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PubMed2006

Ecology of Clinostomum complanatum Rudolphi, 1814 (Trematoda: Clinostomidae) infecting fish from the floodplain of the high Paraná River, Brazil.

The prevalence of Clinostomum complanatum Rudolphi, 1814 (Digenea, Clinostomidae) in fishes Loricariichthys platymetopon, Parauchenipterus galeatus and Hoplosternum littorale, which are second intermediate hosts, was studied at the floodplain of the high Paraná River, Brazil. Season (alternation flood-drought), habitat (lentic and semi-lotic), and sex were not related to its prevalence. For L. platymetopon, the immature and smaller fish had the lowest prevalence, whilst the opposite was observed for P. galeatus and H. littorale. This suggests that the probability of being predated is unchanged by parasitism for L. platymetopon; thus, a cumulative effect of repeated infections is observed; for the two other species, the highest parasitised fish may have higher predation mortality rates. While H. littorale is the preferred item in birds' diet, L. platymetopon is the most abundant fish species and has the highest C. complanatum prevalence, which makes it the most likely path of transmission to the bird, the definitive hosts of C. complanatum.

Animals↗
PubMed2004

[Statistical models for spatial analysis in parasitology].

The simplest way to study the spatial pattern of a disease is the geographical representation of its cases (or some indicators of them) over a map. Maps based on raw data are generally "wrong" since they do not take into consideration for sampling errors. Indeed, the observed differences between areas (or points in the map) are not directly interpretable, as they derive from the composition of true, structural differences and of the noise deriving from the sampling process. This problem is well known in human epidemiology, and several solutions have been proposed to filter the signal from the noise. These statistical methods are usually referred to as Disease Mapping. In geographical analysis a first goal is to evaluate the statistical significance of the heterogeneity between areas (or points). If the test indicates rejection of the hypothesis of homogeneity the following task is to study the spatial pattern of the disease. The spatial variability of risk is usually decomposed into two terms: a spatially structured (clustering) and a non spatially structured (heterogeneity) one. The heterogeneity term reflects spatial variability due to intrinsic characteristics of the sampling units (e.g. igienic conditions of farms), while the clustering term models the association due to proximity between sampling units, that usually depends on ecological conditions that vary over the study area and that affect in similar way breedings that are close to each other. Hierarchical bayesian models are the main tool to make inference over the clustering and heterogeneity components. The results are based on the marginal posterior distributions of the parameters of the model, that are approximated by Monte Carlo Markov Chain methods. Different models can be defined depending on the terms that are considered, namely a model with only the clustering term, a model with only the heterogeneity term and a model where both are included. Model selection criteria based on a compromise between degree of complexity and goodness of fit are then needed to discriminate among them, because each specification has a different biological meaning. Our aim is to demonstrate that these techniques can be used to study the geographical distribution of a parasite infection. Our analyses are based on data collected in 142 farms of the province of Latina. In each breeding a fixed number of sheeps has been sampled (20) and checked for the presence of C. daubneyi. We have specified a Binomial model for the proportion of infected animals in each breeding. The heterogeneity component is modelled in a standard way, while we have used different prior specifications for the clustering term to show how they affect the results. When we use the usual specification also for clustering, the two models show a completely different spatial pattern of infection, probably because the intrinsic spatial structure of the clustering term tend to bias our inferences. The selection criterion indicates in this case the heterogeneity model as the "best" one. However, if we modify the prior so that a lower degree of spatial interaction is assumed, the clustering model is less complex and its goodness of fit better and it should be preferred.

Animal Husbandry↗
PubMed1991

Strigea falconispalumbi (Trematoda: Strigeidae): argentophilic structures of the miracidium.

A study of the argentophilic structures of the miracidium of the strigeid digenean Strigea falconispalumbi VIBORG, 1795 was carried out. Miracidia were hatched under laboratory conditions from eggs obtained from adult S. falconispalumbi from the intestine of a naturally infected Buzzard (Buteo buteo). Miracidia were stained with 0.5%. Silver Nitrate solution using standard techniques. The epidermal plates of the miracidium are arranged in four tiers according to the formula (6 + 8 + 4 + 3) = 21. The terabratorium bears 20 papillare. Papillae are also present at the bases of the epidermal plates of the first tier, and also at the margins of the terabratorium between the epidermal plates. The two pores of the excretory ducts are positioned laterally between the third and fourth tiers of epidermal plates.

