Academic literature on the topic 'Microphallidae'

AbstractMicrophallid trematodes are common parasites in marine snails and crustacean hosts at Kuwait Bay. The larval stages of two microphallids,Maritrema eroliaeandProbolocoryphe uca, are difficult to differentiate morphologically. In this study, two PCR-based techniques were established for quick and accurate discrimination between the larval stages of the two microphallid species, employing restriction fragment length polymorphism (PCR-RFLP) and species-specific primers. Both techniques utilized nucleotide differences in the second internal transcribed region (ITS2) of the ribosomal DNA (rDNA) in the two species. For the PCR-RFLP technique, restriction enzymeAvaII was selected and it generated different restriction profiles among the two microphallids. In addition, species-specific primers were prepared for each microphallid species that amplified distinctive fragments. Both techniques showed that the larval stages of the two microphallid species can be identified accurately. However, direct PCR amplification using species-specific primers was more advantageous than the PCR-RFLP technique since it allowed rapid and specific discrimination between the two species. This technique provides a useful tool that can be used in future studies for the study of the distribution of microphallid species and their definitive hosts at different localities of Kuwait Bay.

AbstractThe cyst wall of the metacercaria of Gynaecotyla adunca (Microphallidae: Digenea) was subjected to comprehensive histochemical analysis. At the light microscope level, a uniformly thick, bipartite cyst wall, probably wholly of parasite origin, was evident. Structural modification of the cyst wall to provide an escape aperture was not apparent. The thicker, inner layer was comprised of phospholipid and glyco- and/or mucoproteins, possibly similar in structure to collagen. The outer layer was highly proteinaceous and contained additional amounts of acidic and neutral mucosubstances. The results are discussed in the context of previous observations regarding the excystment requirements of this microphallid species.

The adult worms of the Microphallidae family are mainly found as intestinal parasites of birds and mammals, while metacercariae is most commonly found in decapodal crustaceans. The Microphallidaeare family is spread throughout the world. It includes approximately 47 genera. Mature worms usually enter the digestive system of vertebrates, especially birds and mammals. Microphallidae contain eight subfamilies: Androcotylinae - Basantisiinae - Endocotylinae - Gynaecotylinae - Levinseniellinae - MaritrematinaeMicrophallinae - Sphairiotrematinae. Therefore, due to the lack of studies on the Microphallidae family in Iraq, we began to develop a database on this important family.

AbstractThe prosobranch gastropod Cerithidea cingulata (Gastropoda: Potamididae) in Kuwait Bay was examined for larval trematode infections over a 17-month period. A total of 2537 snails were examined and 1265 (49.9%) found to be infected with one or more species of trematodes. The component community in the snail comprised 12 species representing the families Cyathocotylidae (2), Echinostomatidae (2), Haplosplanchnidae (1), Heterophyidae (2), Microphallidae (1), Philophthalmidae (2), Plagiorchiidae (1) and Schistosomatidae (1). Cyathocotylid II (41.6%) was by far the most prevalent species followed by the microphallid (3.9%), the two species comprised 90% of the total trematode fauna. The prevalence of infection increased with shell size and was significantly higher in male (47%) than female (33%) snails. Multiple infections were observed in only 15 (1.2%) of the infected snails; cyathocotylid I and cyathocotylid II combination occurred 14 times and heterophyid I and the microphallid occurred once. Trematode species were more diverse and prevalent in winter, and cercarial shedding peaked in summer. Behaviour of the definitive host and snail population dynamics were probably the major contributors to the detected temporal pattern in the infections.

