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PubMed2005

Life cycle of Coitocoecum plagiorchis (Trematoda: Digenea: Opecoelidae).

The life cycle of Coitocoecum plagiorchis Ozaki, 1926 (Coitocaecum is an incorrect subsequent spelling) was studied in the field and laboratory. The study was conducted at the Futatsu River and the Chikugo River, Kyushu, Japan. Adults of C. plagiorchis were obtained from fishes Coreoperca kawamebari, Rhinogobius spp. and Odontobutis obscura. Cotylomicrocercous cercariae with a two-point stylet (=Cercaria distyloides Faust, 1924) were detected in pleurocerid snails (Semisulcospira spp.). Metacercariae with a cyclocoel were obtained from shrimp (Neocaridina denticulata). The cercariae were experimentally exposed to the shrimp, and subsequently metacercariae with a cyclocoel were recovered from the shrimp within 24 days after exposure. These metacercariae were identified as C. plagiorchis. The sporocysts, cercariae, metacercariae and adults are briefly described.

Animals↗
PubMed2005

First report of adult specimens of Sphincterodiplostomum musculosum (Digenea, Diplostomidae).

Sphincterodiplostomum musculosum Dubois, 1936 (Diplostomidae, Diplostominae) was originally described on the basis of specimens collected from the intestine of agami heron, Agamia agami (Gmelin) (Ardeidae), in Mato Grosso, Brazil. The original description of this species was brief because it was based on a few immature specimens. The purpose of this paper is to describe the detailed morphological study of several adult specimens of S. musculosum obtained from the intestine of the great egret, Ardea alba L. (Ardeidae), from Argentina which revealed new characters. This represents a new host record and a new record in birds in Argentina.

Animals↗
PubMed2006

A new species of Acaenodera (Digenea: Acanthocolpidae) parasitizing Conger orbignyanus (Pisces: Congridae) from the coasts of Argentina.

A new species, Acaenodera spinosior, is described based on specimens collected from the intestine of Conger orbignyanus Valenciennes (Pisces: Congridae) caught in waters off Mar del Plata (38 degrees 08'S, 57 degrees 32'W), Argentina. Five of 36 congers examined were parasitized (prevalence: 13.9%, mean intensity: 2.6+/-1.52, range: 1-5). The new species is distinguished from its only congener, Acaenodera placophora Manter and Pritchard, 1960, a parasite of congers off Hawaii, by its larger size, lacking eyespots, and exhibiting a greater number of circumoral, mid-ventral and lateral spines. This is the first record of Acaenodera Manter and Pritchard, 1960 in Atlantic waters.

Animals↗
PubMed2006

Do trematode parasites disrupt defence-cell signalling in their snail hosts?

More than a decade ago, it was postulated that components derived from trematode parasites block receptors on the defence cells of their snail intermediate hosts, thus preventing host-cell activation and parasite elimination. This phenomenon has still not been investigated extensively. However, recent work concerning the molecular regulation of the molluscan defence response provides a new framework for studies that focus on an extension of this original concept - subversion of host cell signalling by trematode parasites. The hypothesis is that, to facilitate survival and replication in their intermediate hosts, trematode parasites down regulate host defence responses by interfering with key signal-transduction pathways in snail defence cells.

Animals↗
PubMed2004

Use of remote sensing and geographical information systems to identify environmental features that influence the distribution of paramphistomosis in sheep from the southern Italian Apennines.

A geographic information system (GIS) was constructed using remote sensing (RS) and landscape feature data together with Calicophoron daubneyi positive survey records from 197 georeferenced ovine farms with animals pasturing in a 3971 km(2) area of the southern Italian Apennines. The objective was to study the spatial distribution of this rumen fluke, identify environmental features that influence its distribution, and develop a preliminary risk assessment model. The GIS for the study area was constructed utilizing the following environmental variables: normalized difference vegetation index (NDVI), land cover, elevation, slope, aspect, and total length of rivers. These variables were then calculated for "buffer zones" consisting of the areas included in a circle of 3 km diameter centered on 197 farms. The environmental data obtained from GIS and RS and from data taken by the veterinarians on the field (stocking rate and presence of streams, springs and brooks on pasture) were analyzed by univariate (Spearman and ANOVA) and multivariate (discriminant) statistical analyses using the farm coprological status (positive/negative) as the dependent variable. Sheep on 32 of the 197 (16.2%) farms, were positive for C. daubneyi, with an average intensity of 52 epg. A multivariate stepwise discriminant analysis model was developed that included moors and heathland, sclerophyllous and coniferous forest vegetation, autumn-winter NDVI and presence of streams, springs and brooks on pasture. The variables entered in the model were also correlated with C. daubneyi positive farms in the univariate tests and are consistent with the environmental requirements of C. daubneyi and its snail intermediate host.

