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PubMed1982

Comparative migration, growth and development of Typhlocoelum cucumerinum sisowi in dabbling ducks and Typhlocoelum cucumerinum cucumerinum in diving ducks.

Experimental infections of mallards (Anas platyrhynchos L.) with Typhlocoelum cucumerinum sisowi (Skrjabin, 1913) and of canvasbacks (Aythya valisineria (Wilson)) with Typhlocoelum cucumerinum cucumerinum (Rudolphi, 1809) revealed significant differences in various parameters of the life-cycle in the definitive host. Both T. c. sisowi and T. c. cucumerinum migrate to the trachea via the abdominal cavity, air sacs and lungs, although T. c. cucumerinum migrate more quickly and more synchronously than T. c. sisowi. Typhlocoelum c. sisowi has a shorter expected life-span than T. c. cucumerinum but grows and reaches maturity more quickly than T. c. cucumerinum. Evidence suggests that T. c. cucumerinum has a higher fecundity than T. c. sisowi. These differences in the patterns of migration, growth and development are related not only to differences between the two host species but also to differences intrinsic to the parasites, and serve to provide biological support for considering them as separate sub-species.

Animals↗
PubMed2006

Diclidophora merlangi (Monogenea: Diclidophoridae) on Atlantic cod, Gadus morhua.

Diclidophora merlangi (Kuhn, in Nordmann, 1832), as species specific to whiting, Merlangius merlangus (Linnaeus, 1758), is reported and described for the first time on the gills of Atlantic cod Gadus morhua (Linnaeus, 1758). Of the about 1,200 cod examined in this article, only 2 specimens of D. merlangi occurred on 2 fish, suggesting that they represented accidental infections. The 2 specimens showed specific traits of D. merlangi, but their size was considerably smaller than that of D. merlangi on whiting. Principal-component analyses showed that the morphology of the specimens on cod was more similar to that of D. merlangi than those of other congeneric species from the North Atlantic, additionally supporting their assignment to D. merlangi. Quantitative data documenting the potential reproductive consequences of D. merlangi occurring on cod is also provided. The testes and germaria of the specimens on cod were noticeably smaller than those of D. merlangi on whiting, but the number of testes was similar and spermatozoa were observed in the sperm duct. By contrast, the aspect and smaller size of the oocytes suggested that D. merlangi on cod could not produce viable ova, although 1 specimen exhibited an egg with normal sized and shaped capsule.

Animals↗
PubMed2005

Population and seasonal distribution of Procamallanus daccai in Eutropiichthys vacha in Kaptai Lake, Chittagong, Bangladesh.

The population and seasonal distribution of Procamallanus daccai (Nematoda: Procamallanidae) in Eutropiichthys vacha (Siluridae) from the Kaptai Lake were studied for a period of 20 months during 1986-1987. A total of 208 fish were necropsied and 5652 worms were recovered, of which 2392 were from 87 infected male fish and 3260 were from 89 infected female fish. Prevalence values varied from 50% to 95%. The intensity and abundance of nematodes fluctuated over the study period and are statistically significant (F=14.87, P<0.0001), and showed a seasonal preference for the summer period (F=33.39, P<0.05). The mean intensity was the highest in the smallest size group at 66.3+/-12.7 which gradually decreased to 4+/-1.89 in the largest size group. No significant differences were found between parasites from male and female hosts, except in the summer. Male parasites were less abundant in the population. Female worms were grouped into immature, maturing and gravid and all these stages were present throughout the year. The highest occurrence of both immature and gravid P. daccai was found during the months of February to April each year. Peak recruitment seems to occur during this period due to the presence of high quantities of immature worms.

Animals↗
PubMed1995

Life history of the nematode Rhabdochona hellichi, a parasite of the barbel in the Jihlava River, Czech Republic.

From April 1992 until June 1993, the seasonal dynamics of Rhabdochona hellichi (Srámek, 1901) in its definitive host, the barbel (Barbus barbus), was studied in the Jihlava River (the Danube basin), Czech Republic. The parasite occurred in barbel throughout the year (overall prevalence 93% and intensity of infection 1-1384 [mean 78] nematodes per fish), but there were distinct seasonal fluctuations in prevalence and mean intensity values associated with the parasite's seasonal cycle of maturation. Prevalence was very high (usually 100%) during most months of the year, while lowest values were recorded in August and October. The highest values of mean intensity occurred in April. Both prevalence and mean intensity values increased with the body length of the hosts. The parasite exhibited a distinct annual cycle of maturation with egg-producing females present only from June until August, whereas larvae occurred in barbel mostly from September until April of the next year. Trichopteran (caddis-fly) larvae of the genus Hydropsyche (H. angustipennis and H. pellucidula) were found as natural intermediate hosts of R. hellichi (prevalence 4%, intensity 1-10 nematode larvae). The strictly seasonal maturation of this nematode may be associated with the temperature regime in the locality and seasonal cycles of maturation of its intermediate hosts.