AbstractDuring a survey of edible Crustacea for recovery of infective stages (metacercariae) of potential helminthozoonoses of trematode origin in north-east India, the crab species Barytelphusa lugubris mansoniana, collected from suspected foci of lungfluke infection in Meghalaya and Assam, was found to harbour metacercarial cysts that were different from the earlier reported infection, in which the lungfluke Paragonimus was confirmed to be implicated. Using morphological criteria, this metacercaria was identified as Microphallus indicus Mukherjee & Ghosh, 1967 of the trematode family Microphallidae. The present study extends the previous work by providing molecular characterization of this parasite using ribosomal internal transcribed spacer regions (rDNA ITS1 and ITS2) and the partial large ribosomal subunit DNA, lsr. These target regions were amplified by polymerase chain reaction (PCR) using trematode universal primers and sequenced. In BLAST analysis the query sequences were found close to members of Microphallidae and closest to the genus Microphallus.

Most, if not all, animals will at some stage in their lives encounter parasites. Some of the most widespread and abundant parasites belong to the Class Trematoda. Trematodes often have a substantial negative impact on individual intermediate host ecology. In this thesis, I investigate ecological and evolutionary consequences of the interaction between the microphallid trematode, Maritrema novaezealandensis, and its intermediate snail and crustacean hosts. Parasites often show a heterogeneous spatial distribution pattern in natural animal host populations. In this study, factors determining the spatial distribution of larval trematodes in Zeacumantus subcarinatus were investigated at two spatial scales (within and among bays). The distribution of shorebird definitive hosts explained a significant amount of the variation in the distribution of trematodes among bays. However, within a bay, other factors override the effect of bird distribution. The influence of larval trematodes on reproduction, survival and population density of Z. subcarinatus was investigated using laboratory and field studies. In the laboratory, it was found that larval trematodes induce castration and mortality of Z. subcarinatus. The field study revealed that the local prevalence of trematodes had a significant negative effect on population density of Z. subcarinatus. Through castration, trematodes act as strong selective agents on snail host life history. The effect of trematodes on life history characteristics (reproductive effort, juvenile growth, size at maturity and susceptibility to trematode infections) were investigated among natural populations of Z subcarinatus. Reproductive effort was not higher for uninfected females from populations where the risk of becoming infected was high. However, offspring from those populations were significantly larger, and laboratory-reared juveniles grew significantly faster than conspecifics from other populations. In addition, size at maturity was negatively correlated with trematode prevalence across snail populations. Z. subcarinatus thus adapts to a high local risk of trematode infection by reaching maturity early, thereby increasing the chance of reproducing. The influence of M. novaezealandensis on the survial of the amphipod host, Paracalliope novizealandiae was examined using experimental infections and field observations. The experimental infections demonstrated that parasite-induced mortality was intensity-dependent. The number of M. novaezealandensis per amphipod was too low to significantly induce host mortality in the field. However, the transmission strategy of this parasite allows it to affect host populations during weather conditions ideal for trematode transmission. Trematode strategies in the second intermediate host are important to the understanding of host-parasite co-evolution and the evolution of parasite life cycles. In this study, potential density-dependent effects at the metacercarial stage on size and fecundity of in vitro adult M. novaezealandensis was examined in both experimentally infected P. novizealandiae and naturally infected Macrophthalmus hirtipes. For this purpose, a method to excyst and cultivate M. novaezealandensis metacercariae to an egg producing stage, was developed. Naturally infected M. hirtipes also harboured larval stages of three other helminths. Crowding effects in the two crustacean hosts were expressed as a decreased volume and smaller egg production of in vitro adult M. novaezealandensis. In addition, interspecific interactions among parasite species were observed in crab hosts. The work in this thesis provides evidence that M. novaezealandensis significantly and negatively affect intermediate host ecology. The heterogeneous distribution of trematodes causes differential effects among host populations with subsequent effects on the life history of snail hosts. In addition, this study demonstrates that parasites interact within their second intermediate host with possible implications for the way parasites exploit their hosts.