Animals↗
PubMedDate not supplied

[Characteristics of the localization of Ancyrocephalus paradoxus (Monogenea) on the pike perch Stizostedion lucioperca].

In one summer old fishes of the pike perch, caught in the K urish Gulf of the Baltic Sea in August-September of 1984, at 100% infection with A. paradoxus 94% of monogeneans were localized under the lower anterior angle of the operculum on the lateral surface of the intergill space (isthmus). In fishes 1+ on the isthmus there were found 52%, in pike perches 2+ 42%, and in fishes 3+ 67% of worms. In older fishes (4-10+) the number of worms on the isthmus accounts for 5% of their total number while others are localized on gill filaments. Variability of sizes, chitinoid structures and microlocalization of worms depending on the age of fish were established.

Animals↗
PubMed2002

The use of host specificity, pathogenicity, and molecular markers to differentiate between Gyrodactylus salaris Malmberg, 1957 and G. thymalli Zitnan, 1960 (Monogenea: Gyrodactylidae).

The validity of Gyrodactylus thymalli has been questioned, based on its morphological and genetic resemblance to G. salaris. This taxonomic problem has practical implications regarding correct diagnosis of G. salaris, which has proved to be highly pathogenic to stocks of wild Norwegian Atlantic salmon. The host specificity and pathogenicity of G. salaris and G. thymalli were experimentally tested on salmon and grayling. Both parasite species were able to infect, live and reproduce on both fish species. G. salaris was highly pathogenic for the experimental stock of salmon, while grayling mounted an effective response against this parasite. Both fish species responded to an infection with G. thymalli. The results did not support the hypothesis of conspecificity between G. thymalli and G. salaris. The ribosomal RNA gene intergenic spacer of both species was sequenced. Variation in sequence was lower than expected for different species. Variation in the sequences of tandemly repeated elements was found and may prove useful in distinguishing G. salaris and G. thymalli.

Animals↗
PubMed2004

Prevalence of Heterophyes nocens and Pygydiopsis summa infections among residents of the western and southern coastal islands of the Republic of Korea.

To determine the distribution and prevalence of heterophyid fluke infections on coastal islands of the Republic of Korea, fecal specimens were collected from 4,179 people residing on 45 islands in the West (Yellow) and South Seas and examined using the formalin-ether and Kato-Katz techniques. Eggs of Heterophyes nocens were found in 459 (11.0%) residents of 42 islands, with an average number of eggs per gram (epg) of feces of 79.6. Eggs of Pygidiopsis summa were found in 49 (1.2%) on 12 islands, with an average epg of 253.0. The egg-positive rate for H. nocens was the highest on Chungdo (32.6%), followed by Imchado (27.3%); P. summa was most prevalent on Imchado (15.2%). The majority (78.9% [362 of 549] of those infected with H. nocens and 81.6% [40 of 49] of those infected with P. summa) of those infected were adults more than 40 years old. Adult flukes of these species were recovered from residents of Imchado by treatment with praziquantel and purgation. Our results indicate that H. nocens and P. summa are indigenous to the southern and western coastal islands of the Republic of Korea.

Adolescent↗
PubMed1980

Population biology and host-parasite relationships of Triganodistomum attenuatum (Trematoda: Lissorchiidae) infecting the white sucker, Catostomus commersoni (Lacépède).

Triganodistomum attenuatum demonstrated similar seasonal infection patterns in white suckers, Catostomus commersoni, from the Bellamy and Oyster rivers, New Hampshire. Mean intensity was highest in spring 1975 and 1976. Nongravid and gravid worms were common in the spring, and in the spring and summer, respectively. Most individuals of T. attenuatum parasitized the posterior portion of the sucker's intestine. No definite changes in prevalence and mean intensity were evident at either river as fish size increased. Male and female suckers had similar prevalences and mean intensities of infections. Although a significantly larger number of suckers from the Oyster River was infected than from the Bellamy River, the mean intensities were similar. Triganodistomum attenuatum was found to be host specific to the white sucker. Other fish species examined for the presence of T. attenuatum were as follow: creek chubsucker (Erimyzon oblongus), fallfish (Semotilus corporalis), golden shiner (Notemigonus crysoleucas), bridle shiner (Notropis bifrenatus), common shiner (N. cornutus), longnose dace (Rhinichthys cataractae), redfin pickerel (Esox americanus), pumpkinseed (Lepomis gibbosus), and swamp darter (Etheostoma fusiforme). The state of New Hampshire is a new locality record for T. attenuatum.

