Intestinal Trematode Infections

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…

Presence of potentially pathogenic free-living amoebae strains from well water samples in Guinea-Bissau

Free-living amoebae (FLA) include opportunistic pathogens such as Naegleria fowleri, Balamuthia mandrillaris, and the genera Sappinia and Acanthamoeba. In this study, a survey was conducted in order to evaluate the presence of potentially pathogenic amoebic strains in water samples collected from wells located in the western part of Guinea-Bissau. The samples were left to precipitate for 48 hours and then the sediments were seeded on non-nutrient agar plates containing Escherichia coli spread and cultures were checked daily for the presence of FLA. Identification of FLA strains was based on the morphological and polymerase chain reaction (PCR) using the 18S rDNA or 16S mitochondrial rDNA ge…

Echinostoma caproni: Differential tegumental responses to growth in compatible and less compatible hosts

Abstract The topography of the tegument of Echinostoma caproni adults collected from high (mice) and low (rats) compatible hosts was compared by SEM. In the oral (OS) and the ventral sucker (VS) areas, a worm age–host species interaction was found with regard to the density of spines. There was a decrease in the density of spines in the adults collected from mice, whereas an increase occurred in the OS area in worms from rats over time. The tegumentary spines in adults from mice became larger and blunter. Some spines from the VS area in adults from mice at 4 wpi were multipointed. The spines of adults from rats were sharper, not covered by the tegument and no multipointed spines were observ…

Additional file 1 of Interleukin-25-mediated resistance against intestinal trematodes does not depend on the generation of Th2 responses

Additional file 1: Table S1. Applied Biosystems Inventoried assays used in the present work.

Definitive host influences the proteomic profile of excretory/secretory products of the trematode Echinostoma caproni

Background Echinostoma caproni is an intestinal trematode extensively used as experimental model for the study of factors that determine the course of intestinal helminth infections, since this markedly depends on the host species. Although the host-dependent mechanisms for either chronic establishment or early parasite rejection have been broadly studied, little is known regarding the parasite response against different host environments. Methods To identify host-dependent differentially expressed proteins, a comparative proteomic analysis of the excretory/secretory products released from E. caproni adults, isolated from hosts displaying different compatibility with this trematode, was per…

A QUANTITATIVE APPROACH TO THE EXPERIMENTAL TRANSMISSION SUCCESS OF ECHINOSTOMA FRIEDI (TREMATODA: ECHINOSTOMATIDAE) IN RATS

Using a range of parameters, the ability of rats (Rattus norvegicus) to successfully transmit Echinostoma friedi to the next host was examined under experimental conditions. The concept of Experimental Transmission Success (TM), defined as the number of hosts that become successfully infected after exposure to a number of infective stages produced by a previous host per unit of inoculation at which this latter host was exposed, was introduced. Using data for the egg output and miracidium hatching and infectivity, the TM permits us to estimate the ability of a particular defintive host species to successfully transmit a parasite species. This concept may be also useful to compare the transmi…

Echinostoma caproni: intestinal pathology in the golden hamster, a highly compatible host, and the Wistar rat, a less compatible host.

The histopathological changes induced by Echinostoma caproni (Trematoda: Echinostomatidae) in a high (golden hamster) and a low compatible host (rat) were compared at 15 and 30 days post-infection. Infection of rats was characterized by a progressive increase in erosion of villi and elevated numbers of goblet cells, which could be related to the early expulsion of the parasite in a host of low compatibility. In contrast to rats, the number of goblet cell in E. caproni-infected hamsters was low, but increased numbers of neutrophils and mesenteric inflammatory cells were observed. This indicated that local inflammatory responses in hamsters were greater than in rats. An immunohistochemical st…

Th2 and Th1 Responses: Clear and Hidden Sides of Immunity Against Intestinal Helminths.

