The pathogenicity of rabbit coccidium Eimeria coecicola Cheissin, 1947

The pathogenicity of Eimeria coecicola for rabbits has been demonstrated in our experiments. The animals suffered from prolonged affection of appendix lasting at least 20 days. Pathological changes appeared with the development of merogony since day 4 post infection (DPI) and were characterized by an inflammatory infiltration and abundant pyogenic component in lamina propria, swelling and coalescence of upper parts of appendix mucosa above atrophied domes, where spaces filled with stagnating inflammatory exudate, endogenic stages of coccidia, and desquamated epithelia are formed. The alteration of the epithelium and exposure of the appendix lamina propria occur in relation with the gametogony in the period of about 10 DPI. Since 8 DPI, the epithelium of the infected endogenic stages of coccidia becomes hyperplastic, proliferates into lamina propria and is subjected to necrosis. Groups of immature oocysts and their fragments remain in lamina propria and are resorbed, at least for 10 days, by granulomatous inflammatory structures with abundant multinucleate cells of the type of foreign body cells.     

Life cycle of Eimeria coecicola Cheissin, 1947

Life cycle of Eimeria coecicola was studied in experimentally infected rabbits by light microscopy and by transmission and scanning electron microscopy. First and second generation meronts developed in the vermiform appendix; third and fourth generation meronts were located in the epithelium of the ileum. Gametogony developed again in the vermiform appendix. The prepatent period was 9 days. New data were obtained by the study of asexual reproduction. First generation meronts were first observed 4 days post infection (DPI), which is relatively late in comparison with other species of rabbit coccidia. Sporozoites were found in lymphatic follicles of the vermiform appendix at 4 DPI by transmission electron microscopy. This suggests, together with selective location of first generation meronts in the epithelium adjacent to these follicles, that major part of sporozoites enter the epithelium cells through lymphatic follicles and not through the lumen of the vermiform appendix. The process of development of first generation merozoites is similar to endodyogeny. The differences are in formation of apical parts of daughter merozoites which is not coincidental with nuclear division and in formation of the outer membrane of pellicle which arises within the mother cell. Some first generation merozoites have 2-3 nuclei, second and fourth generation merozoites are only uninucleate, while third generation merozoites are only multinucleate. We found that further merozoites are formed in multinucleate third generation merozoites by endopolygeny.     

Efficacy of salinomycin, monensin and lasalocid against spontaneous eimeria infection in rabbits

Rabbits spontaneously infected with coccidia of the genus Eimeria were treated with salinomycin, lasalocid and monensin. The drugs were applied in pellets in the doses of 50 ppm. The weight gain in rabbits treated with salinomycin and monensin was higher than in those treated with lasalocid and by 22.6% higher than in control animals. The weight gain in animals treated with lasalocid was almost the same as in the control group. The oocyst production was suppressed most significantly by salinomycin.     

Description of Eimeria vejdovskyi sp.n. and redescription of Eimeria media Kessel, 1929 from the rabbit

On the basis of oocyst morphology, endogenous cycles, prepatent period, and enzyme analysis, Eimeria media was found to be a composite species, representing two independent species differing from all other species of rabbit coccidia. One of them was designated Eimeria media Kessel, 1929 and the other was described as a new species, Eimeria vejdovskyi. E. media has relatively larger oocysts (mean size 32.88 X 19.19 micron), the endogenous development takes place in the epithelium of the ileum or of posterior jejunum, and the developmental stages gradually migrate from the crypts towards the tips of villi. E. media forms three asexual generations, the prepatent period is 9 days. Eimeria vejdovskyi sp.n. has relatively smaller oocysts (29.05 X 18.18 micron) and is localized throughout the small intestine. E. vejdovskyi sp.n. forms two asexual generations, which are localized mostly in the upper part of villi, like the gametogony. At the beginning of the endogenous development the parasites were localized mostly in the epithelium, while the second asexual generation and gametogony took place also in the lamina propria. The prepatent period was 6 days. It was found that the two species differ from one another in the electrophoretic mobility of lactate dehydrogenase and glucosophosphate isomerase.     

The life cycle of Eimeria danailovi from ducks.