Animals↗
PubMed2000

Cercarial productivity of redial generations in single-miracidium infections of Lymnaea truncatula with Paramphistomum daubneyi or Fasciola hepatica.

Single-miracidium infections of Lymnaea truncatula with Paramphistomum daubneyi or with Fasciola hepatica were carried out under laboratory conditions to count free rediae, their germinal embryos, and to determine the cercarial productivity of each redial generation. In snails infected by P. daubneyi, the cercariae were produced by the first (8.7 cercariae per redia) and second (8.9 per redia) generations. At day 63 post-exposure, they corresponded, respectively, to 53.9% and 46.1% of cercariae produced by all rediae. In snails infected by F. hepatica, the majority of cercariae were produced by the R2a group (18.2 cercariae per redia) and corresponded to 66.0% of cercariae produced all rediae. The cercariae produced by the other redial groups were more limited in number: 17.5 per redia in the R1b group (28.7%) and 2.0 per redia in the R2b/R3a group (5.3%). Cercarial productivity of P. daubneyi until day 63 post-exposure was more limited in number than that of F. hepatica: a total of 145 cercariae per snail versus 427 per snail.

Animals↗
PubMed1986

Intestinal absorption studies in Fasciolopsis buski infection.

The intestinal absorption of carbohydrate, fat, protein and vitamin B12, serum vitamin B12, serum and red cell folate levels were performed in 10 patients harbouring F. buski. No disturbance of carbohydrate, fat and protein absorption was observed but vitamin B12 absorption was found to be slightly lower than normal in 8 out of 10 patients, and serum vitamin B12 was also lower than normal in 4 out of 9 patients. Red cell and serum flolate levels were within the normal limits. Histological study of jejunal biopsy was normal in 7 out of 8 patients.

Adolescent↗
PubMed2002

Attachment-inducing capacities of fish skin epithelial extracts on oncomiracidia of Benedenia seriolae (Monogenea: Capsalidae).

Attachment-inducing capacities of skin epithelial extracts of yellowtail, Japanese flounder and red sea bream on oncomiracidia of the monogenean Benedenia seriolae were examined. Clear differences were not detected in the capacity among the fish species, although B. seriolae infects only yellowtail and its congeners in Seriola. This suggests that either the capacity is not host specific or host-specific attachment-inducing capacity cannot be detected by the assay method. Further, the attachment-inducing capacities were suppressed by wheat-germ lectin and concanavalin A in skin epithelial extracts of Japanese flounder and yellowtail, respectively. This suggests that some sugar-related chemical substances existing in fish epithelia induce the attachment of B. seriolae oncomiracidia.

Animals↗
PubMed2000

Spatial distribution and coexistence of monogenean gill parasites inhabiting two damselfishes from Moorea island in French Polynesia.

The ectoparasite fauna of two damselfishes, Stegastes nigricans and Dascyllus aruanus, from Moorea Island in French Polynesia was investigated. Gills of these damselfishes were infected with congeneric Monopisthocotylea Monogenea belonging to the genus Haliotrema. Stegastes nigricans were found to harbour a guild of three Haliotrema species whereas only one species inhabited D. aruanus. Microhabitat distribution, inter- and intraspecific competition and interspecific associations on the gill were studied. Observations on site preference revealed no spatial segregation between the three congeneric species inhabiting the gills of S. nigricans. Juvenile and adult monogeneans of that guild occurred on the same microhabitat. The dominant species Haliotrema sp. 1 did not expand on the microhabitat when the intensity of infection increased. Interspecific association tests revealed positive and negative associations. Haliotrema sp. 4 expanded its distribution on the gills of Dascyllus aruanus when the intensity of infection increased suggesting the likelihood of intraspecific competition. Juvenile and adult monogeneans of Haliotrema sp. 4 appeared to segregate as a result of intraspecific competition. This competition may exist to enhance resource availability when the gill habitat is limited. Overlaps between niche breadth and species microhabitat were revealed for monogenean species inhabiting S. nigricans. Interspecific competition did not appear to play an important role in the distribution of S. nigricans congeneric ectoparasites. Reinforcement of reproductive barriers may have led to the avoidance of hybridization.

Analysis of Variance↗
PubMed2005

Redescription and surface ultrastructure of Pygidiopsis macrostomum (Digenea: Heterophyidae).