"The biodiversity and ecology of marine cercariae in Australia is poorly known. Although nassariid gastropods are widely distributed in Australia and are expected to have a diverse parasite fauna similar to that of other nassariids worldwide, their cercariae have not been characterised. Nassarius dorsatus, N. olivaceus and N. pullus were collected at three separate estuarine localities in central Queensland between August 2004 and August 2006 and their emergent cercariae characterised using morphological and molecular methods. Fifteen morphotypes of cercariae from six families that infect fishes and birds as definitive hosts were characterised. The highest richness was within the Acanthocolpidae (nine morphotypes) which comprised three cercariae interpreted as species of Stephanostomum and a complex of six unusual cercariae with a ventral keel. Molecular characterisation of these six cercariae supported their placement in the Acanthocolpidae and indicated that they comprised only three species, two of which displayed marked phenotypic plasticity. Molecular analysis supported the characterisation of the three species of Stephanostomum and suggested that one of the unusual cercariae was a species of Stephanostomoides. Dissection of fish from Sandy Point provided a single match; the sequence for a metacercaria in Valamugil buchanani, the blue-tail mullet, was identical to that of one of the species of Stephanostomum. There were two cercariae from the Echinostomatidae and one from each of the Lepocreadiidae, Microphallidae, Opecoelidae and Zoogonidae. Molecular analyses supported the placement of the cercariae from the Echinostomatidae, Lepocreadiidae, Opecoelidae and Zoogonidae within their respective families. The cercaria from the Lepocreadiidae was identified by comparison to known adult data and putatively corresponds to Prodistomum keyam, a parasite of Monodactylus argenteus, the silver moony or butter bream, common in the study region. Morphological analysis supported the characterisation of both of the Echinostomatidae as species of Himasthla. Although no other cercariae could be characterised to genus level, the opecoelid cercaria was determined to be in the subfamily Opecoelinae. Nassarius olivaceus was infected by three acanthocolpid cercariae and one cercaria from each of the other families. Nassarius dorsatus was infected by five acanthocolpid cercariae and one each from the Echinostomatidae and Lepocreadiidae. Nassarius pullus was infected by a single cercaria from the Echinostomatidae. Most cercariae were specific to a single species of gastropod; only four infected two species and none infected all three. Cercariae that infect fish as a definitive host were found at all three localities; but cercariae that infect birds were restricted to a single locality, Sandy Point at Corio Bay, important for domestic and migratory bird species. These results emphasise the relative significance of Sandy Point as an important bird habitat. In total, 126 infections were diagnosed (115 by cercarial emergence), with both the highest frequency of infection and number of infections in N. olivaceus (frequency 5.3%; n=102; 81% of infections), followed by N. dorsatus (1.1%; 20; 16%) and N. pullus (0.2%; 4; 3%). The highest number of infections occurred at Sandy Point (66; 52% of infections), followed by Cawarral Creek (38; 30%) and then Ross Creek (22; 17%). The highest number of infections was by the Acanthocolpidae (54; 43%). Diagnosis of infection by emergence was suitable for all cercariae except the opecoelid, which was underdiagnosed. Nassarius olivaceus had the longest survival in captivity (~4.5 y), followed by N. dorsatus (~0.8 y) and N. pullus (~0.3 y). Almost all infections remained patent for the life of the gastropod. Families commonly found in nassariids worldwide include Acanthocolpidae, Echinostomatidae, Lepocreadiidae and Zoogonidae. Nassariid gastropods are also the dominant marine first intermediate hosts for the Acanthocolpidae, Lepocreadiidae and Zoogonidae and one of the three most common first intermediate host families for species of marine Himasthla. Molecular relationships also indicate that the Acanthocolpidae and Brachycladiidae may actually be comprised of three discrete groups, the Stephanostomum + Monostephanostomum group, the Brachycladiidae, and a group of non-Stephanostomum species comprising Pleorchis, Tormopsolus and Stephanostomoides. This research adds information about the parasite assemblages of nassariid gastropods in Australia, adding 12 new cercarial species and 16 new host-parasite records. Cercarial reports for the Acanthocolpidae, Echinostomatidae, Lepocreadiidae, Opecoelidae and Zoogonidae have been comprehensively reviewed and patterns of association between nassariids and their common parasite families presented. As well, this research has provided a potential avenue for a review of the Acanthocolpidae, a family which is currently considered a ‘catch-all’ group."