Animals↗
PubMed2005

Mode of transmission, host switching, and escape from the Red Queen by viviparous gyrodactylids (Monogenoidea).

Compared to other monogenoidean groups, viviparous gyrodactylids exhibit extraordinary species diversity and broad host range. It has been suggested that this evolutionary success is associated with a suite of morphological and life-history traits that include, in part, continuous transmission (i.e., ability to infect new hosts throughout the gyrodactylid life cycle). Experiments were conducted to explore the putative adaptive advantage of continuous transmission within viviparous gyrodactylids during colonization of new host resources. Differences in infrapopulation growth, such as abundance, prevalence, and duration of the infection, of Gyrodactylus anisopharynx on 3 species of fish--Corydoras paleatus and Corydoras ehrhardti (both natural hosts) as well as Corydoras schwartzi (a host not known to harbor G. anisopharynx)--held under isolated and grouped conditions were determined. Results showed that infrapopulations of G. anisopharynx on C. paleatus and C. schwartzi had higher growth when the parasite had the opportunity for host transfer (grouped hosts). Infrapopulations of G. anisopharynx on isolated and grouped C. ehrhardti showed an opposite trend, although differences in mean duration and maximum abundance were not statistically different. Results obtained from experiments with C. paleatus and C. schwartzi support the hypothesis that continuous transmission in viviparous gyrodactylids enhances colonization success, probably by allowing initial avoidance of Red Queen dynamics. The absence of statistical differences between infrapopulations on isolated and grouped C. ehrhardti suggests that parasite dynamics may be influenced by factors other than continuous transmission in this host.

Animals↗
PubMed2006

Prevalence of Gymnophalloides seoi infection in coastal villages of Haenam-gun and Yeongam-gun, Republic of Korea.

One coastal village in Haenam-gun and two in Yeongam-gun, Jeollanam-do were surveyed for intestinal parasite infections by fecal examination. The egg positive rates of Gymnophalloides seoi were high, 24.1% (14/58) in Haenam-gun and 9.3% (11/118) in Yeongam-gun. The egg positive rates of heterophyids, including Heterophyes nocens, and of Clonorchis sinensis were 10.3% and 6.9% in Haenam-gun, and 14.4% and 8.5% in Yeongam-gun, respectively. After praziquantel treatment and purgation, a total of 37,761 fluke specimens were recovered from 17 patients; 11 in Haenam-gun and 6 in Yeongam-gun. Gymnophalloides seoi was the most commonly recovered species, with 37,489 specimens in total (2,205 per person). Other recovered flukes included Heterophyes nocens, Stictodora fuscata, Heterophyopsis continua, Pygidiopsis summa, and undetermined species. These results indicate that the areas surveyed are new endemic foci of G. seoi.

Adult↗
PubMed1984

[Studies on the zoonoses in Hokkaido, Japan. 6. Experimental human echinostomiasis].

Etiological analysis and parasitological examinations of human echinostomiasis were investigated. The four volunteers (case A, B, C and D) were orally administrated metacercariae harvested from the fresh water snails (Lymnaea japonica) experimentally infected with Echinostoma hortense eggs. Numbers of metacercariae administrated were 20 for cases A and B, 30 for case C and 50 for case D. Prepatent periods of four cases were 14 days (case D) and 17 days (cases A,B and C) after administrations. Patent periods of egg output were 18 days (case A), 32 days (case C), 207 days (case B) and 209 days (case D). The latter of two cases (B and D) showed the longest period of egg output in human echinostomiasis. Case A revealed the symptoms of violent watery diarrhoea and abdominal pain from 3rd to 4th weeks after administration, but others were asymptomatic. Maximal eosinophilia (22-35%) in peripheral blood of the three cases (cases A, C and D) was recognized 4 weeks after administration and the values decreased gradually thereafter. Case B did not show eosinophilia during the experimental period. Total serum IgE value measured by RIST method did not rise in all cases.

Adult↗
PubMed2005

Helicometra Odhner, 1902 (Digenea: Opecoelidae) in Australian waters: problems of species identification and a description of H. sprenti n. sp.

