrhoea days was negatively correlated with weight gain. Oocyst excretion started on 5 d.p.i. with peak prevalences and declined afterwards; a smaller peak was seen on 10 d.p.i. All animals excreted parasites at least once, and most of them excreted for 5-7 days. Oocyst excretion intensity paralleled the prevalence and ranged from 220 to 251,501 oocysts per gram of faeces (opg). Most samples contained 4 x 10(3) to 4 x 10(4) opg. The opg values were negatively correlated with faecal scores (samples with diarrhoea contained less oocysts) of the same day and the previous day. Histologically, necrosis followed by atrophy of the villi was most pronounced in the early stage of infection throughout the jejunum and ileum but declined thereafter. On 14 d.p.i., villous atrophy was still noticeable in the jejunum. Histology is difficult to quantify and requires large animal numbers, although the effects are visible for some time. Weight gain and faecal score can be affected by other factors than parasite infection. From the compiled data, we conclude that the established model is suitable to study piglet isosporosis with oocyst excretion being the most reliable parameter, although individual variations are considerable. A negative correlation between excretion and diarrhoea may be responsible for the difficulties in the detection of the parasite in field samples.

Animals↗
PubMed2006

The relative stability of chronic Isospora sylvianthina (Protozoa: Apicomplexa) infection in blackcaps (Sylvia atricapilla): evaluation of a simplified method of estimating isosporan infection intensity in passerine birds.

Estimation of intensity of coccidia infection in wild birds is essential for the studies of the parasite impact on birds' natural populations. In this paper I propose a method for quantification of coccidia oocyst output from passerine birds applicable in field investigations because it is based on one faeces droplet per bird only. This method was checked under controlled laboratory conditions on blackcaps, chronically infected with Isospora sylvianthina, and was proved to be sensitive enough for the detection of between-individual differences in parasite load. I also show that individual variation in the intensity of isosporan infection in captive blackcaps is relatively stable in time, both in the scale of a few consecutive hours and in that of consecutive days. Hence, the study shows that, in passerine birds, single measurements of oocyst production, when collected in the proper time of day, can be used to characterise some more permanent aspects of an individual's coccidia infection status.

Animals↗
PubMed2000

Life-cycle of Isospora mehlhornii sp. nov. (Apicomplexa : Eimeriidae), parasite of the Egyptian swallow Hirundo rubicola savignii.

Fifty-seven Hirundo rubicola savignii swallows were collected from Damietta, Tanta, Dakahlyia and Sharkia Provinces, Egypt. They were examined for coccidian parasites. The percentage of infection with Isospora stages was 12.3%. After diagnosis it was noted that the parasites belong to a new species. The unsporulated oocysts were spherical, measuring 25.7-31.9 microm in diameter with a mean of 28.3 microm. A micropyle, polar granule and oocyst residuum were absent. Sporocysts appeared lemon-shaped and measured 19.6-24.5 microm x 12.5-17.5 microm with a mean of 22.9 x 14.4 microm. Stieda body and the sporocyst's residual body were clearly visible. Sporozoites measured 11-14.2 x 4.4-5.1 microm with a mean of 11.4 x 4.7 microm. Sporulation time was 72 h at room temperature (25 degrees C). Endogenous stages including schizogony and gamogony were detected in epithelial cells of the duodenum, jejunum and ileum of the host. Schizogony consisted of two generations. Mature first generation schizonts reached up to 11 microm in diameter and produced merozoites measuring 3.5 x 1.7 microm. Mature second generation schizonts measured 17.2 x 12.3 microm and produced merozoites measuring 11.8 x 2.2 microm. Gamogonic stages were differentiated into microgamonts and macrogamonts. Mature microgamonts were spherical and measured 23.2 microm in diameter, producing curved microgametes measuring 4.5 x 0.7 microm. The ovoid macrogametes measured 19.6 x 14.7 microm and were characterized by a large nucleus and nucleolus. Early, more or less spherical, oocysts were detected inside the intestinal epithelial cells and in the intestinal lumen. They measured 19.6 microm in diameter. The sporont measured 17.2 microm in diameter. Cytochemical studies on schizogony, gamogony and oocysts were accomplished and showed distribution of polysaccharides and composition of the oocyst wall.

Animals↗
PubMed2001

Autofluorescence microscopy for the detection of nematode eggs and protozoa, in particular Isospora suis, in swine faeces.

