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PubMed1975

[Evolutive cycle of Paratimonia gobii, Prevot and Bartoli 1967 (trematoda-monorchiidea)].

The cycle of Paratimonia gobii PREVOT & BARTOLLI, 1967 (Trematoda-Monorchiidae), a parasite of Pomatoschistus microps (Teleostei gobiidae), has been discovered and carried out experimentally. The mollusc, first intermediary host, is Abra ovata (Lamellibranchiata, Scrobiculariidae). The gymnocephalous cercaria leaves the mollusc, then sucked in by the respiratory stream, becomes encysted in the inhaling siphon of another Abra. The accumulation of metacercaria results in the autonomy of this siphon and it is this cut-off organ which is becoming part of the alimentary chain of the final host allows the continuation of the cycle.

Animals↗
PubMed1994

A redescription and a new geographical record in the Black Sea of Bacciger israelensis Fischthal, 1980 (Trematoda: Fellodistomidae).

Bacciger israelensis Fischthal, 1980 (Trematoda: Fellodistomidae) was recorded from Boops boops (Perciformes: Sparidae) in Bulgarian Black Sea coastal waters for the first time. Re-examination of the morphology of B. israelensis showed some new details: Laurer's canal opens dorsally a short distance anterior to the excretory pore; seminal receptacle situated posterior to ventral sucker and ventral to ovary; ovary composed of three nearly spherical but not separated lobes forming apexes of isosceles triangle; tegumental spines covering body including entire surface of ventral sucker and distal half of upper part of oral sucker.

Animals↗
PubMed1977

Histochemical and thin layer chromatographic analyses of neutral lipids in metracercarial and adult Cotylurus sp. (Trematoda: Strigeidae).

Histochemical and thin layer chromatographic studies were made on neutral lipids of Cotylurus sp. (Trematoda) metacercariae obtained from Physa heterostropha snails and from adults grown in the upper ileum of the domestic chick. Oil Red O staining demonstrated neutral lipids in the intestinal lumina, eggs and vitellaria of adults, and the excretory system of metarcercariae. As determined by TLC, excysted metacercariae incubated in a non-nutrient salt solution excreted free fatty acids, sterols, and sterol esters into the medium. TLC analysis detected free sterols, free fatty acids and sterol esters in metacercariae and adullts, and triglycerides detected in adults were not found in metacercariae.

Animals↗
PubMed2003

Ultrastructure of pigmented and unpigmented photoreceptors in cercariae of Trichobilharzia ocellata (Plathelminthes, Trematoda, Schistosomatidae): evidence for the evolution of parasitism in Neodermata.

The lens-covered pigment cup ocelli in free-swimming cercariae of Trichobilharzia ocellata were re-examined and the differentiation of the lenticular elements was studied in cercariae still enclosed in sporocysts. Each eye consists of a single rhabdomeric sensory cell, a single cup cell harboring pigment granules and the lens. This lens is developed step by step by the fusion of numerous dark platelets not enclosed by a bordering membrane. The material is presumably proteinaceous. There is no evidence that the lenses are of mitochondrial origin. Besides the pigment cup ocelli, a special type of unpigmented rhabdomeric photoreceptor was discovered. Three unicellular photoreceptors arranged in a three-dimensional configuration exist. These light-sensing organs show a principle of construction similar to that of phaosomous photoreceptors. We hypothesize that both types of photoreceptors are relevant for distinct reactions in the host-finding behaviour of the cercariae. The special type of lensing in the pigmented eyes seems to be restricted to Trichobilharzia species, whereas the phaosomous-like receptors may be more widespread in members of the Schistosomatidae. The obvious absence of any mitochondrial lensing in T. ocellata, and probably all other species of the Digenea, may be correlated with the evolution of endoparasitism in the Trematoda.

Animals↗
PubMed2004

The comparative development of Echinostoma caproni (Trematoda: Echinostomatidae) adults in experimentally infected hamsters and rats.

