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Echinostoma caproni (Trematoda: Echinostomatidae) is an intestinal trematode with no tissue phases in the definitive host that has been extensively used as an experimental model to study the factors that determine resistance against intestinal helminths. In E. caproni infections in mice, interleukin-25 (IL-25) plays a critical role and it is required for the resistance to infection. However, little is known on the factors that determine its production. Primary E. caproni infection in mice is characterized by the development of chronic infections and elevated worm recovery, in relation to a local Th1 response with elevated production of interferon-γ. However, partial resistance against secondary E. caproni infections in ICR (Institute of Cancer Research) mice is developed after the chemotherapeutic cure of a primary infection and the innately produced IL-25 after pharmacological treatment. In this paper, we analyse the potential role of intestinal microbiota in the production of IL-25, and the subsequent resistance to infection. For this purpose, we analysed the production of IL-25 under conditions of experimental dysbiosis and also the changes in the resident microbiota in primary infections, pharmacological curation and secondary infections. The results obtained showed that resident microbiota play a major role in the production of IL-25 and the appearance of members of the phylum Verrucomicrobia as a consequence of the curation of the primary infection could be related to the partial resistance to secondary infection.

In the present paper, we review two of the most neglected intestinal food-borne trematodiases: echinostomiasis, caused by members of the family Echinostomatidae, and gastrodiscoidiasis produced by the amphistome Gastrodiscoides hominis. Both parasitic infections are important intestinal food-borne diseases. Humans become infected after ingestion of raw or insufficiently cooked molluscs, fish, crustaceans, amphibians or aquatic vegetables. Thus, eating habits are essential to determine the distribution of these parasitic diseases and, traditionally, they have been considered as minor diseases confined to low-income areas, mainly in Asia. However, this scenario is changing and the population at risk are currently expanding in relation to factors such as new eating habits in developed countries, growing international markets, improved transportation systems and demographic changes. These aspects determine the necessity of a better understanding of these parasitic diseases. Herein, we review the main features of human echinostomiasis and gastrodiscoidiasis in relation to their biology, epidemiology, immunology, clinical aspects, diagnosis and treatment.

The autonomous Valencian Community (Spain) has experienced intense population growth with economic difficulties or deprivation in basic goods, ranking as the sixth Spanish autonomous region with the highest percentage of a population at risk of poverty or social exclusion. The objective of this work is to assess the level of enteroparasites in a Valencian population that meets certain deprivation conditions. A coproparasitological analysis was carried out in 460 users (children and adult relatives) of the 3 Casa Caridad schools in the province of Valencia. The parasite prevalence reached 31.7%, with a higher frequency of pathogens/potentially pathogenic species (66.4%) than non-pathogenic species (33.5%), although symptoms only appeared in 10.3% of those with pathogens/potentially pathogenic species. Of those parasitized, the presence of pathogens/potentially pathogenic species reached 20.6% in individuals living in crowded conditions and 17.5% in those living with pets. Presenting pathogens/potentially pathogenic species infection increased almost fourfold in those of southern European origin. In family groups, infection occurred among all their members, showing interpersonal parasitic transmission linked to both material deprivation and a lack of health education. Improving epidemiological surveillance, health education, and hygiene/sanitation facilities is essential to reduce or eliminate parasitic transmission among those who suffer from certain deprivation conditions.

Antibody trapping is a recently described strategy for immune evasion observed in the intestinal trematode Echinostoma caproni, which may aid to avoiding the host humoral response, thus facilitating parasite survival in the presence of high levels of local-specific antibodies. Parasite-derived peptidases carry out the degradation of trapped antibodies, being essential for this mechanism. Herein, we show that cathepsin-like cysteine endopeptidases are active in the excretory/secretory products (ESPs) of E. caproni and play an important role in the context of antibody trapping. Cysteine endopeptidase activity was detected in the ESPs of E. caproni adults. The affinity probe DCG-04 distinguished a cysteine peptidase band in ESPs, which was specifically recognized by an anti-cathepsin L heterologous antibody. The same antibody localized this protein in the gut and syncytial tegument of adult worms. Studies with cultured parasites showed that in vivo-bound antibodies are removed from the parasite surface in the absence of peptidase inhibitors, while addition of cathepsin L inhibitor prevented their degradation. These results indicate that cathepsin L-like peptidases are involved in the degradation of surface-trapped antibodies and suggest that cysteine peptidases are not only crucial for tissue-invading trematodes, but they can be equally relevant at the parasite-host interface in gut-dwelling flukes.