Pygidiopsis macrostomum Travassos, 1928, a poorly known species originally described from a single specimen from Rattus norvegicus (Erxleben, 1777) in Brazil, is redescribed on the basis of metacercariae from the mesenteries of naturally infected guppies Poecilia vivipara Bloch and Schneider, 1801 (Poeciliidae), and adults obtained from an experimental infection of hamsters. Pygidiopsis macrostomum is characterized by the absence of oral spines, vitellaria extending forward to ventral sucker, uterus reaching pharyngeal level, X-shaped excretory vesicle, and an oral sucker/acetabulum ratio of 1:0.8. The surface ultrastructure shows that the tegument of the metacercaria does not strongly differ from that of adults. The brush-shaped spines of P. macrostomum are similar to those reported for Pygidiopsis summa and Pygidiopsis ardeae, but no differences in spine shape were observed throughout the body.

Animals↗
PubMedDate not supplied

[Diplostomiasis in fishes in lake farms and the ways for its control].

Diplostomosis is the most common disease affecting Coregonidae in lakes of Karelia where intensive fish farming is conducted. The most acute form of diplostomosis, cercariosis, is especially dangerous for larvae introduced into small water bodies. Depending on a season or weather conditions a shift in the infection rate of fishes with metacercariae takes place. Some ways for diplostomatosis prophylaxis are being suggested. Relatively shallow lakes with low miniralisation of water of sulphate type have been found to be most suitable for Coregonidae nurseries. The very specificity of the intensive use of lakes for fish farming offers possibilities for diplostomosis development. In lakes-nurseries with a regulated water regime the abundance of Lymnaeidae can be reduced by winter draining off the water. The chemical control of mollusks, local use of copper sulphate, is also possible under lake conditions.

Animals↗
PubMed1994

Echinobreviceca coelorhynchae n. gen., n. sp. (Echinobrevicecinae n. subf.), a fellodistomid from Coelorhynchus coelorhynchus (Macrouridae) from the Gulf of Mexico.

During a study of digenean parasites of deep sea fishes from the Gulf of Mexico, 38% (5 of 13) of Coelorhynchus coelorhynchus Risso, 1810, (Macrouridae) were infected with a total of 33 specimens (6.6/infected fish) of an undescribed species of Fellodistomidae representing a new genus and subfamily. Other macrourids collected at the same time (Bathygadus macrops Goode and Bean, 1886, Malacocephalus occidentalis Goode and Bean, 1885, and Nezumia aequalis Günther, 1878) were not infected with Echinobreviceca coelorhynchae n. gen., n. sp. The new species is most similar to members of the subfamily Baccigerinae, but differs in having an I-shaped excretory vesicle, a densely spined tegument, a pretesticular ovary, and a blind seminal receptacle. Echinobrevicecinae n. subf. is separated from other subfamilies in the family by having an I-shaped excretory vesicle. Echinobreviceca n. gen. is established as the type and only genus in the new subfamily, and E. coelorhynchae n. sp. as the only known species in the genus.

Animals↗
PubMed1991

Dactylogyrids on the gills of roach in central Finland: features of infection and species composition.

Monogenean parasites were examined from the gills of 660 roach (Rutilus rutilus) in four interconnected lakes in Central Finland between February and November 1986 and in three of the same lakes between February and December 1988. One of the lakes is eutrophic and polluted due to a paper and pulp mill, one is oligotrophic and in a natural state, and the other two lakes are eutrophic. The prevalence of Dactylogyrus infection was always high. Differences between the lakes and the years were observed in the intensity of infection, which was significantly higher in the polluted lake. The intensity was also higher in older fish. Nine Dactylogyrus species were found, and of these D. crucifer and D. nanus were numerically dominant in all of the lakes studied, especially in the oligotrophic lake. In 1986 D. fallax, D. similis and D. suecicus constituted significant proportions of the fauna in the polluted lake. D. micracanthus was most common in the eutrophic lakes. In 1988 the species composition in the polluted lake was most similar to that in the eutrophic lake.

Animals↗
PubMedDate not supplied

Quantitative hepatobiliary scintigraphy in normal cats and in cats with experimental cholangiohepatitis.