The aim of the present study was to compare the development of Echinostoma caproni (Trematoda: Echinostomatidae) adults in two host species displaying different degrees of compatibility with this parasite. For this purpose, the variability in the worm recovery, egg output, and morphology of E. caproni adults during the course of experimental infections in hamsters and rats was analyzed. Student's t-tests and two-factor ANOVA analysis with the time post-infection and the host species as independent variables, and Bonferroni t-tests as post hoc analysis were used for the study. Worm recovery and egg output were host species dependent. The values were significantly higher in the worms established in hamsters than those in rats. The oral sucker area, pre-pharynx length, and pharynx area were the most conservative features, and no significant variability related to the host species was detected. In contrast, body area, collar width, esophagus length, cirrus sac area, ventral sucker area, ovarian area and anterior and posterior testicular areas were significantly higher in those worms collected from hamsters. Moreover, significant worm age-host species interactions were found for body area, ovarian area, ventral sucker area, and anterior and posterior testicular areas.

Animals↗
PubMed1994

Parasite infection and cancer: with special emphasis on Schistosoma japonicum infections (Trematoda). A review.

This article contains a review of current knowledge on the association of parasite infections and cancer formation, especially that of Schistosoma japonicum (Trematoda) in man and experimental animals. The association of S. haematobium infection and bladder cancer is well known and documented. However, S. japonicum infection has also been reported to be associated with cancer, in this case hepatocellular carcinoma and/or colorectal cancer. Pathological records and analyses have shown a correlation between this infection and cancer, and pathohistological descriptions have been numerous, together with clinical case reports. Epidemiological analyses have been conducted in China and Japan and support a role of S. japonicum infection as one of the risk factors in cancer formation, along with others, such as hepatitis virus infection and alcoholic intake. Experimental results have also shown that cancer appears early and in larger numbers in experimentally infected animals given a known carcinogen. In spite of these positive end-point associations, the mechanism of schistosome-mediated enhancement of carcinogenesis is obscure. A suggestive observation is that in S. japonicum-infected mice carcinogen-metabolizing hepatic activity including P-450 was decreased so that an administered carcinogen persisted for a longer period than in uninfected mice. Further studies, both epidemiological and experimental, are needed to firmly establish the relationship between schistosome infection and cancer.

Animals↗
PubMed1975

Nasitrema attenuata (Trematoda) infection of Tursiops truncatus and its potentialities as an aetiological agent of chronic pulmonary lesions.

Two cases of Nasitrema sp (Trematoda) infection of the bottlenosed dolphin, Tursiops truncatus, are reported and N. attenuata is briefly redescribed. The adults of the trematode occurring in the nasal sinuses and posterior nasal passage of the dolphins are considered as practically harmless for the host but thier eggs, aspirated deep into the bronchial tree, may initiate a foreign-body of inflammatory reaction in the lungs and continuous aspiration of such eggs may provoke a chronic pneumonia condition.

Animals↗
PubMed2001

Complete DNA sequence and gene organization of the mitochondrial genome of the liverfluke, Fasciola hepatica L. (Platyhelminthes; Trematoda).

The complete nucleotide sequence of the mitochondrial (mt) DNA molecule of the liverfluke, Fasciola hepatica (phylum Platyhelminthes, class Trematoda, family Fasciolidae), was determined. It comprises 14462 bp, contains 12 protein-encoding, 2 ribosomal and 22 transfer RNA genes, and is the second complete flatworm (and the first trematode) mitochondrial sequence to be described in detail. All of the genes are transcribed from the same strand. Of the genes typically found in mitochondrial genomes of eumetazoans, only atp8 is absent. The nad4L and nad4 genes overlap by 40 nt. Most intergenic sequences are very short. Two larger non-coding regions are present. The longer one (817 nt) is located between trnG and cox3 and consists of 8 identical tandem repeats of 85 nt, rich in G and C, followed by 1 imperfect repeat. The shorter non-coding region (187 nt) exhibits no special features and is separated from the longer region by trnG. The gene arrangement resembles that of some other trematodes including the eastern Asian Schistosoma species (and cyclophyllidean cestode species) but it is strikingly different from that of the African schistosomes, represented by Schistosoma mansoni. The genetic code is as inferred previously for flatworms. Transfer RNA genes range in length from 58 to 70 nt, their products producing characteristic 'clover leaf' structures, except for tRNA(S(UNC)) and tRNA(S(AGN)) lacking the DHU arm.