Animals↗
PubMed2005

Wasting and mortality in beef cattle parasitized by Eurytrema coelomaticum in the State of Paraná, southern Brazil.

A sporadic wasting syndrome affecting beef cattle herds parasitized by Eurytrema coelomaticum is described in the State of Paraná, southern Brazil. The disease was characterized by progressive weight loss, poor body condition despite plenty of good quality forage available, and death. Annual losses ranged from 1 to 3%. The clinical course of the disease varied from 2 to 10 months after the onset of the first clinical signs. At necropsy, one of the three distinct following patterns of lesions were observed: the pancreas was of normal size and color; small, shrunken, white and markedly and diffusely firm (fibrosis); or slightly enlarged and dark with a shriveled capsular surface. Myriads of leaf-shaped trematodes of the genus Eurytrema were packed inside multiple dilated ducts with thickened, whitish fibrous walls, or the flukes were embedded in the remaining pancreatic parenchyma. Microscopic findings included extensive loss of the pancreatic parenchyma with replacement fibrosis, intralesional flukes and eggs, and ductal hyperplasia. Inflammatory reaction varied from absent to severe with the presence of a granulomatous reaction around the trematode eggs. One affected animal had high plasma amylase concentration (1580U/L) suggesting exocrine pancreatic insufficiency. Glucose blood levels were not significantly increased. We suggest that diffuse and marked fibrosis of the pancreas induced by the presence of large amounts of pancreatic flukes is the cause of the sporadic cases of chronic wasting and death of cattle in this geographic area.

Animals↗
PubMed2005

Characterization of the second internal transcribed spacer of ribosomal DNA of Calicophoron daubneyi from various hosts and locations in southern Italy.

Isolates of the rumen fluke Calicophoron daubneyi (Digenea: Paramphistomidae) from various hosts and three locations in southern Italy were characterized genetically. The second internal transcribed spacer (ITS-2) of ribosomal DNA (rDNA) plus flanking 5.8S and 28S sequence (ITS-2+) was amplified from individual rumen flukes by PCR. PCR-linked restriction fragment length polymorphism (PCR-RFLP) analysis was performed using four different restriction endonucleases, and PCR products were sequenced. The PCR analyses from all the C. daubneyi specimens produced identical fragments, and the PCR-RFLP analyses did not show, with respect to any of the four restriction endonucleases, any differences between the C. daubneyi specimens. The sequence analyses of the ITS-2+ from each of the C. daubneyi specimens showed them all to be 428 bp, and composed of the entire ITS-2 sequence (282 bp) plus the two partial flanking conserved sequences, 5.8S (99 bp) and 28S (47 bp). No intra-specific variation was observed in the nucleotide composition of the ITS-2+ (homology=100%). There was, however, an observable inter-specific variation between the ITS-2+ of C. daubneyi and the ITS-2+ of both Calicophoron calicophorum (homology=97.2 %) and Calicophoronmicrobothrioides (homology=97.4 %), both previously deposited in the GenBank. The finding of the present study shows that, as has already demonstrated for other parasitic helminths, ITS-2 can serve as an effective genetic marker for the molecular identification of paramphistomes, and as a useful tool for developing molecular epidemiological techniques for the study of C. daubneyi transmission patterns and prevalence in definitive and intermediate hosts.

Animals↗
PubMed1999

Identification of African Paragonimidae by multivariate analysis of the eggs.