Background: Echinostoma caproni (Trematoda: Echinostomatidae) is an intestinal trematode, which has been widely employed to investigate the factors determining the rejection of intestinal helminths. In this sense, several studies have shown that IL-25 is essential for the development of resistance against E. caproni in mice. In fact, treatment of mice with recombinant IL-25 generates resistance against primary E. caproni infection. However, the mechanisms by which IL-25 induces resistance remain unknown.Methods: To study the mechanisms responsible for resistance elicited by IL-25, we analyze the ileal proteomic changes induced by IL-25 in mice and their potential role in resistance. To this purpose, we compare the protein expression profiles in the ileum of four experimental groups of mice: naïve controls; E. caproni-infected mice; rIL-25-treated mice; and rIL-25-treated mice exposed to E. caproni metacercariae.Results: Quantitative comparison by 2D-DIGE showed significant changes in a total of 41 spots. Forty of those spots validated protein spots were were identified by mass spectrometry corresponding to 24 proteins.Conclusions: The analysis of differentially expressed proteins indicates that maintenance of the intestinal epithelial homeostasis and the regulation of proliferation and cell death are the most affected processes that appears to be related to the resistance to infection. These results provide new insights into the proteins involved in the regulation of tissue homeostasis after intestinal infection and its transcendence in resistance.

Additional file 4: Table S1. Details of the computational comparison of protein expression profiles of intestinal epithelial cells isolated from control, control inoculated with rIL-25, infected and infected in presence of rIL-25 mice performed with the EDA module of DeCyder software (GE Healthcare). Manually validated spots displaying significant statistical differences (P < 0.01 in one-way ANOVA) are pairwise comparisons of groups. Comparisons are based on the presence or absence of rIL-25, i.e. infected and control against infected in the presence of rIL25, and control inoculated with rIL-25 mice. For each spot in each pair, the fold-change and average normalised volumes (ANV) are shown.

Echinostoma caproni (Trematoda: Echinostomatidae) is an intestinal trematode, broadly employed to study the host-dependent mechanisms that govern the evolution of intestinal helminth infections. Resistance against E. caproni homologous secondary infections has been reported in mice and appears to be related to the generation of a local Th2 response, whereas Th1 responses promote the development of chronic primary infections. Herein, the ability of E. caproni to modulate its secretome according to the host environment is investigated. A two-dimensional differential in gel electrophoresis (2D-DIGE) analysis was performed to elucidate changes in the excretory/secretory products of E. caproni adults after primary and secondary infections in mice. A total of 16 protein spots showed significant differences between groups, and 7 of them were successfully identified by mass spectrometry. Adult worms exposed to a primary infection appear to upregulate proteins involved in detoxification (aldo-keto reductase), stress response (GroEL), and enhancement of parasite survival (acetyl-CoA A-acetyltransferase and UTP-glucose-1-phosphate urydyltransferase). In contrast, any protein was found to be significantly upregulated after secondary infection. Upregulation of such proteins may serve to withstand the hostile Th1 environment generated in primary infections in mice. These results provide new insights into the resistance mechanisms developed by the parasites to ensure their long-term survival.