Animals↗
PubMed2000

Description of Acanthotrema armata n. sp. (Trematoda: Heterophyidae) from Larus audouinii (Aves: Laridae), with an amended diagnosis of the genus Acanthotrema Travassos, 1928.

Acanthotrema armata n. sp. (Trematoda: Heterophyidae) is described from the gut of Larus audouinii Payraudeau (Aves: Laridae) caught on the Chafarinas Islands in the southwestern Mediterranean (Spain). This trematode differs from other species of Acanthotrema Travassos, 1928 in having two spined, sclerotised pieces in the ventrogenital sac and in the position of the genital pore. Parastictodora Martin, 1950 is considered a synonym of Acanthotrema. As the diagnosis of the genus Acanthotrema was based only on its type-species, it is amended to include the characteristics of the new species and those attributed to Parastictodora.

Animals↗
PubMed1992

Study on the surface morphology of the developmental stages of the liver fluke, Opisthorchis viverrini (Trematoda: Opisthorchiidae).

The external morphology of some developmental stages of the fluke Opisthorchis viverrini (Trematoda: Opisthorchiidae), parasitizing humans in Southeast Asia was studied for the first time using electron microscopy. The surface structure of the egg, as well as the rediae, cercaria, metacercaria, and adult found in naturally infected hosts from Laos are described herein and their morphological characteristics discussed.

Animals↗
PubMedDate not supplied

The histopathology of Scomber japonicus infection by Nematobothrium scombri (Trematoda:Didymozoidae) and of larval anisakid nematode infections in the liver of Pagrus pagrus.

The histopathology induced by Nematobothrium scombri (Trematoda) in Scomber japonicus and of larval anisakid nematodes in Pagrus pagrus is described. Nematodes larvae occurred within the liver capsule and N. scombri occurred within nodules in the opercula. The fishes were collected off the coast of Rio de Janeiro State.

Animals↗
PubMed1992

Surface ultrastructure of Heterophyes nocens (Trematoda: Heterophyidae).

The surface ultrastructure of Heterophyes nocens (Trematoda: Heterophyidae) was studied by scanning electron microscopy(SEM). The adult worms were recovered from experimentally infected cats and from a naturally infected patient. They were leaf-like, ventrally concave, and ovoid or pyriform in shape. Ciliated knob-like sensory papillae (type I) were observed in single or grouped forms on and around the oral sucker, whereas non-ciliated round swellings (type II papillae) were seen on the lip of the ventral sucker. The tegumental spines around the oral sucker were 5-9 pointed, whereas those between the two suckers were 12-17 pointed. Ventrolaterally, three groups of 5-6 type I papillae were located between the oral and ventral suckers, with single ones alternating between them. The genital sucker was protruded or depressed, depending on the contraction state of the flukes, and the gonotyl spine number ranged 50-60. The number of tip points of tegumental spines was decreased posteriorly; finally they became 1-3 pointed. On the dorsal surface, 4 groups of 4-5 type I papillae were symmetrically located on both lateral sides, and the shape and distribution of tegumental spines were similar to those of the ventral surface. Although the tegumental ultrastructure of H. nocens was generally similar to those of other heterophyids, the genital sucker morphology including the number of gonotyl spines and/or the distribution pattern of tegumental spines and sensory papillae were suggested to be the characteristic features of H. nocens.

Animals↗
PubMed1992

Natural infections of Clinostomum complanatum (Trematoda: Clinostomatidae) in wild herons and egrets, Tottori Prefecture, Japan.

Nycticorax nycticorax, Ardea cinerea, Egretta garzetta, and Egretta intermedia were naturally infected with Clinostomum complanatum (Trematoda: Clinostomatidae) among fourteen wild herons, seven wild egrets and one wild bittern evaluated at the Veterinary Hospital of Tottori University, Tottori, Japan. The latter three species of heron and egrets are reported for the first time as definitive hosts of this parasite in Japan.

Animals↗
PubMedDate not supplied

[The use of the probability model for an estimation of a infection rate of White Sea mussels (MYtilus edulis) by Metacercariae Himasthla elongata (Trematoda: Echinostomidae) ].