A study of metacercariae and adult Paragonimidae revealed the existence in West-Africa of four species, of which two are largely recorded in literature (Paragonimus africanus and Paragonimus uterobilateralis), one was suspected (Paragonimnus westermani-like) and one remained unrecorded in Africa (Euparagonimus sp). Among the two last ones, P. westermani-like was probably confused with P. africanus, and Euparagonimus sp. with P. uterobilateralis. P. westermani-like adult worms differed from P. africanus by the morphology of ovary, testes and the size of the metraterm eggs. Euparagonimus could be identified by a short excretory bladder in metacercariae. The discriminant functions established on eggs measurements (average, maximum and minimum length, average, maximum and minimum width) were able to separate the isolates into four groups. The largest eggs (97 x 59 microm) belonged to P. westermani-like, the medium sized eggs were ascribed to P. africanus (91 x 49 microm) and to Euparagonimus sp. (84 x 50 microm), and the smaller eggs (69 x 42 microm) were identified as P. uterobilateralis. Three Paragonimidae were identified in Cameroon: P. westermani-like, P. africanus and Euparagonimus sp. Additionally, P. uterobilateralis, P. westermani-like, and Euparagonimus sp. were found in the Congo, Gabon, and the Ivory Coast, respectively.

Africa, Western↗
PubMed2002

Detection of bird schistosomes in lakes by PCR and filter-hybridization.

Many lakes around the world are contaminated with bird schistosome cercariae, which penetrate into human skin, causing an itching dermatitis called "swimmers' itch." Bathers could be forewarned from exposure to the larvae and ecological examinations could be performed, when a sensitive method to detect the parasites in aquatic systems, where lots of organisms hinder microscopic examinations, would be available. For this purpose we cloned, sequenced, and analyzed a 396 bp tandem repeated DNA sequence from Trichobilharzia ocellata (ToSau3A), and employed it for developing molecular detection assays. It hybridized with less than 100 pg DNA from different Trichobilharzia species (T. ocellata, Trichobilharzia franki, and Trichobilharzia regenti), but not with 10 ng DNA from other related or sympatric trematodes. A PCR assay, amplifying this sequence with the same specificity, detected 100 fg T. ocellata DNA, 1 cercaria in 0.5 g plankton, and 2 cercariae in 0.5 g host snail tissues.

Animals↗
PubMed2000

Nestedness in assemblages of gyrodactylids (Monogenea: Gyrodactylidea) parasitising two species of cyprinid--with reference to generalists and specialists.

The structure of gyrodactylid assemblages in individual fishes of two species of cyprinid was determined. A total of 100 specimens of minnow, Phoxinus phoxinus, and 137 specimens of roach, Rutilus rutilus, were investigated for presence of gyrodactylids. Host specificity, specialists vs. generalists, was noted in each host fish. A nested pattern was recorded in parasite assemblages of minnow, the host with a dominant number of specialist gyrodactylids. A non-nested pattern was observed in parasite assemblages of roach, the host with a dominant number of generalist gyrodactylids. The host specificity appears to be a meaningful factor that determines the pattern of gyrodactylid assemblages of both fish hosts.

Animals↗
PubMed2000

Co-existence of nine gill ectoparasites (Dactylogyrus: monogenea) parasitising the roach (Rutilus rutilus l.): history and present ecology.

Co-existence among potentially competing species can be favoured by niche specialisation and/or by reducing the overall intensity of competition via aggregated utilisation of fragmented resources. We investigated the respective roles of niche specialisation and aggregation in the case of nine congeneric monogenean parasites on the gills of Roach (Rutilus rutilus L.) belonging to the genus Dactylogyrus. The position of each individual parasite of the nine Dactylogyrus species was recorded. Niche breadth and niche overlap of parasite species were estimated. Comparative methods, which take into account phylogenetic information of the analysed species, were used. We reconstructed a phylogeny of the nine Dactylogyrus species based on morphological characters. We used the 'aggregation model of co-existence' in the model to test if species co-existence is facilitated when intraspecific aggregation exceeds interspecific aggregation. We observed a lack of negative correlation in abundance between pairs of parasites, and a negative correlation between niche size and parasite aggregation, for both intraspecific and interspecific aggregation. Our comparative analysis showed that parasite abundance is positively correlated with niche breadth. Then parasite abundance, and not interactions between Dactylogyrus species, seems to be the most important factor determining niche size This result gives some support to niche segregation by specialisation. Niche size was negatively correlated with both intraspecific and interspecific aggregation. No relationship was found between an increase of interspecific aggregation with an increase of niche overlapping, which suggests that competition may play little role. A lack of competition could be also confirmed by the lack of negative correlation in abundance between species pairs. A parsimony analysis of the evolution of gill distribution indicates a change in one parameter of the niche (arch, segment and/or area) at each branching event.

Animals↗
PubMed2001

The phylogenetic position of Furnestinia echeneis (Monogenea, Diplectanidae) based on molecular data: a case of morphological adaptation?

