Search results for "trematoda"

Kuhan (Sander lucioperca) soveltuvuus kolmen imumatoloislajin väli-isännäksi: alttius infektiolle ja loisten vaikutus kalan käyttäytymiseen

2008

Specific tyrosine phosphorylation in response to bile in Fasciola hepatica and Echinostoma friedi

2003

Protein tyrosine phosphorylation (PY) is a well-known signalling mechanism which is also involved in host-parasite interactions. Despite its transcendence, PY has been poorly studied in parasitic helminths. The aim of this study is to examine the effect of bile salts on the PY pattern in parasitic trematodes. Two distinct adult models were analysed: Echinostoma friedi, of intestinal habitat, and Fasciola hepatica, naturally inhabitant of host biliary channels. Our results show that bile salts induce specific and distinct protein PY in both trematode species, indicating that this signalling process seems to be also involved in host-trematode relationships.

The revised microRNA complement of Fasciola hepatica reveals a plethora of overlooked microRNAs and evidence for enrichment of immuno-regulatory micr…

2015

MicroRNAs (miRNAs) are gene regulators that have recently been shown to down-regulate the immune response via extracellular vesicles in the mammalian host of helminthic parasites. Using the miRNA prediction pipeline miRCandRef, we expanded the current miRNA set of the liver fluke Fasciola hepatica (Platyhelminthes, Trematoda) from 16 to 54 miRNAs (42 conserved and 13 novel). Comparing the cellular expression levels with extracellular vesicles, we found all miRNAs expressed and enriched for miRNAs with immuno-regulatory function, tissue growth and cancer. Our findings support the hypothesis that miRNAs are the molecular mediators of the previously demonstrated immune modulatory function of e…

Grouping facilitates avoidance of parasites by fish

2013

Background. Parasite distribution is often highly heterogeneous, and intensity of infection depends, among other things, on how well hosts can avoid areas with a high concentration of parasites. We studied the role of fish behaviour in avoiding microhabitats with a high infection risk using Oncorhynchus mykiss and cercariae of Diplostomum pseudospathaceum as a model. Spatial distribution of parasites in experimental tanks was highly heterogeneous. We hypothesized that fish in groups are better at recognizing a parasitized area and avoiding it than solitary fish. Methods. Number of fish, either solitary or in groups of 5, was recorded in different compartments of a shuttle tank where fish co…

Survival and infectivity of Hypoderaeum conoideum and Euparyphium albuferensis cercariae under laboratory conditions.

1999

The survival characteristics of the cercariae of Hypoderaeumconoideum and Euparyphiumalbuferensis (Trematoda: Echinostomatidae) at 20°C and 30°C are described, and the age dependency of their infectivity at 20°C is studied to determine their respective transmission efficiencies. Cercarial survival was found to be age-dependent and was higher at 20°C. For both cercariae, the maximum life-span was 26 h at 20°C and 16 h at 30°C, and their respective times to 50% mortality were similar at each temperature. Both cercariae seem to be well adapted to transmission in their natural habitat, though cercarial infectivity of H. conoideum was higher than that of E. albuferensis, this being correlated wi…

Interactions among co-infecting parasite species: a mechanism maintaining genetic variation in parasites?

2008

Individuals of free-living organisms are often infected simultaneously by a community of parasites. If the co-infecting parasites interact, then this can add significantly to the diversity of host genotype×parasite genotype interactions. However, interactions between parasite species are usually not examined considering potential variation in interactions between different strain combinations of co-infecting parasites. Here, we examined the importance of interactions between strains of fish eye flukes Diplostomum spathaceum and Diplostomum gasterostei on their infectivity in naive fish hosts. We assessed the infection success of strains of both species in single-strain exposures and in co-…

Echinostoma friedi: the effect of age of adult worms on the infectivity of miracidia.

2004

AbstractThe effect of ageing of adults ofEchinostoma friedi(Trematoda: Echinostomatidae) on the infectivity of miracidia yielded was analysed. Miracidia were obtained after hatching of eggs obtained from adult worms ofE. friedicollected weekly during the course of experimental infections in golden hamsters. Miracidial infectivity, measured in terms of percentage of infection inLymnaea peregra, was significantly influenced by the age of the adult worms from which the miracidia were derived. Infective miracidia only were obtained from adult worms in the age range from 4 to 9 weeks post-infection. Infectivity was maximal in those miracidia derived from adults collected 8 and 9 weeks post-infec…

Manipulation of fish host by eye flukes in relation to cataract formation and parasite infectivity

2005

Trophically transmitted parasites may predispose infected hosts to predation by altering host behaviour, which can be either an adaptation of the parasites to enhance transmission to the next hosts in the life cycle or a nonadaptive side-effect of infection. In an experimental study, we investigated host manipulation by Diplostomum spathaceum (Trematoda), an eye fluke of fish, to evaluate its adaptive value as a parasite strategy to increase transmission efficiency to bird hosts. The parasite induces cataract formation in the lenses of fish eyes, and predisposes fish to predation by reducing their escape response. We examined the effect of developmental stage and the number of parasites on …

The first community-based report on the effect of genital Schistosoma haematobium infection on female fertility.

2009

A cross-sectional study in an Schistosoma haematobium endemic area of rural Zimbabwe examined 483 resident women between the ages of 20 and 49 years who were interviewed about fertility. S. haematobium ova in genital tissue was found to be significantly associated with infertility.

Intestinal Trematode Infections

2014

Intestinal trematodes are among the most common types of parasitic worms. About 76 species belonging to 14 families have been recorded infecting humans. Infection commonly occurs when humans eat raw or undercooked foods that contain the infective metacercariae. These parasites are diverse in regard to their morphology, geographical distribution and life cycle, which make it difficult to study the parasitic diseases that they cause. Many of these intestinal trematodes have been considered as endemic parasites in the past. However, the geographical limits and the population at risk are currently expanding and changing in relation to factors such as growing international markets, improved tran…