A comparison of simple probability analytic model of infection rate depending on host's age with natural infection rate of mussels (Bivalvia: Mythilidae) with metacercariae Himasthla elongata (Trematoda: Echinostomidae) was carried out. Data on the natural rate of infection were accumulated during 3 years; 1152 individuals M. edulis were collected in two horizons within fucoid zone of the Kruglaya inlet and the Chupa inlet of the Kandalaksha bay (White Sea). A size of shell and number of H. elongata metacercariae were defined for each mussel using compressive dissection technique. The infection of mussels per year within our model is considers as independent evens: Pn = 1 - (1 - p)n, where n is the age of mussels, Pn is the theoretical part of infected n-year mussels, p is the probability of infection within one year. The probability of infection within year is assumed equal for every age of host. The estimate of probability of infection per year on the basis of sample of n-year's mussels was calculated as Pn = 1 - n square root of 1 - I(n), where n is the age of mussels, I(n) is the part of infected n-year mussels. The retransformed weighted average value of aresine-transformed p'n was used as p in our model (p = 0.3476). Statistically significant differences between empirical and theoretical (calculated from our models on the basis this value) infection rates were not found (P > > 0.05 chi 2-test). Moreover, statistical significant differences were absent (P > 0.05 Fisher exact test) in pairwise comparisons between empirical and theoretical infection rates for each age of mussels. The model does not take into consideration an effect of such factors as host's resistance, host's migration and increase of mortality in infected hosts. The absence of significant differences between the empirical and theoretical infection rates allows to suggest, that mentioned factors under the conditions of the Kruglaya inlet do not influence essentially onto infection of mussels with metacercariae H. elongata. This conclusions is in certain inconsistency with essential differences in such characteristic as an individual resistance of mussels to the infection with metacercariae H. elongata, detected in experiments in vitro (Gorbushin, Levakin, unpublished data). Analysis of intensity of the invasion of metacercariae H. elongata into mussels allows to suggest the existence of differential death rate of the hosts, which is exhibited in individuals over 7 years old. Studied example of mussels infected with metacercariae H. elongata under conditions of the Kruglaya inlet shows that the simple probabilistic model of the natural infection rate is usable for this kind of investigation. Our study also allows to conclude that in this case the infection rate of hosts is mainly determined by stochastic reasons. However, in some cases the probability of infection rate may not depend on the age and size of the host. The study of infection rate can not be used for analyses of individual differences of hosts in a resistance to parasites and an infection ability of the parasite.

Age Factors↗
PubMed1979

Thin-layer chromatographic analysis of phospholipids in Echinostoma revolutum (Trematoda) adults.

Thin-layer chromatographic analyses were made of phospholipids extracted from adult Echinostoma revolutum (Trematoda) and from the nonnutrient medium in which worms were maintained. Identity of phospholipids was based on comparison with authentic lipid standards and on specific chemical detection tests. The most abundant phospholipids in the extract were phosphatidyl choline, phosphatidyl ethanolamine and phosphatidyl serine; lesser amounts of cerebrosides and lysophosphatidyl choline were detected also. Phospholipids detected in the incubation medium were essentially as described for extracts.

Animals↗
PubMed1980

Microscopic pathology of liver of capuchin monkey (Cebus albifrons) infected with Athesmia foxi (dicrocoelidae : trematoda) : a pictorial illustration.

Histopathological changes in the livers of two white fronted capuchin monkeys, Cebus albifrons, associated with Athesmia foxi (Dicrocoelidae : Trematoda) infection are illustrated through photomicrographic plates. The lesions are confined in and around the hepatic biliary system. The bile ducts are greatly distended and thickened because of fibroblastic activity and collagen deposit in its walls. In one of the livers desquamative, necrotic and reorganizational changes are found to be well marked. At places the bile duct lumen contains infiltrating inflammatory cells and shed pieces of biliary epithelia mixed in a scanty necrotic tissue while elsewhere the necrotic changes are more pronounced and the bile duct contents are presented only by homogeneous amorphous debris. The overall picture is that of chronic cholangitis coupled with cholangiectasis.

Animals↗