The current strategy for the control of helminth infections relies on chemotherapy. However, resistance appearance is promoting the necessity of developing new drugs against trematodes. Herein, potential trematocidal effects of garlic (Allium sativum) are investigated in the context of intestinal foodborne trematodes, employing the Echinostoma caproni-mouse model. Daily administration of dietary doses of garlic was conducted in three groups of mice: (i) before infection (prophylaxis), (ii) after infection (therapeutic) and (iii) both, before and after infection (continuous). A fourth group of mice, not exposed to garlic, was used as control. No differences in worm recovery, fecundity and local cytokine expression profiles were found with respect to control infections. However, considerable alterations in tegument structure, including swelling, furrowing, vacuolization and changes in secretory bodies were detected in garlic-exposed parasites using scanning and transmission electron microscopy. Protein secretion was markedly reduced in response to garlic, whereas up-regulation of several proteins, such as major vault protein and tER-ATPase, was observed in treated worms. The results presented herein provide new insights in the anthelminthic activity of bioactive garlic compounds and the manner that parasites respond to toxins.

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 with 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 transportation systems, new eating habits in developed countries and demographic changes. These factors make it necessary to better understand intestinal trematode infections. This chapter describes the main features of human intestinal trematodes in relation to their biology, epidemiology, host-parasite relationships, pathogenicity, clinical aspects, diagnosis, treatment, and control.

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 trade of foods, and changes in alimentary habits. Although efforts have been made for the development of immunological and molecular techniques, the detection of eggs through parasitological techniques remains as the gold standard for the diagnosis of trematodiases. In this chapter, we review the current status of knowledge on diagnostic techniques used when examining feces, urine, and sputum and also analyze the most relevant characteristics used to identify eggs with a quick key for the identification of eggs.

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 trade of foods, and changes in alimentary habits. Although efforts have been made for the development of immunological and molecular techniques, the detection of eggs through parasitological techniques remains as the gold standard for the diagnosis of trematodiases. In this chapter, we review the current status of knowledge on diagnostic techniques used when examining feces, urine, and sputum and also analyze the most relevant characteristics used to identify eggs with a quick key for the identification of eggs.

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 protein production profile is similar in control and dewormed mice, and after primary and secondary E. caproni infections. These results showed that, unexpectedly, protein production changes in E. caproni infections are not responsible of resistance development. Fifty-one protein spots were differentially produced between control/treated and infected/reinfected mice and 37 of them were identified by mass spectrometry. The analysis of differentially abundant proteins indicate that cell metabolism and the regulation of proliferation and cell death are the most affected processes after primary and secondary E. caproni infections. These results provide new insights into the proteins involved in the regulation of tissue homeostasis after intestinal infection.Intestinal helminthiases are highly prevalent parasitic infections with about 1 billion people infected worldwide. In this scenario, better understanding of host-parasite relationships is needed to elucidate the factors that determine intestinal helminth rejection. The intestinal trematode Echinostoma caproni has been broadly employed in this field, with resistance against secondary homologous infections reported in mice. In this paper, new insights are provided in the regulation of tissue homeostasis after intestinal infection. The unexpected lack of an altered pattern of ileal protein production associated to resistance development suggests that this resistance depends on rapid changes, affecting the early establishment of worms, rather than the activation of later effector mechanisms. These results may contribute to the development of new control tools for the management of these parasitic infections.

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 vitro. Double indirect immunofluorescence at increasing culture times was done to show that in vivo-bound surface antibodies become trapped within a layer of excretory/secretory products that covers the parasite. Entrapped antibodies are then degraded by parasite-derived proteases, since protease inhibitors prevent for antibody loss in culture. Electron microscopy and immunogold-labelling of secreted proteins provide evidence that this mechanism is consistent with tegument dynamics and ultrastructure, hence it is feasible to occur in vivo. Secretory vesicles discharge their content to the outside and released products are deposited over the parasite surface enabling antibody trapping. Conclusion/Significance At the site of infection, both parasite secretion and antibody binding occur simultaneously and constantly. The continuous entrapment of bound antibodies with newly secreted products may serve to minimize the deleterious effects of the antibody-mediated attack. This mechanism of immune evasion may aid to understand the limited effect that antibody responses have in helminth infections, and may contribute to the basis for vaccine development against these highly prevalent diseases., Author summary Helminthiases are highly prevalent neglected tropical diseases, affecting millions of people worldwide, mainly in the poorest regions. The lack of vaccines against these infections is one of the major constraints in the current parasitology and massive efforts are being done in that direction. Herein, we present a potential mechanism for parasite immune evasion consisting in trapping of surface-bound antibodies within the excretory/secretory products that are deposited over the parasite. This mechanism is aided by parasite-derived proteases, well documented virulence factors that degrade the entrapped antibodies. Altogether, this parasite strategy may serve to minimize the antibody-mediated response and promote the development of chronic infections. The present study has been done using the model trematode Echinostoma caproni, though is expected to work in other helminths, even in other groups of extracellular pathogens. This opens new expectative to better understanding of host-parasite interactions and susceptibility to helminth infections. Therefore, the results presented in this manuscript may contribute to the basis of anti-helminth vaccine development.