The life cycle of Eimeria danailovi Gr?fner, Graubmann et Betke in experimentally infected ducks was studied by optical microscopy. The asexual generation developed in the posterior part of jejunum and in the whole ileum. The sexual stages occurred in jejunum and ileum, and, in addition, in cecum and colon. All endogenous stages were localized in the cytoplasm of epithelial cells in the apical and basal parts of villi. Two generations of meronts were found to develop, differing from one another in the number of merozoites. The meronts of the first generation were observed 2 days post infection (DPI) and contained 10-14 (on the average 11) merozoites. The second generation of meronts, containing 12-22 (on the average 16) merozoites, developed on 3 DPI. The sexual stages were found in histological preparations on 5 and 6 DPI. They appeared in the faces of experimentally infected ducks first on 5 DPI and they were shed for three days. Oocyst sporulation at room temperature lasted 2-3 days.     

Some remarks on the prevalence and species composition of hare coccidia

In the period between autumn 1983 and winter 1985, 33 digestive tracts and 317 coprological samples of hares were examined. The prevalence of individual coccidian species was reported on the basis of the examination of both the digestive tracts and coprological samples. The following coccidian species were found: Eimeria babatica (with 26.4% prevalence in the season 1983/1984 and 31.1% in 1984/1985), E. europaea (21.2% and 30.3%), E. hungarica (6.5% and 7.6%), E. leporis (24.2% and 45.4%), E. macrosculpta (1.3% and 2.5%), E. robertsoni (36.8% and 29.4%), E. sculpta (6.9% and 13.4%), E. semisculpta (15.6% and 10.0%), and E. townsendi (67.1% and 74.8%), respectively. The species E. babatica, E. macrosculpta, and E. sculpta were recorded in Czechoslovakia for the first time. The oocyst morphology and location of coccidia in the digestive tracts of hares were studied.     

Pathogenicity and ultrastructural pathology of Eimeria debliecki (Douwes, 1921) in experimentally infected pigs

It was confirmed, after experimental infection of 24 weaned pigs with different doses (200,000 and 4 mil.) of Eimeria debliecki oocysts that the developmental cycle of E. debliecki occurs in the anterior jejunum and after a high dose of oocysts also in the duodenum and anterior parts of the middle jejunum. Pathological changes characterized by a light atrophy of the villi, scarcely dispersed minute erosions of the epithelium in upper parts of the mucosa and an inflammatory response in the propria of the anterior jejunum were found in the area of the largest occurrence of developmental stages of E. debliecki (from 50 cm to 100 cm from the pylorus). An inflammatory infiltrate in the propria of the anterior jejunum from 3 DPI to 5 DPI contained a conspicuously large number of plasma cells with Russell bodies. Cellular changes were detected only in enterocytes with developmental stages of E. debliecki. Changes of the microvillous zone were observed in infected enterocytes; dilated mitochondria, free ribosomes and an increased number of residual bodies were found in the cytoplasm of enterocytes. The degree of the cellular changes of enterocytes was dependent on the maturity of the developmental stage of E. debliecki. Based on pathological changes observed by the use of light and electron microscopy, the coccidium E. debliecki is considered to be pathogenic for weaned pigs in spite it does not provoke a clinical infection.     

Enzyme variants of Eimeria parasitizing the domestic fowl and possibilities of species diagnostics.

Electrophoretic variation of the enzymes lactate dehydrogenase (LDH) and glucosephosphate isomerase (GPI) of Eimeria parasitizing the domestic fowl in Czechoslovakia is summarized and the differentiation of species of poultry coccidia is discussed. A new method for evaluation of zymograms of coccidial enzymes is presented. This method enables the results of different experiments to be compared by calculating standardized rates of mobility of each enzyme band relative to the positions of reference variants coded LDH-8 or GPI-9.     

Dynamics of antibody production in mice infected with Toxascaris leonina Linstow, 1909

Using counterimmunoelectrophoresis and ELISA tests the dynamics of antibody production in serum of mice experimentally infected with Toxascaris leonina was studied. The production of antibodies using both tests has already been detectable in serum of mice from 7 days post infection (DPI) and their level persisted till the end of the experiment, i.e. till 77 DPI. The most positive were reactions of sera with Antigens 1 and 3.     