Helicometra Odhner, 1902 is reported from temperate Australian marine teleosts in which it appears to be rare. Of 285 species of fishes from 84 families examined, only 10 species from 9 families were infected. One infection, that in Platycephalus speculator caught from off the coast of Western Australia, is highly distinctive and the name Helicometra sprenti n. sp. is proposed for this species. The other infections were from members of the Antennariidae, Apogonidae, Kyphosidae, Labridae, Paralichthyidae, Pinguipedidae, Scorpaenidae and Sparidae, all from off southern Queensland and New South Wales. There is no evidence that infections are common in any of these hosts, which have little relationship to each other. Measurements and figures are presented for representatives from all the host species. Only minor variation was found in features such as body dimensions and the extent of the vitelline follicles, and it is concluded that the specimens probably represent a single species with a very low host-specificity. We suspect that the general scarcity of the worm is consistent with the presence of only one species, although the possibility that a species-complex is present cannot be ruled out. The specimens are broadly consistent with H. fasciata (Rudolphi, 1819), a species first described from Europe, and they are tentatively identified as this species, although it seems likely that ultimately they will prove to represent a different taxon. Determination of the ultimate identity of this form will require the application of molecular and life-cycle studies of worms from different hosts and localities.

Animals↗
PubMed2002

In vitro culture of the avian echinostome Himasthla elongata: from redia to marita.

Axenic primary cultures of Himasthla elongata rediae harvested from hepatopancreas of naturally infected marine prosobranch snail Littorina littorea were maintained in Leibovitz's L-15 medium (osmolarity of approximately 780 mOsm, pH 7.8, temperature 14 degrees C under normal atmospheric conditions). Cultured rediae were active, motile and demonstrated high synthetic activity in metabolic labelling experiment. Long-term cultivation experiment showed 50% survival level of the rediae for up to 70 days and significant differences between mortality in redia groups derived from different host individuals. Half of the rediae in the most robust group survived for up to 163 days, when the experiment was terminated. Development and emergence of in vivo preformed cercariae and daughter rediae was observed. Cercariae in the culture also encysted, transformed into metacercariae and some of them in one to two weeks after the transformation spontaneously excysted into juvenile maritae. The employed culture system is characterized by a very low level of proteolytic activity. This system is suggested as a method permitting to obtain rediae secretory-excretory products free of host-derived contaminants.

Amino Acids↗
PubMed1994

The first discovery of an endemic focus of Heterophyes nocens (Heterophyidae) infection in Korea.

A highly endemic focus of human infection with Heterophyes nocens (Heterophyidae) was discovered from a small coastal village of Shinan-gun, Chollanam-do, for the first time in Korea. Fecal examinations by cellophane thick smear and formalin-ether sedimentation techniques revealed 42.9% heterophyid egg positive rate out of 98 inhabitants examined. It was difficult to confirm the species of heterophyids only by eggs. In order to collect the adult flukes, the egg positive cases were treated with 10 mg/kg single dose of praziquantel and purged with magnesium sulfate, and the adult worms were collected from the diarrheic stools. From each of 18 cooperative patients 1 to 1,124 (total 4,730) H. nocens worms were recovered, together with a few to large numbers of heterophyids (Pygidiopsis summa, Stictodora fuscatum) and/or gymnophallids (Gymnophalloides seoi). It is speculated that H. nocens might be widely distributed along the southwestern coastal areas where the brackish water fish such as the mullets or gobies are popularly eaten raw.

Adult↗
PubMed1999

Trichobilharzia regenti, a pathogen of the avian and mammalian central nervous systems.

The development of nasal avian schistosomes of the genus Trichobilharzia in their final host is poorly known. Therefore, an experimental infection of ducklings (Anas platyrhynchos f. dom.) by T. regenti was performed. The infection resulted in leg paralysis and orientation/balance disorders of birds. The examination of the duck's spinal cord and brain confirmed the presence of developing parasites in pre-patent as well as patent periods. The absence of the worms in other tissues strongly supports our hypothesis that the parasite migrates through the central nervous system (CNS) to its final location in bird nasal mucosa. The injury level is probably dependent on number of parasites as well as yet unknown host factors. The affinity to the CNS seems to be high; also by exposure of experimental animals to low cercarial doses the growing worms in the CNS were found. In addition to the generally accepted view that bird schistosomes may cause cercarial dermatitis of mammals (including man), there is evidence of a partial development of T. regenti in mouse CNS; in certain cases leg paralysis was also recorded. Therefore, the pathogenesis spectrum caused by bird schistosomes in birds/mammals needs to be reconsidered.

Animals↗
PubMed2006

Density-dependent topographical specialization in Gyrodactylus anisopharynx (Monogenoidea, Gyrodactylidae): boosting transmission or evading competition?