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, paying particular attention to the earliest events of the immune cascade which eventually lead to either susceptibility or resistance to infection.

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 genes in the case of Naegleria and Balamuthia genera, respectively. In the case of positive samples of Acanthamoeba, strains were further classified at the genotype level by sequencing the diagnostic fragment 3 (DF3) region located in the 18S rDNA gene as previously described. Sappinia sp. was not isolated during the study and thus, no molecular analysis was performed for this genus. The obtained results revealed the presence of Acanthamoeba (genotypes T3 and T4), Naegleria fowleri, and Balamuthia mandrillaris. To the best of our knowledge, this is the first report demonstrating the presence of FLA in water bodies from Guinea-Bissau and the first report on the isolation of Balamuthia mandrillaris from environmental sources in Africa.

In the present paper, we assess the relationship between the expression of IFN-γ and the development of clinical signs in Echinostoma caproni-infected mice. For this purpose, we studied the course of the infection in three mouse strains: ICR (CD-1®) (a host of high compatibility with E. caproni), BALB/c (a prototypical Th2 strain), and BALB/c deficient for IFN-γ mice (IFN-γ(-/-)). Infection in ICR mice is characterized by the elevated expression of IFN-γ and iNOS in the intestine concomitantly with the lack of clinical signs. In contrast, the infection was more virulent in BALB/c and IFN-γ-deficient mice that developed a severe form of the disease together with the absence of IFN-γ expression. The disease was more severe in IFNγ(-/-) mice in which the disease was lethal during the few first weeks of the infection. The analysis of different parameters of the infection in each host strain showed that most of the features were similar in the three mouse strains, suggesting the IFN-γ plays a central role in that protection against severe disease. Thus, IFN-γ seems to play a dichotomous role in the infection facilitating the parasite establishment, but it may also benefit mice since it protects the mice from morbidity and mortality induced by the parasite.

Echinostoma 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 present study was to compare the immune response induced in primary and secondary infections to elucidate the factors determining the different outcome of the infection in each type of infection. The results obtained indicate that susceptibility is determined by the lack of IL-25 expression in response to primary infection. In contrast, infection in an environment with elevated levels of IL-25, as occurs in challenge infection, results in a Th2 phenotype impairing parasite survival. This was confirmed by treatment of naïve mice with exogenous IL-25 and subsequent infection. Changes induced in goblet cell populations and mucin glycosylation could be implicated in resistance to infection.

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 performed. Results A total of 19 differential protein spots were identified (14 overexpressed in mice and 5 overexpressed in rats). The establishment of chronic infections in mice is mainly associated with the overexpression by adult worms of antioxidant and detoxifying enzymes (e.g. glutathione S-transferase, hydroxyacylglutathione hydrolase, thiopurine S-transferase, etc.) and metabolic enzymes like enolase, leucine aminopeptidase or malate dehydrogenase. However, the overexpression of cathepsin L and the structural protein actin observed in worms isolated from rats seems not to be effective for the colonization of the intestinal mucosa of this host. Conclusions The observed differences suggest that protein expression and/or release is modulated by the local environment generated inside the host and provide useful insights in regards to the resistance mechanisms developed by parasites to ensure their long-term survival. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1465-x) contains supplementary material, which is available to authorized users.