Parasites from swine faeces were examined for autofluorescence. Oocysts of Eimeria polita, E. scabra and Isospora suis, cysts of Balantidium coli and eggs of Oesophagostomum dentatum, Strongyloides ransomi and Trichuris suis (but not those of Ascaris suum) emitted light after excitation with UV light. I. suis oocyst counts in McMaster chambers utilising autofluorescence were compared to those from conventional bright field microscopy. Similarly, faecal smears containing I. suis were examined using the same techniques. Autofluorescence was superior to bright field microscopy in detecting oocysts after flotation and was highly significantly more sensitive when direct smears were examined.

Animals↗
PubMed1984

Life cycle of Isospora suis in gnotobiotic and conventionalized piglets.

Isospora suis had 3 asexual and 1 sexual intra-intestinal conventional life cycle. The first asexual generation was most prominent at 2 days p.i. (post inoculation) and produced 2-7 merozoites. The second-generation meronts were prevalent at 3-4 days p.i. and produced 2-12 large merozoites. At 4-5 days p.i. the third generation meronts were prominent and produced 4-24 small crescent shaped merozoites. Mature sexual stages were most prominent at 5-6 days p.i. The stages were most numerous in the distal half of the small intestine. At 8-9 days p.i. stages morphologically similar to the second generation of meronts reappeared, followed by the further development into third generation merozoites and sexual stages. This was reflected in a prepatent period of 5 days and a biphasic patent period of 5-8 or 9, and 11-14 days p.i. Intraperitoneal injection of liver/spleen and intestinal lymph node homogenates, respectively, from piglets infected 24 and 48 h, previously with high doses of oocysts, resulted in a patent infection 10-12 days post inoculation of the donor piglets. No differences in the life cycle of I. suis were observed between conventionalized and germ-free piglets. An extra-intestinal life cycle of I. suis related to the second patent period was postulated.

Animals↗
PubMed1985

Interfering effect of Isospora suis infection on Salmonella typhimurium infection in swine.

Piglets were each orally inoculated daily for 4 consecutive days, with 10(4)-10(5) nalidixic acid-resistant Salmonella typhimurium and, starting 1 day after inoculation, with 50 000 Isospora suis sporulated oocysts. Control pigs were given S. typhimurium alone following the same inoculation schedule. Fecal samples were taken 5, 7 and 10 days after the coccidial inoculation, and all the pigs were necropsied 13 days after inoculation. S. typhimurium counts in the feces and in the cecal contents and the numbers of pigs positive for presence of S. typhimurium in the mesenteric lymph nodes of the dual-infected pigs were significantly (P less than 0.05) smaller than in those infected with S. typhimurium alone.

Animals↗
PubMed1986

The sporulation time of Isospora suis oocysts from different sources.

Feces containing Isospora suis oocysts were collected from naturally- and experimentally-infected pigs from four different areas of the United States. The unsporulated oocysts were cleaned, concentrated, mixed with 2.5% aqueous potassium dichromate solution, poured into petri dishes to a depth of 5 mm, and incubated at 25 degrees C. The oocysts were examined with a microscope at 12 h intervals and the stages of sporulation present were counted. Although a few oocysts were completely sporulated after 12 h of incubation, in most fecal samples the majority of the oocysts were not completely sporulated until 24 or 36 h. In the present study, the sporulation time of I. suis oocysts was considered to be less than or equal to 48 h. There were no major differences in the sporulation times of I. suis oocysts from the different sources.

Animals↗
PubMed1987

Development of Isospora suis from pigs in primary porcine and bovine cell cultures.

Sporozoites of Isospora suis penetrated and developed by endodyogeny in primary porcine kidney (PPK) and primary fetal bovine kidney (PFBK) cell cultures. Motile merozoites and binucleate Type I meronts were observed in both types of cultured cells. Multinucleate Type II meronts developed in PPK cell cultures only. These multinucleate meronts were always found singly, were nonmotile and did not form merozoites.

Animals↗
PubMed1993

Ultrastructure of Isospora suis during excystation and attempts to demonstrate extraintestinal stages in mice.

Transmission electron microscopy was used to examine the structure of the oocysts, sporocysts and sporozoites of Isospora suis during in vitro excystation. Oocysts were ground in a teflon-coated tissue grinder to free most sporocysts and to allow for exposure of oocysts and sporocysts to excystation medium. The suspension of oocysts and sporocysts was incubated at 37 degrees C for 0-45 min in excystation medium. After incubation, the intact oocysts and sporocysts, excysted sporocysts, and sporozoites in the excystation medium were pelleted by centrifugation and fixed for transmission electron microscopy. The oocyst wall was composed of three layers. Treatment with 1.5% (v/v) sodium hypochlorite solution removed the outer layer. The sporocyst wall was composed of two layers, the inner layer of which was interrupted by sutures. During excystation these sutures separated, allowing release of the sporozoites. Sporozoites were elongate and possessed all of the organelles typical of coccidial sporozoites. Tissues from experimentally inoculated outbred Swiss-Webster or inbred BALB/c mice were examined for extraintestinal stages (monozoic cysts) of I. suis by immunoperoxidase staining using specific antisera. Extraintestinal stages were not observed in mice, including those given methylprednisolone acetate.