Viviparous gyrodactylids are remarkable monogenoid ectoparasites, not only because of their speciousness, but also due to their unusually wide range of hosts. Although many factors have been proposed to determine the location where gyrodactylids attach to their hosts, little is known about how their preference for specific host body regions changes over the course of infection. In this study, we investigate the dynamics of topographical specialization of the parasite Gyrodactylus anisopharynx on 2 of its natural freshwater fish hosts (Corydoras paleatus and C. ehrhardti), as well as a naïve host (C. schwartzi). We recorded the spatial location of this parasite from the foundation of the infrapopulation to its extinction to assess how topographical specialization is affected by host species, the size and the age of the infrapopulation, and the possibility of transmission among hosts. Our results indicate that topographical specialization is negatively correlated with infrapopulation size and only marginally affected by infrapopulation age. Also, the degree of specialization was different among host species, but seemed unaffected by the possibility of transmission among hosts. Therefore, observed changes in spatial specialization of G. anisopharynx do not appear to represent adaptive responses to maximize their transmission. Rather, mechanisms such as increased competition and/ or local immune responses might cause parasites to occupy less favorable regions of the body of their hosts with increasing density.

Animals↗
PubMed2004

Cytogenetic and sequence comparison of adult Phyllodistomum (Digenea: Gorgoderidae) from the three-spined stickleback with larvae from two bivalves.

Due to the low informative value of available morphological characters, cytogenetic and molecular methods, based on rDNA sequencing, were used to characterize adult and larval stages of Phyllodistomum spp. Species studied have 18 chromosomes with comparable absolute and relative lengths. Conventional Giemsa staining and karyometric analysis revealed clear differences in chromosome morphology of larval Phyllodistomum spp. infecting two bivalve host species, Sphaerium corneum and Pisidium amnicum. However, karyotypes of adult P. folium from three-spined sticklebacks and larval stages from S. corneum appear almost identical both with respect to the relative lengths and centromeric indices of the corresponding chromosome pairs. The entire internal transcribed spacer (ITS) region (ITS-1, 5.8S and ITS-2) and the D1-D3 region of 28S gene were sequenced and compared. Again, sufficient differences were observed between larval Phyllodistomum spp., while adult P. folium and larvae from S. corneum showed a high level of similarity. So, both cytogenetic and molecular data support the suggestion that they represent developmental stages of the same species. The results were compared with published data obtained by cytogenetic and molecular studies on the other Phyllodistomum species. Differences revealed in karyotype and rDNA sequences leads to the conclusion that the cercariaeum of P. folium sensu Sinitsin, 1905 could not be regarded as the larva of adult P. folium from three-spined stickleback.

Animals↗
PubMed2003

[Case report. Treatment of the gillworm disease (Dactylogyrosis) of some South American cichlids and catfish].

The infection with gillworms (Dactylogyrus sp.) causes severe problems in the keeping and breeding of tropical ornamental fishes, e.g. Discus (Symphisodon aequifasciata). Treatment of gillworm disease with different drugs has been shown in the past to be insufficient. Therefore, the effectiveness of a long-term use of praziquantel was evaluated in ornamental fish. Cumulative doses up to 10 mg praziquantel/l water were tolerated without side-effects by Angel Fish (Pterophyllum scalare), Discus, and a variety of catfish species (Ancistrus sp., Corydoras sp.). It was found appropriate to start with a dosage of 2.5 mg/l and to add the same dosage every other day several times. All adult parasites and larvae were killed by this treatment. For the complete elimination of the Dactylogyridae-population in a closed aquarium system, 3 therapy-cycles (duration: 5-6 d, accumulated dosage: 2.5 mg/l/d) prooved to be effective. It was important to interrupt the therapy-cycles with intervals without medication (1 to 4 weeks).

Animals↗
PubMed2004

Qualitative risk assessment of routes of transmission of the exotic fish parasite Gyrodactylus salaris between river catchments in England and Wales.

Gyrodactylus salaris is a freshwater, monogenean ecto-parasite of Atlantic-salmon. Infection of its natural host, the Baltic strain of Atlantic-salmon, is inapparent. G. salaris also can infect rainbow-trout (Oncorhynchus mykiss) permanently, and cause infection of < or =50 days in several other species. It is only on Atlantic stocks of Atlantic-salmon (Salmo salar) that the parasite multiplies unchecked by an immune response, causes death in juveniles and dramatic reductions in wild populations. In Norway, the parasite has been introduced into 45 rivers, resulting in reductions in Atlantic-salmon stocks of up to 98%. It is probably the most-important exotic fish-disease threat to the UK. We used risk analysis to assess the most-important routes of spread for G. salaris between rivers in England and Wales. The movement of live rainbow-trout was identified as the most-important route of transmission; this route is likely to lead rapidly to the wide geographic spread of the parasite. The movement of other species of fish (especially from sites holding rainbow-trout) is also an important risk. Other routes of spread (including mechanical transmission on farm equipment and vehicles, angling equipment, canoes, etc.) might allow limited local spread (mainly to neighbouring rivers).