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 the somatic extract of Z. lunata. This is the first study that attempts to identify the proteome of Z. lunata. However, more work is needed to improve our knowledge of trematodiasis in general and more specifically to have a better understanding about host-parasite relationships in infections with paramphistomes.

Human beings can be parasitized by various species of intestinal amoebae. Entamoeba histolytica is the only intestinal amoeba recognized to be pathogenic, while other amoeba species, E. dispar, E. moshkovskii, E. hartmanni, E. coli, E. polecki, Endolimax nana and Iodamoeba buetschlii are considered to be non-pathogenic. The aim of this review is to synthesize the main morphological characteristics of the trophozoite and cyst stages of each amoeba as the basis for precise microscopical diagnosis. The difficulty of morphological differentiation among species included in the so-called "Entamoeba complex" entails the use of immunological and molecular diagnoses. In addition, a summary of basic epidemiological, therapeutic and prophylactic aspects of these non-pathogenic amoebae is provided. All of these aspects are crucial since these amoebae are usually found to be present in human coproparasitological analyses and must be differentiated from the pathogenic species E. histolytica. Furthermore, they can be used as suitable biological tags of the hygienic state of the environment and the health and hygiene measures of the population.

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 observed. We detected a greater level of actin gene expression in the adults collected from rats. These facts suggest that the low compatible host induces an increased turnover of tegumentary spines.

The excretory/secretory proteome of Echinostoma caproni (Trematoda: Echinostomatidae) adults collected from experimentally infected mice was investigated using a proteomic approach. We performed a shot-gun liquid chromatography/tandem mass spectrometry for the separation and identification of tryptic peptides from the excretory/secretory products of E. caproni adult worms. Database search was performed using MASCOT search engine (Matrix-Science) and ProteinPilot software v2.0 (Applied Biosystems). A total of 39 parasite proteins were accurately identified. Strikingly, metabolic enzymes, and particularly glycolytic enzymes, constituted the largest protein family in the excretory/secretory proteome of E. caproni adult worms. Moreover, representative proteins involved in parasite structure, response against stress, chaperones, calcium-binding, and signal transduction were also identified. This work extends our knowledge of host-parasite relationships in the E. caproni-rodent model that is extensively used to analyze the factors determining the intestinal helminth rejection. Consequently, information on many proteins may be useful to better understand the molecular basis that determines the survival of this parasite in the definitive host.

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 were analyzed by mass spectrometry. A total of 37 spots were identified differentially expressed in infected mice (10 were found to be over-expressed and 27 down-regulated). These proteins were related to the restoration of the intestinal epithelium and the control of homeostatic dysregulation, concomitantly with mitochondrial and cytoskeletal proteins among others. Conclusion/Significance Our results suggests that changes in these processes in the ileal epithelium of ICR mice may facilitate the establishment of the parasite and the development of chronic infections. These results may serve to explain the factors determining the development of chronicity in intestinal helminth infection., Author Summary Intestinal helminth infections are among the most prevalent parasitic diseases and about 1 billion people are currently infected with intestinal helminths. Incidence of intestinal helminth infections is high due to both socio-economic factors that facilitates continuous re-infections and the lack of effective vaccines. In this context, further knowledge on the host-parasite relationships is required to elucidate the factors that determine the expulsion of the intestinal helminths or, in contrast, the chronic establishment of the infections. Echinostoma caproni (Trematoda) is an intestinal trematode that has been extensively used as experimental model to investigate these factors. Depending on the host species. E. caproni is rapidly rejected or develops chronic infections. Herein, we analyze the changes in protein expression induced by E. caproni infection in a host in which the parasites develop chronic infections. These data may serve to get a better understanding of the factors determining the development of chronic intestinal infections. A total of 37 spots were identified differentially expressed. These proteins were related to the restoration of the intestinal epithelium and the control of homeostatic dysregulation, mitochondrial and cytoskeletal proteins among others. This suggests that the changes in these processes in the intestinal mucosa may facilitate the development of chronic infections.

