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Histochemical studies of enzyme activities and structural elements in Gyrodactylus derjavini Mikailov, 1975 parasitizing fins of Oncorhynchus mykiss Walbaum were conducted. Marked activities of non-specific esterase, acid phosphatase, alkaline phosphatase and amino-peptidase were found in the intestinal caeca of the parasite. A strong activity of acetylcholinesterase was seen in the nervous system. Extraintestinal non-specific and eserine-sulphate resistant esterase was localized in the distal part of the hamulus sheath. Activities of peroxidase and glucuronidase were not detected. In the embryo, developing hamuli were enclosed in a sheath rich in phospholipids. Deposits of neutral lipids were sparse. The fully developed ventral and dorsal hamulus bars stained strongly for calcium. Lectin binding assays showed a mannose rich region in the cephalic duct openings, strong reactions for galactose in the glycocalyx whereas reactions for lactose were weak. These findings are discussed with respect to the parasite-host relationship.

A new species of myocoptid mite, Trichoecius calomysci sp. n. (Acari: Myocoptidae), from Calomyscus sp. (Rodentia: Cricetidae) from Iran is described.

Three species of cichlid fish, Tilapia brevimanus Boulenger, 1911, T. buttikoferi (Hubrecht, 1881), and T. cessiana Thys van den Audenaerde, 1968, from Guinea, Ivory Coast and Sierra Leone (West Africa) were examined for gill parasites for the first time. Six species of Monogenea were found of which one, Cichlidogyrus digitatus Dossou, 1982, had been previously described. Five new species, all belonging to the genus Cichlidogyrus Paperna, 1960, are described herein: C. albareti sp. n., C. hemi sp. n., C. nuniezi sp. n., C. bonhommei sp. n., and C. slembroucki sp.n.

Relatively few effective compounds are available for treating microsporidiosis in humans. In this study, several compounds were assayed for activity against Encephalitozoon intestinalis (Cali, Kotler et Orenstein, 1993) and Vittaforma corneae Shadduck, Meccoli, Davis et Font, 1990 in vitro. Of the benzimidazoles tested, albendazole was most effective and the MIC50 values were 8.0 ng/ml and 55.0 ng/ml for E. intestinalis and V. corneae, respectively. Fumagillin and its analogue, TNP-470 were nearly equally effective against both E. intestinalis and V. corneae. The MIC50 values of fumagillin were 0.52 ng/ml and 0.81 ng/ml, and the MIC50 values of TNP-470 were 0.35 ng/ml and 0.38 ng/ml for E. intestinalis and V. corneae, respectively. In addition, 12 of 44 purines and pteridines with putative tubulin binding activity that were synthesized at Southern Research Institute (SRI), inhibited microsporidial replication by more than 50% at concentrations that were not toxic to the host cells. Several chitin synthesis/assembly inhibitors inhibited growth of the microsporidia in vitro but were toxic for the host cells making it difficult to interpret the results. One exception was lufenuron, which caused no significant toxicity to the host cells and expressed approximate MIC50 values of 2.95 µg/ml and 6.3 µg/ml against E. intestinalis and V. corneae, respectively. These results warrant further studies on albendazole, fumagillin, TNP-470, lufenuron, and the selected SRI purines and pteridines for developing therapeutic strategies for microsporidiosis.

A series of laboratory experiments was conducted to investigate the possibility of post-cyclic transmission in Pomphorhynchus laevis (Müller, 1776). Rainbow trout Oncorhynchus mykiss (Walbaum) were exposed to P. laevis in naturally infected Cottus gobio Linnaeus, Noemacheilus barbatulus (Linnaeus), Phoxinus phoxinus (Linnaeus) and Leuciscus cephalus (Linnaeus) and sacrificed one month after infection. Post-cyclic transmission was possible from all four species even though they came from three families and differed in respect of their status and suitability as hosts of P. laevis. There was no selection for or against either sex of P. laevis, parasites grew in the rainbows and they occupied the same, normal site in the intestine of rainbows irrespective of source host. Post-cyclic transmission of gravid parasites could occur from C. gobio but not from L. cephalus. It is believed that this failure to transmit larger parasites of either sex reflects the age and so development of the proboscis bulb of P. laevis and the extent of the host encapsulation response rather than size or stage of maturity per se. Post-cyclic transmission has the potential to be important in nature.