Intestinal helminthiases affect millions of people worldwide, mainly in developing regions, where they cause a significant negative impact on human health and socioeconomic growth of affected populations. However, intestinal helminthiases are still among the most neglected tropical diseases. Protective immunity against intestinal helminths is associated with development of type 2 responses. Nevertheless, in some host–intestinal helminth combinations, local Th1 responses are initiated, inducing chronicity. The usage of helminth–mouse models is useful for elucidating the mechanisms behind the initiation of each type of response. Herein, the current knowledge on these topics is reviewed, payin…

Kinetics of echinostoma caproni (trematoda: echinostomatidae) antigens in feces and serum of experimentally infected hamsters and rats

This study reports on the kinetics of antibody production to Echinostoma caproni and the dynamics of antigens in feces and sera in 2 experimental hosts (hamsters and rats) that display different degrees of susceptibility with this echinostome. Echinostoma caproniproduced chronic infections in hamsters, whereas rats lost the infection at 49-56 days postinfection (DPI). Hamsters developed higher antibody responses than rats, probably in relation to different intestinal absorptions of worm antigens in each host species. The levels of coproantigens were indicative of the course of infection in each host. Positive coproantigen levels were detected at 1-2 DPI in both hosts, and the values remaine…

Differential alterations in the small intestine epithelial cell turnover during acute and chronic infection with Echinostoma caproni (Trematoda)

Background The intestinal epithelium plays a multifactorial role in mucosal defense. In this sense, augmented epithelial cell turnover appears as a potential effector mechanism for the rejection of intestinal-dwelling helminths. Methods A BrdU pulse-chase experiment was conducted to investigate the infection-induced alterations on epithelial cell kinetics in hosts of high (mouse) and low (rat) compatibility with the intestinal trematode Echinostoma caproni. Results High levels of crypt-cell proliferation and tissue hyperplasia were observed in the ileum of infected mice, coinciding with the establishment of chronic infections. In contrast, the cell migration rate was about two times higher …

Echinostoma caproni (Trematoda): differential in vivo cytokine responses in high and low compatible hosts.

In order to investigate the factors determining the expulsion of intestinal trematodes, we have analyzed the in vivo cytokine responses at several levels and the local responses against Echinostoma caproni (Trematoda) in two host species displaying different compatibility with the parasite. The response of the high compatible host (mice) is characterized by a mixed Th1/Th2 phenotype in the spleen, Peyer's patches and mesenteric lymph nodes. At the intestine, a marked Th1 response with a marked increase of IFN-γ together with elevated number of mucosal neutrophils and expression of induced nitric oxide synthase were observed. The responses in the host of low compatibility (rats) with the par…

Diagnosis of Human Trematode Infections

Digenetic trematodes form a major group of human parasites, affecting a large number of humans, especially in endemic foci. Over 100 species have been reported infecting humans, including blood, lung, liver, and intestinal parasites. Traditionally, trematode infections have been diagnosed by parasitological methods based on the detection and the identification of eggs in different clinical samples. However, this is complicated due to the morphological similarity between eggs of different trematode species and other factors such as lack of sensitivity or ectopic locations of the parasites. Moreover, the problem is currently aggravated by migratory flows, international travel, international t…

The transcriptome of Echinostoma caproni adults: further characterization of the secretome and identification of new potential drug targets.

Abstract Echinostomes are cosmopolitan parasites that infect a large number of different warm-blooded hosts, both in nature and in the laboratory. They also constitute an important group of food-borne trematodes of public health importance mainly in Southeast Asia and the Far East. In addition, echinostomes are an ideal model to study several aspects of intestinal helminth biology, since they present a number of advantages. For example, echinostomes are large worms whose life cycle is relatively easy to maintain in the laboratory. Recently, several studies documented their great value in the study of intestinal helminth–vertebrate host relationship. Detailed knowledge of their genome, trans…

New Insights into the Treatment of Foodborne Trematode Infections

High fascioliasis infection in children linked to a man-made irrigation zone in Peru.