The transmission of harmful pathogens by arthropods is an increasing health concern. More concretely, flies are known to be able to transmit the infectious agent mechanically.The present work shows a case report occurred from foodservice establishments where were isolated and identified, at the first time, Megaselia spp. in the food preparation place. Furthermore, microorganisms were analyzed from these flies.It is based in entomological and microbiological analysis.Mesophilic aerobic flora and Enterobacteriaceae were found in all the samples, exceeding the limits established from food commodities on 41.7% (5/12) for mesophilic aerobic bacteria and 66.7% (8/12) for Enterobacteriaceae. Furthermore, 25% (3/12) of analyzed flies were found positive to Escherichia coli, data that can be linked with the microbiological food results. The most surprising results were the presence of S. aureus in 66.7% (8/12) of the analyzed flies.A binomial relationship among Megaselia spp. and bacteria is demonstrated being an important study to demonstrate that must be checked more hygienically measurement in foodservice.Introducción: la transmisión de patógenos por insectos es una creciente preocupación para la salud pública. Más concretamente, las moscas son conocidas por ser capaces de transmitir el agente infeccioso mecánicamente. Objetivo: el presente trabajo muestra un estudio en los servicios de restauración en los que se aisló por primera vez en la literatura Megaselia spp, detectándose la presencia de microorganismos en estas moscas. Método: se basa en análisis microbiológicos y entomológicos. Resultados: la presencia de aerobios mesófilos y Enterobacteriaceae se han encontrado en todas las muestras, superando los límites establecidos en el 41,7% (5/12) para las bacterias aerobias mesófilas y el 66,7% (8/12) para Enterobacteriaceae. Por otra parte, en el 25 y 66,7% de las moscas analizadas se detectó la presencia de Escherichia coli y Staphylococcus aureus, respectivamente. Conclusiones: hay un binomio entre la presencia de microorganismos y Megaselia spp., lo que demuestra la importancia de mantener una vigilancia más estricta en las medidas higiénico-sanitarias en los servicios de restauración.

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 transmission fitness of a parasite in different definitive host species. Moreover, variations of the Experimental Transmission Success over the course of the infection were calculated by the use of the Weekly Experimental Transmission Success (TMW). Overall, considering the complete duration of the experiment, the TM of E. friedi using rats as definitive hosts was 0.68 infected snails/metacercaria. However, positive values of the TMW were only obtained from 2 to 4 wk post-infection, with a maximum during the third wk post-infection. When comparing the TM values of E. friedi in rats with those calculated in hamsters on the basis of previously published data, E. friedi appears to be more appropriate to move through this portion of its life cycle when using hamsters (Mesocricetus auratus) as the final host than rats. Toledo Navarro, Rafael, Rafael.Toledo@uv.es ; Carpena Hernandez, Ines, Ines.Carpena@uv.es ; Espert Fernandez, Ana M., Ana.M.Espert@uv.es ; Sotillo Gallego, Javier, Javier.Sotillo@uv.es ; Esteban Sanchis, Jose Guillermo, Jguillermo.Esteban@uv.es

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. However, the response seems to be mainly directed against excretory-secretory antigens. We have also defined by Western blot 11 and 7 major antigenic polypeptides in SoP and ESP, respectively, that were recognized by sera from experimentally infected rats. Only 2 of these polypeptides were common to both types of antigens. A total of 9 antigenic polypeptides, ranging from 24 to 137 kDa, were found to be characteristic of SoP, whereas 5 polypeptides, weighing from 28 to 117 kDa, were characteristic of ESP. The kinetics of antibody production against discrete polypeptides composing both types of antigens were determined during the course of the infection.

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 ELISA and western blot. Our results suggest thatE. caproni-expressed glycans play a major role in the modulation of the immune responses. The results obtained indicate that IgG subclass responses generated in mice againstE. caproniare essentially due to glycoproteins and may affect the Th1/Th2 biasing. The reactivity significantly decreased after any of the deglycosylation treatments and the N-glycans appears to be of greater importance than O-glycans. Interestingly, the IgM response increased after N-deglycosylation suggesting that carbohydrates may mask peptide antigens.