Spermiogenesis in Phyllobothrium lactuca Beneden, 1850 begins with the formation of a differentiation zone bordered by cortical microtubules and containing a nucleus and two centrioles separated by an intercentriolar body and disposed one in the prolongation of the other. Later, formation of flagellar buds, striated roots and a median cytoplasmic extension takes place. Each centriole gives rise to a flagellum that rotates and fuses with the median cytoplasmic extension. At this stage, arched membranes appear at the front of the differentiation zone. The nucleus elongates, becomes filiform and migrates between the striated roots into the spermatid. After the migration of the nucleus, the old spermatid separates from the residual cytoplasm by strangulation of the ring of arched membranes. Absence of striated roots, right at the beginning of spermiogenesis has never been described before in the Tetraphyllidea. Likewise, centrioles made up of doublets of microtubules and spermatids with two axonemes have never been reported before during spermiogenesis of a Phyllobothriidae. In this work we show, for the first time, the existence in cestodes of thick-walled microtubules surrounded by a layer of electron-dense material. In addition, we describe, for the first time, the existence of an accumulation of electron-dense granules around striated roots and an hour-glass-shaped constriction at the anterior extremity of a median cytoplasmic extension in a platyhelminth.

Intestinal microsporidiosis was documented by detecting abundant slightly curved spores (2.9 × 1.2 µm) in the faeces of five of twelve skinks Mabuya perrotetii Duméril et Bibron, 1839 that originated from Ghana. Clinically, the microsporidiosis was characterized by decreased appetite, diarrhea, and weight loss. Histopathological changes consisted of villous atrophy, blunting of mucosa and flattening of individual epithelial cells in the large intestine. The ultrastructure of microsporidian spores was consistent with an Encephalitozoon species. The PCR-RFLP assay and the heteroduplex mobility shift analyses were used to verify that the skink microsporidian is a species of the genus Encephalitozoon Levaditi, Nicolau et Schoen, 1923 and indicate that this microsporidian is not E. hellem, E. intestinalis or a strain of E. cuniculi. The microsporidia in African skink represent an Encephalitozoon species morphologically identical to Encephalitozoon lacertae Canning, 1981.

The role of microtubules in the secretory processes in the tegument of adult trematode Fasciola hepatica L. is studied by estimating the effects of colchicine, a substance known to disrupt microtubules, on the number of T2 vesicles. Tissue slices of the worm are incubated in Hedon-Fleig medium with or without 5 x 10(-4)M colchicine. The dynamics of the colchicine-provoked secretory block is examined by morphometry on samples processed for electron microscopy. T2 vesicles are estimated as a total number or separately within three levels (apical, sub-apical and central) of the distal tegument. The secretory block is demonstrated as reduction in the total number of T2 vesicles. The separate counting within three levels of the distal tegument demonstrates in control samples a trend of sub-apical condensation of T2 vesicles. This pattern of T2 distribution remains unchanged in colchicine-treated samples in spite of the reduction of the mean T2 counts within each of the levels examined. The data illustrate the role of microtubules in both the tegumental transport of secretory vesicles and the stratification of the organelles within the tegument.

Stages of the life cycle of Ascocotyle (Phagicola) angeloi Travassos, 1928 were experimentally obtained, from cercariae from naturally infected Littoridina castellanosae (Gaillard) collected in artificial ponds in the Zoological Garden of Buenos Aires. Metacercariae were found encysted mainly in muscles and ovary, but also in other parts of the body of naturally and experimentally infected fish Jenynsia lineata (Jenyns) (Atheriniformes: Jenynsidae). Adults were obtained experimentally from chicks and mice. Ascocotyle (Phagicola) angeloi, redescribed in the present paper, is distinguished from other species of the subgenus by the two rows of oral spines, each with 14 spines. The characteristics of the studied cercaria corresponds to those of the subgenus Phagicola.

Faecal examination of the long nosed vine snake Ahaetulla nasuta Lacépède, 1789 revealed two species of caryosporan coccidia. The morphology of one species fits well with a description of Caryospora ahaetullae Modrý et Koudela, 1994, the second is a previously undescribed species. Oocysts of Caryospora veselyi sp. n. were spherical, 18.9 (16.5-21.5) µm in diameter, with pitted and brownish oocyst wall about 1.5 µm thick. An irregular polar granule about 2.0 × 1.0 µm was observed in 35% of the oocysts examined. Sporocysts were octozoic, ovoidal to ellipsoidal, 13.7 (13.0-15.5) × 10.3 (9.0-11.0) µm with a shape index 1.3 (1.2-1.4). Stieda and substieda bodies were present. Sporocyst residuum was present as small granules of irregular size scattered among sporozoites. Both species sporulated within 72 hours. The infected snake did not show clinical signs of disease.

Sphingolipids are a diverse and ubiquitous group of lipids. They are widely distributed in parasites and a number of novel forms have been described. Sphingolipid synthesis has been investigated in the malarial parasite, cestodes, digeneans and nematodes. Although there are differences in detail, the synthetic pathways involved are similar to those found in mammals.