We detected 10 protozoan and nine helminth species in surveys of 338 5-15 year-old Quechua schoolchildren in three communities of the Asillo zone of the Puno region, located at a very high altitude of 3910 m in the Peruvian Altiplano. The area proved to be hyperendemic for human fascioliasis with a 24.3% overall mean prevalence of Fasciola hepatica, local prevalences ranging between 18.8 and 31.3%, and infection intensities of up to 2496 eggs per gram of faeces (epg), with 196-350 epg (mean: 279 epg) and 96-152 epg (123 epg) as arithmetic and geometric means, respectively. Prevalences did not significantly vary between schools and in relation to sex. No statistical differences were found in…

Immunological Characterization of Somatic and Excretory–Secretory Antigens of Echinostoma caproni (Trematoda: Echinostomatidae) in Experimentally Infected Rats

The antigenic properties of somatic (SoP) and excretory-secretory products (ESP) of Echinostoma caproni were studied in experimentally infected rats. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis demonstrated a total of 15 and 9 major polypeptides, in the molecular weight range 10-165 kDa, in SoP and ESP products, respectively. Further analysis revealed some common as well as several unique polypeptides for each type of extract. A total of 2 polypeptides, weighing 58 and 115 kDa, were found in both types of antigen. Indirect enzyme-linked immunosorbent assay analysis using both types of antigens showed that rats developed a weak and slow response in infections with E. caproni. …

Interleukin-25-mediated resistance against intestinal trematodes does not depend on the generation of Th2 responses

AbstractInterleukin-25 (IL-25) is recognized as the most relevant initiator of protective Th2 responses in intestinal helminth infections. It is well known that IL-25 induces resistance against several species of intestinal helminths, including the trematode Echinostoma caproni. E. caproni has been extensively used as an experimental model to study the factors determining the resistance to intestinal infections. Herein, we assessed the role of IL-25 in the generation of resistance in mice to E. caproni infections. ICR mice are permissive hosts for E. caproni in which chronic infections are developed in relation to the lack of IL-25 production in response to primary infection and the consequ…

Echinostoma caproni: kinetics of IgM, IgA and IgG subclasses in the serum and intestine of experimentally infected rats and mice.

The kinetics of specific immunoglobulin M, A and IgG subclasses against Echinostoma caproni (Trematoda: Echinostomatidae) were analyzed in serum and intestinal fluid of two host species (Wistar rats and ICR mice) in which the course of the infection markedly differs. In rats, the worms were rapidly expelled, whereas E. caproni evokes in mice long-lasting infection. The pattern of antibody responses in both serum and intestinal samples was different in each host species. Serum responses in mice were characterized by significant increases of IgM, IgA, total IgG, IgG1 and IgG3, but not IgG2a. In contrast, serum responses in rats showed elevated levels of IgM, probably in relation to thymus-ind…

Resistance against Echinostoma caproni (Trematoda) secondary infections in mice is not dependent on the ileal protein production

Echinostoma caproni (Trematoda: Echinostomatidae) is an intestinal trematode, which has been widely employed to investigate the factors determining the rejection of intestinal helminths. Protein production patterns of intestinal epithelial cells are related to the infection-induced changes that determine the course of E. caproni infections. Herein, we compare the protein production profiles in the ileum of four experimental groups of mice: control; infected; dewormed and reinfected. Worm burdens were significantly lower in secondary infections, confirming the generation of partial resistance to homologous secondary infections in mice. However, quantitative comparison by 2D-DIGE showed that …

The transcriptome analysis of Strongyloides stercoralis L3i larvae reveals targets for intervention in a neglected disease.

Background: Strongyloidiasis is one of the most neglected diseases distributed worldwide with endemic areas in developed countries, where chronic infections are life threatening. Despite its impact, very little is known about the molecular biology of the parasite involved and its interplay with its hosts. Next generation sequencing technologies now provide unique opportunities to rapidly address these questions. Principal Findings: Here we present the first transcriptome of the third larval stage of S. stercoralis using 454 sequencing coupled with semi-automated bioinformatic analyses. 253,266 raw sequence reads were assembled into 11,250 contiguous sequences, most of which were novel. 8037…

Protective immunity against Echinostoma caproni in rats is induced by Syphacia muris infection.