Animals↗
PubMed1992

Ultrastructural features of the tegument of adult Cynodiplostomum azimi (Trematoda:Digenea) in experimentally infected albino rats.

The ultrastructure of the tegument of adult Cynodiplostomum azimi and the lesions caused by the worm at this host parasite interface in albino rats are described. The tegument consists of a syncytial distal cytoplasm (approx. 2.01-3.1 microns in thickness), bounded by an outer apical plasma membrane and an inner basal trilaminated lamina. The subtegumental cells (approx. 10.34 microns in length) are connected with the distal cytoplasm by means of cytoplasmic trabeculae. The morphology of the tegument appeared very variable. Large areas were formed of irregular folds, while other areas carried finger-like or papilla-form structures. Tegumental spines appear to have a crystalline lattice structure. Three morphologically distinct types of membrane-bound inclusion bodies were described in the tegumental/perikaryal complex. The electron-lucent elongate bodies (approx. 0.23 micron in length) were the predominant first type. The second was round-ovoid bodies (average length 0.12 micron) with a central core of electron-dense material. The third was electron-dense, rod-like in shape (0.28 micron in length) and occurred occasionally. The majority of these inclusion bodies were oriented parallel to the tegumental surface. The host's mucosa at the parasite interface showed marked flattening and partial to complete loss of mucosal microvilli. Inflammatory cells, particularly eosinophils were observed at the host-parasite interface.

Animals↗
PubMed2003

Unitubulotestis sardae (Trematoda: Didymozoidae) infection in Atlantic bonito Sarda sarda (Perciformes: Scomberomoridae) in the Ionian and Tyrrhenian Seas: histopathological and SEM investigations.

Nematobothrinae are trematoda digenea that usually live in cysts in fish tissues. They have been reported in different teleost species although the host-parasite relationships remain to be elucidated. This report is aimed at analysing the presence of Unitubulotestis sardae in the Atlantic bonito (Sarda sarda) populations fished in the Straits of Messina. The histopathological change reported in literature in similar cases is an aneurisma verminosa saccata, whereas, in the specimens here described, we show neovascularisation and at the same time, hyperplasia of the gill epithelium, leading to the formation of a bistratified cystic wall. The SEM examination of the parasitic cysts gave us a better understanding of the surface microanatomical details of the cystic walls. The external surface appeared to be constituted by a pluristratified covering epithelium of the gill arch. The internal layer was constituted by a net of blood vessels richly anastomosed with those originating from the gill arch arteries. This could be in agreement with data reported by Grabda (1947) on the localisation of the juvenile stages of the parasite in this blood vessel, but the evolution in cysts formation does not show similarities with the formation of an aneurisma.

Animals↗
PubMed2005

A new genus and species of cyclocoelid from the black-necked stilt, Himantopus mexicanus (Recurvirostridae), from Galveston, Texas.

Two black-necked stilts, Himantopus mexicanus (Recurvirostridae), from the Texas Gulf coast, died while in the care of bird rehabilitators and were found to be infected with Neoallopyge americanensis n. gen., n. sp. Neoallopyge n. gen. (Digenea: Cyclocoelidae) differs from Allopyge in having the testes situated some distance from the posterior extremity, 2 uterine loops on each side extensively invading the space posterior to the testes, no intertesticular uterine loops, and it is a parasite of Recurvirostridae in the western hemisphere rather than Gruidae from the Old World. The new species is unlike Allopyge antigones, Allopyge ominosus, and Allopyge undulatus in having the genital pore located anterior to the cecal bifurcation rather than posterior to it, and it is unlike A. ominosus and A. undulatus, where the uterus is entirely intercecal in having the uterine loops extending laterally, reaching the body wall on both sides. The new species further differs from A. antigones, A. ominosus, and Allopyge skrjabini in having larger eggs (148 [140-155] microm by 55 [45-63] microm compared with 95 by 55 microm, 65-80 by 40-46 microm, 119-124 by 55-66 microm, respectively), and it differs from Allopyge adolphi and A. undulatus in having narrower eggs (154 by 75 microm, 144 by 86 microm, respectively).

Air Sacs↗