Quantitative hepatobiliary scintigraphy using 99mTc-mebrofenin was performed on eight normal cats and on the same cats after induction of experimental cholangiohepatitis by infection with the liver fluke Platynosomum concinnum. Hepatobiliary scintigraphy was performed 3 times at 10 weeks, 4 months and 6 months after infection. In addition, routine biochemical tests, hepatic ultrasound and ultrasound guided hepatic biopsy samples were obtained at the same time points, and the results compared with hepatobiliary scintigraphy. The normal hepatic extraction fraction was determined to be 85%, and the normal hepatic excretion half time (T 1/2) was 14 minutes. There was no significant change in scintigraphic parameters compared to pre-infection values at any time following infection with the liver fluke. No correlation between scintigraphic parameters and histologic scores was found; however, significant correlation was identified between parasite burden and histologic scores 6 months following infection. Despite the presence of severe multifocal histologic abnormalities, minimal clinical, biochemical and scintigraphic derangements were identified using this model of cholangiohepatitis. Based on this study, hepatobiliary scintigraphy appears to be an insensitive test for structural hepatobiliary abnormalities. The role of hepatobiliary scintigraphy in functional hepatobiliary abnormalities of the feline liver has not been determined.

Aniline Compounds↗
PubMed2000

Observations on the morphology and life-cycle of Procerovum varium (Onji & Nishio, 1916) (Trematoda: Heterophyidae).

The life-cycle of Procerovum varium (Digenea: Haplorchiinae) was studied experimentally and the morphology of stages in the life-cycle has been described and illustrated. Infections with adult flukes were found in the pond heron Ardeola grayii and heavy infections with metacercariae were found, attached to the liver of the fish Oryzias melastigma (Oryziatidae) occurring in a freshwater stream situated in Visakhapatnam, India. The cercariae developing in the snail Thiara tuberculata possessed typical haplorchiine features and were characterised by the presence of numerous cystogenous glands. Early stages of metacercarial development occurred free in the muscles of the fish intermediate host. The larvae reached the liver at 5 days post-infection, encystment commenced 2 days later and 15-day-old metacercariae were found to be infective to chicks, ducks and mice that served as suitable experimental hosts. The adult flukes obtained from natural and experimental infections showed many intraspecific variations, especially in the size and shape of the expulsor which depend on the quantity of sperm it contains. The validity of various species described in the genus and differentiated on the basis of differences in the size of the expulsor has been examined. It is concluded that only three species of the genus, namely P. varium, P. cheni and P. calderoni, are valid. "P. sisonli" of Chen (1949) is confirmed as a synonym of P. varium. P. varium is reported for the first time from India.

Animals↗
PubMed2004

New genus with two new species of capsalid monogeneans from dasyatids in the Gulf of California.

We propose Listrocephalos n. gen. (Monogenea: Capsalidae: Entobdellinae) for 2 new capsalid species that infect the skin of 2 species of diamond stingrays (Dasyatidae) in the Gulf of California. We also provide additional observations on 2 previously described capsalid species, which infect the external body surface of stingrays and are currently in Entobdella Blainville in Lamarck, 1818, and transfer them to the proposed new genus. The members of this genus, Listrocephalos corona (Hargis, 1955) n. comb. (type species), Listrocephalos guberleti (Caballero and Bravo-Hollis, 1962) n. comb., Listrocephalos kearni n. sp., and Listrocephalos whittingtoni n. sp., differ from other entobdellines by the combination of having an anterolateral adhesive pad comprising 2 ventral columns of raised ovoid structures, I pair of glands that flank the preoral depression, a discoid and aseptate haptor that lacks a marginal valve but has clover-shaped papillae dispersed radially over its entire ventral surface, minute and nonoverlapping median haptoral sclerites, a bizarre chamber yielding a duct that opens on the surface of the penis, separate genital pores, and a gland of Goto located between the testes and ovary. Listrocephalos kearni n. sp. infects Dasyatis brevis and is most easily distinguished from its congeners by the combination of lacking penis tubules and having a convoluted proximal portion of the vas deferens that occupies the space between the ootype and ovary. Listrocephalos whittingtoni n. sp. infects Dasyatis longa and is most easily distinguished from its congeners by the combination of having penis tubules and a vaginal pore that is located posterior to the level of the uterus. We report specimens of L. corona from the ventral body surface of Dasyatis say from a new locality, Mississippi Sound, as well as specimens of L. guberleti from the skin of 2 new hosts, Urobatis maculatus and Urobatis concentricus, and a new locality, Elkhorn Slough, California. We provide a diagnostic key and a table of records for Listrocephalos spp.

Animals↗