Syphacia muris (Nematoda: Oxyuridae) is a ubiquitous nematode that commonly infects rats in the laboratory and can interfere with the development of unrelated biological assays. In this context, we analysed the effect of a patent S. muris infection in Wistar rats on a superimposed infection with the intestinal trematode, Echinostoma caproni (Trematoda: Echinostomatidae). The results indicate that in the rats, infection with S. muris induces an immunity against a subsequent infection with E. caproni, although each parasite occupies different niches in the host. Echinostoma caproni worm recovery was significantly decreased in the rats primarily infected with S. muris and, at 3 and 4 weeks pos…

The effect of glycosylation of antigens on the antibody responses against Echinostoma caproni (Trematoda: Echinostomatidae).

SUMMARYIn the present study, we analyse the effect of glycosylation inEchinostoma caproni(Trematoda: Echinostomatidae) antigens in antibody responses against the parasite in experimentally infected mice. It has been previously demonstrated that the mouse is a host of high compatibility withE. caproniand develops elevated responses of IgG, IgG1, IgG3 and IgM as a consequence of the infection, though the role of glycans in these responses remains unknown. To this purpose, the responses generated in mice against non-treated excretory/secretory antigens ofE. caproniwere compared with those observed after N-deglycosylation, O-deglycosylation and double deglycosylation of the antigens by indirect…

Zygocotyle lunata: Proteomic analysis of the adult stage

The somatic extract of Zygocotyle lunata (Trematoda: Paramphistomidae) adults collected from experimentally infected mice was investigated using a proteomic approach to separate and identify tryptic peptides from the somatic extract of Z. lunata adult worms. A shot-gun liquid chromatography/tandem mass spectrometry procedure was used. We used the MASCOT search engine (Matrix-Science) and ProteinPilot software v2.0 (Applied Biosystems) for the database search. A total of 36 proteins were accurately identified from the worms. The largest protein family consisted of metabolic enzymes. Structural, motor and receptor binding proteins and proteins related to oxygen transport were identified in th…

Helminth associations in white-toothed shrews Crocidura russula (Insectivora : Soricidae) from the Albufera Natural Park, Spain

The helminths of 218 white-toothed shrews from 29 sites in 2 biotopes in the Albufera Natural Park (Valencia, Spain) were examined from July 1990 to August 1991. An association analysis of helminths occurring at a prevalence of more than 4% was carried out for 4 species of cestodes located in the intestine (Hymenolepis pistillum, H. scalaris, H. tiara, and Pseudhymenolepis redonica) and 3 species of nematodes (Pseudophysaloptera sp. located in the stomach, Stammerinema rhopocephala larvae in the intestine and abdominal cavity, and Porrocaecum sp. in the thoracic and abdominal cavities). Bivariate (species pairs) versus multivariate analyses (associations within the entire set of species) we…

Altered Protein Expression in the Ileum of Mice Associated with the Development of Chronic Infections with Echinostoma caproni (Trematoda)

Background Echinostoma caproni (Trematoda: Echinostomatidae) is an intestinal trematode that has been extensively used as experimental model to investigate the factors determining the expulsion of intestinal helminths or, in contrast, the development of chronic infections. Herein, we analyze the changes in protein expression induced by E. caproni infection in ICR mice, a host of high compatibility in which the parasites develop chronic infections. Methodology/Principal Findings To determine the changes in protein expression, a two-dimensional DIGE approach using protein extracts from the intestine of naïve and infected mice was employed; and spots showing significant differential expression…

Differential expression and glycosylation of proteins in the rat ileal epithelium in response to Echinostoma caproni infection.

Echinostoma caproni (Trematoda: Echinostomatidae) is an intestinal trematode that has been used as experimental model to investigate the factors determining the expulsion of intestinal helminths. We analyze the changes in the protein expression and glycosylation induced by E. caproni in Wistar rat, a host of low compatibility in which the parasites are rapidly rejected. To determine the changes in protein expression, two-dimensional difference gel electrophoresis was employed using protein extracts from the intestine of naïve and infected rats. The patterns of glycosylation were analyzed by lectin blotting. Those spots showing differential expression or glycosylation were analyzed by mass s…

Antibody trapping: A novel mechanism of parasite immune evasion by the trematode Echinostoma caproni