Effect of Host Plant Resistance to Tomato yellow leaf curl virus (TYLCV) on Virus Acquisition and Transmission by Its Whitefly Vector

ABSTRACT The effect that Tomato yellow leaf curl virus (TYLCV)-infected resistant tomato plants may have on virus epidemiology was studied. Four tomato genotypes that exhibit different levels of viral resistance, ranging from fully susceptible to highly resistant, served as TYLCV-infected source plants. Viral acquisition and transmission rates by white-flies following feeding on the different source plants were evaluated. TYLCV transmission rate by whiteflies that had fed on infected source plants 21 days postinoculation (DPI), shortly after the appearance of TYLCV symptoms, was negatively correlated with the level of resistance displayed by the source plant. Therefore, the higher the resistance, the lower the transmission rate. In addition, TYLCV DNA accumulation was shown to be lower in the resistant source plants compared with the susceptible plants. Whitefly survival rate, following feeding on source plants 21 DPI, was similar for all the cultivars tested. Significant differences in whitefly survival were found, however, following feeding on the infected source plants at 35 DPI; here, whitefly survival rate increased with higher levels of resistance displayed by the source plant. At 35 DPI, the susceptible plants had developed severe TYLCV disease symptoms, and transmission rates from these plants were the lowest, presumably due to the poor condition of these plants. Transmission rates from source plants displaying a medium level of resistance level were highest, with rates declining following feeding on source plants displaying higher levels of TYLCV resistance. TYLCV DNA accumulation in whiteflies following feeding on infected source plants at both 21 and 35 DPI was directly correlated with viral DNA accumulation in source plants. Results show that, in essence, the higher the resistance expressed, the less suitable the plant was as a viral source. Consequently, following acquisition from a highly resistant plant, TYLCV transmission by whiteflies will be less efficient.     

A description of two new species of coccidia (Apicomplexa: Eimeriidae) from African reptiles with nomenclatural corrections for two Caryospora and one Eimeria species from snakes

Two new species of coccidian parasites are described from African reptiles. Oocysts of Eimeria foulshami sp. n. from the plated lizard Gerrhosaurus major bottegoi Del Prato of Sudan are ellipsoidal, 24.1 x 14.9 (23-26.5 x 14-17.8) microm with a bilayered, colourless oocyst wall and lack polar granules. The ellipsoidal sporocysts average 8.6 x 4.6 (7-10.6 x 4.4-7) microm and possess a prominent, globular, sporocyst residuum. Oocysts of Caryospora regentensis sp. n. from the Eastern green mamba Dendroaspis augusticeps Smith, 1849 [corrected] of Kenya are spherical to subspherical, 16.8 x 16.4 (16-17.6 x 15-17.2) microm with a bilayered oocyst wall and a single polar granule. The ellipsoidal sporocysts average 13.0 x 10.3 (10.2-14 x 9.2-11) microm and possess a Stieda and substieda body and a prominent globular sporocyst residuum. Oocysts of Caryospora legeri Hoare, 1933 are reported from a hissing sand snake, Psammophis sibilans sibilans L. from Nigeria, representing a new geographical record. The oocysts are slightly larger than the type, but otherwise identical. Caryospora psammophi Bray, 1960 and C. hermae Bray, 1960 from Psammophis sibilans phillipsi, oocysts of which are morphologically similar to and overlap in dimensions with C. legeri Hoare, 1933, are synonymised with the latter species. Eimeria samiae Iskander et Tadros, 1979 is emended to E. samyadeli to reflect the gender of the person the species was named after and because E. sani is preoccupied. In addition to these findings, Eimeria bohemi Modry, Slapeta et Koudela, 2000 and oocysts of an unidentified spherical Eimieria sp. are reported from Chamaeleo dilepis dilepis Leach from Cameroon.     

Genetic characterisation of Giardia duodenalis in dairy cattle in Brazil

The intestinal protozoan parasite Giardia duodenalis (Lambl, 1859) Kofoid & Christiansen, 1915 [syn. Giardia intestinalis and Giardia lamblia] has emerged as a widespread enteric pathogen in humans and domestic animals. In recent years, G. duodenalis has been found in cattle worldwide and longitudinal studies have reported cumulative prevalence of 100% in some herds. In the present study, we determined the prevalence and genetic characterisation of G. duodenalis in 200 dairy cattle from 10 dairy farms in S?o Paulo state, Brazil. All faecal specimens were screened for the presence of G. duodenalis using microscopy examination, enzyme immunoassay (EIA) and polymerase chain reaction (PCR). DNA was extracted from faecal samples and G. duodenalis were identified by amplification of the small subunit ribosomal (SSU-rDNA) and glutamate dehydrogenase (GDH) genes followed by restriction fragment length polymorphism (RFLP) or sequencing analysis. Giardia was identified in eight farm locations (80% prevalence). Overall, 15/200 (7.5%) animals were positive for infection, only one of which was a cow. Giardia duodenalis genotype E was present in 14 of the animals tested. Zoonotic genotype AI was present in one positive sample. Genotype E and genotype A represented 93% and 7% of G. duodenalis infections, respectively. This study demonstrates that G. duodenalis infection was prevalent in dairy calves in S?o Paulo state and that the non-zoonotic genotype E predominates in cattle in this region. Nevertheless, calves naturally infected in Brazil can shed Giardia cysts that can potentially infect humans, and thus, they may represent a public health risk.     