Animals↗
PubMed2003

Evaluation of lacto-phenol cotton blue (LPCB) for detection of Cryptosporidium, Cyclospora and Isospora in the wet mount preparation of stool.

Lacto-phenol cotton blue (LPCB) was found to be a useful stain for detection of Cyclospora and Isospora oocysts in direct wet mounts of stool. LPCB stained these parasites blue, and differentiated their internal structures clearly, thereby facilitating detection and accurate identification of these parasites. However, the LPCB staining was not found useful in the identification of Cryptosporidium. The LPCB wet mount is recommended for use in the laboratories where acid-fast staining is not performed routinely, such as in a peripheral laboratory or in a rural health centre in the developing countries.

Animals↗
PubMed1999

Role of acquired immunity and natural age resistance on course of Isospora suis coccidiosis in nursing piglets.

Thirty-two piglets from three litters were experimentally inoculated with 200000 sporulated oocysts of Isospora suis at 3 days of age and/or rechallenged at 19 days of age or primary inoculated at 19 days of age, to compare the role of acquired immunity and natural age resistance on the course of coccidiosis. Twelve piglets were not inoculated and served as a control. Following challenge, the signs of coccidiosis characterised by clinical symptoms, oocysts shedding and weekly weights were similar to those which occurred in piglets primary inoculated at 19 days of age. This comparison suggests that maturation of non-specific components of the immune system plays a more important role in the resistance of neonatal piglets to I. suis infection than specific immune mechanisms.

Aging↗
PubMed1981

Separation of Isospora (Toxoplasma) gondii cysts and cystozoites from mouse brain tissue by continuous density-gradient centrifugation.

A simple, quick and reproducible method consisting of density-gradient centrifugation of homogenized infected mouse brain tissue on Percoll is described for the isolation and purification of cysts of Isospora (Toxoplasma) gondii. A 100% recovery of cysts, with 74.2% in a single fraction with a specific gravity of 1.056, was obtained by overlaying homogenates of infected mouse brains on a pre-formed Percoll gradient and centrifugation at low g forces. With this procedure recovery was independent of the age of the cysts. Titration of purified cystozoites showed there to be no loss of infectivity.

Animals↗
PubMed2000

Isospora lutrae n. sp. (Apicomplexa: Eimeriidae), a new coccidium from the European otter Lutra lutra (L.) (Carnivora: Mustelidae) from Spain.

Parasitological examination of European otter originating from Extremadura, Spain revealed the presence of a new isosporan species. Oöcysts of Isospora lutrae n. sp. are spherical to subspherical, 31.2 (27.5-32) x 29.6 (28-31) microm and have a smooth wall c. 1 microm thick. Sporocysts are ellipsoidal, 18.2 (17-19) x 14.4 (14-16) microm and lack Stieda and substieda bodies. A spherical sporocyst residuum is present, consisting of granules scattered among the sporozoites. Sporozoites are spindle-shaped, 12.4 x 2.5 microm and have anterior and posterior refractile bodies. Based on its unique morphologic structure and host, I. lutrae is considered to be new.

Animals↗
PubMed2002

The role of Isospora suis as a pathogen in conventional piglet production in Germany.

In order to evaluate the prevalence of Isospora suis in conventional piglet production in Germany, pooled faecal samples from 327 pig litters from 18 pig production units (20-320 sows each) were examined. At least 10 litters from each farm were investigated. I. suis was present on 83% of the farms and 42.5% of the litters, the infection rate being highest in the third week of age (48.2%). I. suis was found more frequently in samples of diarrhoea than in firm faeces (49.2% compared to 22.2%). Twenty naturally infected piglets from six of these farms underwent examination post mortem, including histology, virology and bacteriology. Histological examination revealed atrophy of the villi in various degrees, mild crypt hyperplasia, fusion of the villi, metaplastic epithelium, erosions and necrosis, especially in the medium and the posterior jejunum and in the ileum. Asexual and sexual developmental stages of the parasite were found in varying numbers in the epithelium of the whole of the small intestine. Bacteria and viruses were mostly excluded as the cause of diarrhoea, and it was concluded that I. suis was the primary pathogen inducing distinct changes and clinical symptoms of diarrhoea.

Animal Husbandry↗