The genus Furnestinia (Diplectanidae) contains only one species, Furnestinia echeneis. However, its close morphological similarity with the genus Lamellodiscus (Diplectanidae) raises doubt concerning its placement in a separate genus. These two genera differ only by their number of lamellodiscs: one for Furnestinia, two for Lamellodiscus. Here, the taxonomic position of F. echeneis is investigated via a phylogenetic reconstruction based on partial 18S rDNA for F. echeneis and several Lamellodiscus species. Furnestinia echeneis appears to be clearly nested into the Lamellodiscus genus, these two genera should then be synonymised. The hypertrophy of its unique lamellodisc is hypothesised to be a morphological adaptation for attachment to the host.

Adaptation, Physiological↗
PubMed2001

A molecular phylogeny of the genus Ichthyocotylurus (Digenea, Strigeidae).

Three nucleotide data sets, two nuclear (ribosomal internal transcribed spacer regions 1 and 2, ITS1 and ITS2) and one mitochondrial (cytochrome c oxidase subunit 1, CO1), were analysed using distance matrix and maximum likelihood methods to determine the inter-relationships amongst the four species attributed to the genus Ichthyocotylurus Odening, 1969. Sequence data obtained from all gene loci investigated supported the position of Ichthyocotylurus variegatus as a species discrete from Ichthyocotylurus platycephalus. Phylogenetic analyses yielded congruent trees, with I. variegatus isolates comprising a common clade to which I. platycephalus constitutes a sister taxon. Ichthyocotylurus erraticus and Ichthyocotylurus pileatus were found to demonstrate a similarly close inter-specific relationship. The greatest intra-generic divergence occurred in the CO1 region (16% variability), with resultant disparities in three to eight encoded amino acids. PCR amplification yielded multiple ITS1 products for all Ichthyocotylurus spp. Analyses of equivalent-sized amplicons showed 5.4% intra-generic variation and several point mutations between I. variegatus isolates from different geographical localities and from different piscine hosts. The ITS2 locus was extremely conserved, with less than 1% variation between species. No intra-specific variation was recorded for any CO1 or ITS2 sequences.

Animals↗
PubMed2001

Order and disorder in ectoparasite communities: the case of congeneric gill monogeneans (Dactylogyrus spp.).

The measure of order and disorder in the distribution of species in fragmented habitats proposed by Atmar and Patterson (Oecologia, 96 (1993) 373-82) was applied to investigate nested patterns of Dactylogyrus species parasitising the gills of roach. Organisation in dactylogyrid assemblages was investigated at three levels: (1) host populations between localities; (2) local host populations over seasons; and (3) individual hosts over one season within a local host population. Dactylogyrid assemblages showed nested patterns when analyses were conducted at the level of localities (among host populations) and at the level of seasons (among host populations within localities). The analysis at the level of hosts (infracommunities of parasites) revealed that nested pattern is not common. We suggest that nestedness may have a variety of causes and does not necessarily imply competition.

Animals↗
PubMed2002

Entobdella soleae--pointers to the future.

The biology of the monogenean skin parasite Entobdella soleae and its relationship with its host, the common sole (Solea solea), are probably better known than those of any other monogeneans. The author describes his early involvement with this parasite and the special features of parasite and host that make this relationship so suitable for parasitological studies. Aspects of the biology of E. soleae that have been investigated are briefly mentioned, but most of the paper is concerned with areas of the parasite's biology that remain a challenge to determine. Unresolved areas are as follows: (1) the identity of the factor (or factors) in host skin mucus that stimulates hatching of the parasite's eggs; (2) whether or not the larvae of the parasite are attracted to their host; (3) the nature of factors controlling the contrasting behaviour of adult parasites on the upper and lower surfaces of the host; (4) how nutrients are supplied to the remote regions of the haptor; (5) whether the host has any control via its immune system over parasite invasion success and survival; (6) how the parasite copes with the migratory habits of some sole populations, assuming that such populations are infested with the parasite. The intimacy of this parasite/host relationship is its most remarkable feature, the reflection of which, not surprisingly, is the greatly restricted host range of the parasite. E. soleae has been reported from only three host species, all highly specialised bottom-dwelling members of Solea. It is all the more surprising that relatives of E. soleae, such as Neobenedenia melleni, retain the ability to parasitise an enormous range of hosts. How this versatility is achieved remains to be seen.

Animals↗