Intestinal parasites: a study of human appendices

Histological sections of 414 appendices were examined parasitologically. Enterobius vermicularis was found in 8.7%, eggs of Ascaris lumbricoides in 0.5%, trophozites of Dientamoeba fragilis in 4.8%, Endolimax nana in 2.2%, Entamoeba coli in 1% and cysts of Giardia intestinalis in 1.9% of cases. Appendicopathies associated with Enterobius were most frequent in the age group from 6 to 10 years (24.3%) and from 21 to 25 years (12.2%). Patients older than 15 years were practically women only. Dientamoeba was most frequent in the age group from 11 to 15 years (11.3%). In women D. fragilis was three times more frequent than in men. The coincidence of D. fragilis and E. vermicularis infections was 50%. No interactions were seen between the protozoans in the contents of the appendix and its mucous membrane. Statistical evaluation indicates possible etiologic role of E. vermicularis in the occurrence of acute appendicities. D. fragilis appears to be the most common intestinal protozoan parasite in Bohemia.     

侵染苜蓿的豇豆花叶病毒的研究

 从新疆苜蓿矮缩花叶病株上分离到一种病毒分离物G-14,在测定的9科40种植物中,此分离物可侵染6科19种植物,易由汁液摩擦接种,桃蚜(Myzus persicae)、豆蚜(Aphis craccivora)、棉黑蚜(A.atrata)和苜蓿无网长管蚜(Acyrthosiphon rondoi)等不传毒,可由首蓿叶象岬(Hypera variabilis)传毒;致死温度55~60℃,稀释限点10^-3~10^-4,体外保毒期21天;病毒粒体球状,直径约28nm。电镜观察病组织超薄切片,可见晶格状排列的病毒粒体。经琼脂双扩散血清学测定,该分离物与豇豆花叶病毒(CPMV)抗血清呈阳性反应。由此鉴定G-14为CPMV。提纯病毒经SDS-聚丙烯酰胺凝胶电泳测定有3个蛋白组分。分子量分别为44800,24500,22400道尔顿;琼脂糖电泳测得有二个核酸组分。     

Two new species of isospora (Apicomplexa: Eimeriidae) from geckoes of the genus Rhacodactylus (Sauria: Gekkonidae) endemic to New Caledonia

Coprological examination of New Caledonian geckoes of the genus Rhacodactylus Fitzinger, 1843 revealed two new species of coccidia. Isospora leachiani sp. n. from R. leachianus (Cuvier, 1829) has oval, colourless oocysts, measuring 21-26 x 16-18.5 microm. Sporocysts are ellipsoidal, 11-12.5 x 6.5-8 microm, with distinct Stieda and substieda bodies. Oocysts of Isospora sykorai sp. n. from R. ciliatus (Guichenot, 1866) are elongately oval to cylindrical, 20-23.5 x 11-14 microm; sporocysts of this species are ellipsoidal, 10-11.5 x 7-8 microm, with a slightly pointed end and Stieda and substieda bodies. Infected geckoes did not exhibit any alteration of their health status.     

Susceptibility of IFN-gamma or IL-12 knock-out and SCID mice to infection with two microsporidian species, Encephalitozoon cuniculi and E. intestinalis

Susceptibility of three strains of immunodeficient mice to two related microsporidian species Encephalitozoon cuniculi Levaditi, Nicolau et Schoen, 1923 and Encephalitozoon intestinalis (Cali, Kotler et Orenstein, 1993) was compared. While both, severe combined immunodeficient (SCID) and interferon-gamma knock-out (IFN-gamma KO) mice, succumbed to either intraperitoneal (i.p.) or peroral (p.o.) (natural) infection with both parasites, only i.p. infection with E. cuniculi killed interleukin-12 knock-out (IL-12 KO) mice. IFN-gamma KO mice died earlier than SCID mice. Adoptive transfer of naive splenocytes from IFN-gamma KO mice did not protect the SCID mice from a lethal infection with either of the Encephalitozoon species. However, reconstituted mice survived significantly longer (P<0.05), thus indicating the role of IFN-gamma produced by host NK cells in the development of mechanisms of anti-microsporidial protective immunity. Non-lethal outcome of the infection always correlated with the increase in CD8+ T lymphocyte subpopulation. Both E. intestinalis-infected IFN-gamma KO and IL-12 KO mice produced comparable levels of specific antibodies, suggesting that antibodies did not protect IFN-gamma KO mice from lethal infection.     