Unikaryon montanum sp. n. infects the fat body, muscle, Malpighian tubules and ovaries of adult Ips typographus L. The development is haplokaryotic, with separate nuclei during the schizogony and sporogony. Sporonts have the cellular envelope with added layer of electron dense material. Two types of spores are formed: small broad-oval primary spores, 1.5 × 1.0 µm, with warty surface of spore wall, uninucleate, with isofilar polar filament in 5/6 coils and elongated-oval environmental spores, 0.8-1 × 2 µm, with warty spore wall attenuated at the anterior end, uninucleate, with spore polar filament in 8 coils. Both types have a dual polaroplast with the anterior part of a layer of confluent fine lamellae ending posteriorly in bulbous processes, and posterior part composed of coil of tubules.

A new Cryptosporidium species, C. saurophilum, is described from Schneider's skinks Eumeces schneideri Daudin, 1802. Oocysts were fully sporulated in fresh faeces and measured 5.0 × 4.7 µm (4.4-5.6 × 4.2-5.2 µm). The new species differs from C. serpentis Levine, 1980 by having smaller oocysts, developing in a different location of intestine, and by the inability to infect snakes.

The sera of 67 HIV-infected persons without clinical signs of Toxoplasma gondii infection and sera of 777 immunocompetent persons from three distinct regions of Czechoslovakia were examined for the presence of toxoplasmic antibodies using the complement-fixation test (CFT). Additionally Toxoplasma positive HIV+ individuals were re-examined for the presence of IgG and IgM toxoplasmic antibodies by ELISA methods. Results show that overall prevalence of toxoplasmic antibodies is not significantly greater in HIV-positive subjects (29.8 %) than in the general population (26.1 %). Similarities between these two tested groups were also documented by a close correlation of their geometrical means of titres (13.9 versus 14.5). All 20 HIV-infected patients who were positive in CFT were positive in ELISA IgG reaction, and none in ELISA IgM reaction. The detected antibody levels were suggestive of a latent Toxoplasma infection only. But because of the risk of the infection reactivation all of these patients should be attended to on a systematic basis.

The pathogenicity of the coccidium Isospora suis was studied in 42 conventional and 26 gnotobiotic piglets at 1-13 days post infection (DPI). The prepatent period of the coccidium I. suis was 4.5-5 days. Only in one experiment in conventional piglets the prepatent period of 3.5 days was recorded. At least 9 days pathogenesis of I. suis was recorded during which double alteration of the small intestine occurred. The first alteration was found at 3-4 DPI. The second phase of alterative changes was observed at 8-9 DPI. In comparison with gnotobiotic piglets in conventional piglets clinical signs and pathological changes used to appear one day sooner but reparation and regeneration of alterative changes was quicker. In the first phase of the infection (3-7 or 8 DPI) the heaviest pathological changes were in the posterior jejunum. In the second phase of the infection (8 or 9-12 DPI) the heaviest changes were in the middle jejunum. In short period repeated lesions of mucosal barrier of the small intestine multiply the pathogenicity of I. suis and rank I. suis in front place among other enteropathogens of nursing piglets.

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.

A total of 2,883 foreign students at the age of 18-30 years were examined for amoebiasis after their arrival to Czechoslovakia. Stool examinations revealed the presence of Entamoeba histolytica in 112 of them (3.9%). Students from 38 countries were found to be infected with this parasite. In a set of 2,064 students from these countries E. histolytica prevalence in stool was 5.4%. There were greater differences in the prevalence between individual countries inside a geographical region than between individual geographical regions. The highest E. histolytica prevalence in stool was found in students from tropical and southern Africa (6.7% of 745 examined) and the lowest in students from South-eastern Asia (3.1% of 321 examined). In a simple cross-section study, antibodies against E. histolytica were detected by enzyme-linked immunosorbent assay (ELISA) in the sera of 1,001 persons. Antibodies were detected in 7.9% of students at the following titres: 1:200 in 4.5%, 1:600 in 1.5%, 1:1,800 in 1.9%. Antibodies occurred more frequently in students carrying E. histolytica cysts (X2 = 14.9). Titre of ELISA antibodies in patients with confirmed liver abscess was higher than 1:1,800. counterimmunoelectrophoresis (CIEP) test was used for serum examinations of patients who had been demonstrated by ELISA to be seropositive and of those carrying E. histolytica cysts. In a set of 170 patients CIEP antibodies were also more frequent in those carrying E. histolytica cysts (X2 = 26.95). A comparison of the results of ELISA and CIEP tests in the same patients revealed that CIEP antibodies were more dependent on the actual parasitization with E. histolytica than ELISA antibodies.(ABSTRACT TRUNCATED AT 250 WORDS)