Background Helminth infections are among the most prevalent neglected tropical diseases, causing an enormous impact in global health and the socioeconomic growth of developing countries. In this context, the study of helminth biology, with emphasis on host-parasite interactions, appears as a promising approach for developing new tools to prevent and control these infections. Methods/Principal findings The role that antibody responses have on helminth infections is still not well understood. To go in depth into this issue, work on the intestinal helminth Echinostoma caproni (Trematoda: Echinostomatidae) has been undertaken. Adult parasites were recovered from infected mice and cultured in vi…

Development of an antibody-based capture enzyme-linked immunosorbent assay for detecting echinostoma caproni (trematoda) in experimentally infected rats: kinetics of coproantigen excretion

The present study reports on the development of a coproantigen capture enzyme-linked immunosorbent assay (ELISA) for detecting Echinostoma caproni in experimentally infected rats. The capture ELISA was based on polyclonal rabbit antibodies that recognize excretory–secretory (ES) antigens. The detection limit of pure ES was 3 ng/ml in sample buffer and 60 ng/ml in fecal samples. The test was evaluated using a follow-up of 10 rats experimentally infected with 100 metacercariae of E. caproni, and the results were compared with those of other diagnostic methods such as parasitological examination and antibody titers determined by indirect ELISA. Coproantigens were detected in all the infected r…

Interleukin-25 Induces Resistance Against Intestinal Trematodes

AbstractEchinostoma caproni is an intestinal trematode that has been extensively used as an experimental model to investigate the factors determining the resistance to intestinal helminths or the development of chronic infections. ICR mice are permissive hosts for E. caproni in which chronic infections are developed, concomitantly with local Th1 responses, elevated levels of local IFN-γ, inflammation and antibody responses. However, mice develop partial resistance to homologous challenge infections after cure of a primary infection, which converts this subject into an adequate model for the study of the mechanisms generating resistance against intestinal helminths. The purpose of the presen…

Additional file 5 of Interleukin-25-mediated resistance against intestinal trematodes does not depend on the generation of Th2 responses

Additional file 5: Fig. S4. Treatment of IL-25-treated-mice with mα-IL-4Rα or rIL-13Rα2 reduces STAT6 activation. Indirect immunofluorescence with anti-STAT6 (red) and anti-STAT6P (red) on intestinal tissue of IL-25-treated-mice that were also treated with mα-IL-4Rα or rIL-13Rα2 at 2 weeks post-primary infection. Scale bar: 30 μm.

Additional file 4 of Interleukin-25-mediated resistance against intestinal trematodes does not depend on the generation of Th2 responses

Additional file 4: Fig. S3. Secondary E. caproni infection induces expansion of tuft cells and GATA3 + cells. (A) Schematic representation of the experimental protocol; (B) Counts of tuft cell populations and (C) GATA3 + cells 2 weeks after primary infection (2 wppi), 2 weeks after treatment with pzq (2 wppt) and 2 weeks after secondary infection with E. caproni (2 wpsi). Vertical bars represent the standard deviation. a: significant differences with respect to naïve mice controls; b: significant differences between groups (p

Additional file 2 of Interleukin-25-mediated resistance against intestinal trematodes does not depend on the generation of Th2 responses

Additional file 2: Fig. S1. Treatment of mice with rIL-4 or rIL-13 induces a Th2 response and RELM-β overexpression in response to primary Echinostoma caproni and infection but not resistance to infection. (A) expression of cytokine mRNA in the intestinal tissue of rIL-4-treated or rIL-13-treated mice at 2 weeks post-primary infection with E. caproni; (B) expression of RELM-β mRNA in the intestinal tissue (F) of naïve mice, non-infected rIL-4- or rIL-13-treated mice and infected rIL-4- or rIL-13-treated mice at 2 weeks post-primary infection. The relative quantities (RQ) of cytokine genes are shown after normalization with β-actin and standardization of the relative amount against day 0 sam…

Additional file 3 of Interleukin-25-mediated resistance against intestinal trematodes does not depend on the generation of Th2 responses

Additional file 3: Fig. S2. Immunohistochemical images showing changes in tuft cell populations (A) and GATA3+ cells (B) 2 weeks after primary infection (2 wppi), 2 weeks after treatment with praziquantel (2 wppt) and 2 weeks after secondary infection with E. caproni (2 wpsi). Scale bar: 10 μm.