Differentiation of species of Eimeria from the fowl using a computerized image-analysis system

Oocysts of Eimeria species from the fowl have been identified using a computerized image-analysis system (Leitz T.A.S. Plus Image-Analyser). The system enabled semiautomatic measurement of oocyst dimensions with subsequent species of diagnosis based on graphic statistical evaluation of size and shape of measured parasites. E. mitis, E. acervulina, E. brunetti, E. maxima, E. tenella and complex of E. necatrix and E. praecox were distinguishable both in pure cultures and in mixtures. It was not possible to distinguish E. praecox from E. necatrix using this system.     

New species of Choleoeimeria (Apicomplexa: Eimeriidae) from the veiled chameleon, Chamaeleo calyptratus (Sauria: Chamaeleonidae), with taxonomic revision of eimerian coccidia from chameleons

Coprological examination of 71 samples from a breeding colony of veiled chameleons, Chamaeleo calyptratus Duméril et Duméril, 1851, revealed a presence of two species of coccidia. In 100% of the samples examined, oocysts of Isospora jaracimrmani Modry et Koudela, 1995 were detected. A new coccidian species, Choleoeimeria hirbayah sp. n., was discovered in 32.4% of samples from the colony. Its oocysts are tetrasporocystic, cylindrical, 28.3 (25-30) x 14.8 (13.5-17.5) microm, with smooth, bilayered, -1 microm thick wall. Sporocysts are dizoic, ovoidal to ellipsoidal, 10.1 (9-11) x 6.9 (6-7.5) microm, sporocyst wall is composed of two plates joined by a meridional suture. Endogenous development is confined to the epithelium of the gall bladder, with infected cells being typically displaced from the epithelium layer towards lumen. A taxonomic revision of tetrasporocystic coccidia in the Chamaeleonidae is provided.     

Morphological, developmental and ecological evidence for a progenetic life cycle in Neochasmus (Digenea)

Seven species of fishes, Catostomus commersonii (Lacépède), Etheostoma nigrum Rafinesque, Micropterus dolomieu Lacépède, Notemigonus crysoleucas (Mitchill), Notropis hudsonius (Clinton), Perca flavescens (Mitchill), and Percina caprodes (Rafinesque) from the St. Lawrence River, Quebec, Canada, were found infected with progenetic specimens of Neochasmus spp. in the orbits and/or the body musculature. Worms displayed varying degrees of maturation. Eggs occupied the entirety of the worm in late stages of development and persisted as distinct clusters in situ after worm death. Populations of parasites were studied monthly in E. nigrum from one site between May and October in order to follow parasite recruitment, development and maturation. Recruitment of parasites was observed in young-of-the-year fish primarily in July and continued through October. Worms matured rapidly, displaying egg production within a month. Later developmental stages, in which eggs occupied most of the worm, and clusters of eggs became abundant by September. Infections in overwintered fish collected in May consisted mainly of worms in early stages of egg production and of clusters of eggs. When hatched artificially, eggs from the clusters released viable miracidia, indicating that they survive beyond the lifespan of the adult worm. It is suggested that progenesis is a fixed characteristic of the life cycle of these species, that egg dispersal requires the death of the host and that it is facilitated by predation. All prior records of Neochasmus spp. are examined, leading us to conclude that the role of the putative definitive host (primarily basses) has been reduced to that of a dispersal agent. Current hypotheses concerning the evolution and maintenance of progenesis are considered, but it is concluded that they do not apply to this host-parasite system.     

An unusual localization of developmental stages of Cryptosporidium parvum Tyzzer, 1912 in the cells of small intestine of a gnotobiotic piglet

In a gnotobiotic piglet infected with 50.10(6) oocysts of Cryptosporidium parvum, developmental stages of the parasite were found in the duodenum, anterior jejunum and middle jejunum on the first day post infection (1 DPI). During the studies of the ultrastructure, trophozoites and meronts of C. parvum were encountered in the microvillous zone of enterocytes, and the outer membrane of parasites was a continuation of the membrane of microvilli. Unusual was the attachment of C. parvum trophozoite on the opening of a goblet cell, as well as a meront localized in the cytoplasm in the enterocyte of anterior jejunum. These findings show that C. parvum is very adaptive and capable of developing in a still undescribed location.