A total of 26,478 ixodid ticks (935 pools) were examined by intracerebral inoculation of suckling mice. Six species of ticks were tested: Ixodes ricinus (23,470 individuals), I. trianguliceps (12), Haemaphysalis punctata (831), H. concinna (39), Dermacentor reticulatus (69) and D. marginatus (2,057). The ticks were collected largely by flagging vegetation, a substantial minority (4%) from animals. Three strains of Francisella tularensis were isolated, one each from I. ricinus (males, district Breclav, southern Moravia), D. reticulatus (males, district Breclav) and D. marginatus (engorged females collected from sheep in Roznava district, eastern Slovakia). D. marginatus and D. reticulatus represent new vector species for Czechoslovakia.

The geographical distribution and host specificity of ectoparasites of Australian bream, Acanthopagrus australis (Gunther), A. butcheri (Munro), A. berda (Forskal) and A. latus (Houttuyn) are discussed. A total of 48 species of ectoparasites are recorded, i.e. 25 species of Copepodal 15 or Monogenea, 2 of Branchiura, 5 of Isopoda, and 1 of Hirudinea. Most parasite species have a wider geographical range than their main host species and do not conform to the zoogeographical regions established for free-living species. The monogeneans are host specific to the genus Acanthopagrus though they are commonly found on more than one species. Udonella has been recorded from caligid copepods on species of two families of teleost fishes in Australia. The copepods are less host specific than the monogeneans.

The present study was designed to test the susceptibility of free living rodents, viz Apodemus flavicollis, Microtus arvalis, Clethrionomys glareolus, Mus musculus, and outbred white mice from Dobra Voda farm, CSFR, to Coxiella burnetii, rickettsiae of the spotted fever group (Rickettsia sibirica, R. conorii, R. slovaca and R. akari) and rickettsiae of typhus group (R. typhi and R. prowazekii) by various routes of administration. The highest levels of antibodies to C. burnetti were found in A. flavicollis and M. arvalis inoculated intraperitoneally and intracerebrally. Antibodies to C. burnetii exerted peak levels between days 13 and 16 in contrast to white mice which showed maximum levels on day 28. When 10(0.5) and 10(0.05) EID50/0.25 ml of C. burnetii was administered intraperitoneally to A. flavicollis, M arvalis and white mice, the agent was detected only in organs of wild animals. In addition to spleen, the bone marrow appeared as a predilective tissue for the detection of this agent. R. akari at a dose of 10(4.5) EID50/0.25 ml caused overt illness and death in rodents. Antibody levels to R. sibirica and R. conorii were dependent on dosage, route of inoculation and duration of infection, but were not dependent on animal species. Antibodies to R. slovaca and R. akari were dependent on dosage, infection duration and animal species but were not dependent on the route of infection. For R. conorii, R. sibirica and R. slovaca a sharp increase of antibody levels with high titres on days 4-6 and peak levels about day 11 post intraperitoneal infection was characteristic. Antibody level to R. akari increased up to day 2 1. Spotted fever group rickettsiae in rodents inoculated intraperitoneally were observed in various organs, particularly in tunica vaginalis and spleen at days 2-8 post infection. R. typhi at a dose of 10(4.3) EID50/0.25 ml inoculated intracerebrally or intraperitoneally killed white mice and inoculated intraperitoneally killed C. glareolus and M. musculus. The antibody response of white mice to intraperitoneal, subcutaneous or intranasal inoculation of this rickettsia was low and no antibody was detected following peroral administration. M. musculus did not develop antibodies after intracerebral, intranasal, subcutaneous or peroral inoculation of R. typhi. The target organs for this rickettsia were the spleen and tunica vaginalis. R. prowazekii inoculated intraperitoneally into white mice at a dose of 10(6.5) EID50/0.25 ml and at a dose of 10(4.5) EID50 into C glareolus was fatal for these rodents. Following intraperitoneal inoculation of 10(2.3) and 10(4.2) EID50, this agent was not detected in both rodent species and the difference in antibody response between them was not significant in the infection duration but was evident with various doses of inoculated rickettsiae. Titres of rickettsiae measured by antibody response of intraperitoneally inoculated rodents and by the presence of agents in yolk sacs of chicken embryos showed 1 log unit higher values in rodents inoculated with C. burnetii and about 1-3 log units higher levels in rodents inoculated with R. sibirica and R. conorii. The titres of R. slovaca were almost the same in both substrates while R. akari reached the highest titres in white mice, lower in wild rodents and the lowest in yolk sacs. No si