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 transportation systems, new eating habits in developed countries and demographic changes. These factors make it necessary to better understand intestinal trematode infections. This chapter describes the main features of human intestinal trematodes in relation to their biology, epidemiology, host–parasite relationships, pathogenicity, clinical aspects, diagnosis, treatment and control.

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 spectrometry. A total of 33 protein spots differentially expressed were identified (26 were found to be over-expressed and 7 down-regulated). Moreover, E. caproni induced changes in the glycosylation status of 8 proteins that were successfully identified. Most of these proteins were related to the cytoskeleton and the maintenance of the functional integrity of the ileal epithelium. This suggests that the regeneration of the intestinal tissue is a major effector mechanism responsible for the early expulsion of this helminth. Furthermore, several proteins involved in the energy metabolism were also altered in the ileum of rats as a consequence of the E. caproni infection.Our analysis provides essential new insights in the factors determining the natural expulsion of intestinal parasitic helminths from their hosts. The results obtained contribute to a better understanding of the effective mechanisms involved in the defense against the intestinal helminths. The identification of proteins in the intestine that become modified in their expression or glycosylation in hosts in which the parasite is rapidly rejected may serve for the development of tools for the control of these infections.

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, transcriptome and proteome is likely to have an important impact on the development of control strategies for intestinal helminths. We present the first transcriptome of the adult stage of Echinostoma caproni using 454 sequencing coupled to a semi-automated bioinformatic analyses. 557,236 raw sequence reads were assembled into 28,577 contiguous sequences using iAssembler. 23,296 putative proteins were characterized based on homology, gene ontology and/or biochemical pathways. Comparisons of the transcriptome of E. caproni with those of other trematodes revealed similarities in the transcription pattern of molecules inferred to have key roles in parasite–host interactions. Enzymatic proteins like kinases and peptidases were abundant. Of the 3415 predicted excretory/secretory proteins compiled (including non-classical secretory proteins), 180 different proteins were confirmed by proteomic analysis. Potential drug targets were also identified. Biological significance In this study the first transcriptome of the adult stage of E. caproni is presented and compared to those of other trematodes revealing similarities in transcription for molecules inferred to have key roles in parasite–host interactions. 3415 predicted excretory/secretory proteins were compiled, being 180 different proteins confirmed by proteomic analysis. The current transcriptome data increased by nine times the number of previous protein identifications. In addition, potential drug targets for this parasite were identified. The present dataset should provide a solid foundation for future fundamental genomic, proteomic, and metabolomic explorations of E. caproni, as well as a basis for applied outcomes, such as the development of novel methods of intervention against this model organism and related parasites.

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 post-primary infection, the rats primarily infected with S. muris were refractory to the challenge infection with E. caproni. We observed that the main alterations induced by S. muris in the niche of E. caproni (ileum) that may be the cause of the resistance are: (i) a local antibody response with elevated levels of mucosal IgA, IgE, IgG, IgG1 and IgG2a that cross-react with E. caproni antigens; (ii) development of a biased Th17/Th2 phenotype; and (iii) changes in the glycosylation of ileal mucins. This indicates that S. muris induces distant alterations to the ileum of rats affecting the development of other helminth species. Apart from the interest of these results in the study of the interactions between helminths in a single host, it has been demonstrated that pinworm infections may interfere in non-related experiments.

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 putative proteins were characterized based on homology, gene ontology and/ or biochemical pathways. Comparison of the transcriptome of S. strongyloides with those of other nematodes, including S. ratti, revealed similarities in transcription of molecules inferred to have key roles in parasite-host interactions. Enzymatic proteins, like kinases and proteases, were abundant. 1213 putative excretory/secretory proteins were compiled using a new pipeline which included non-classical secretory proteins. Potential drug targets were also identified. Conclusions: Overall, the present dataset should provide a solid foundation for future fundamental genomic, proteomic and metabolomic explorations of S. stercoralis, as well as a basis for applied outcomes, such as the development of novel methods of intervention against this neglected parasite., This work was supported by project PS09/02355 from the Fondo de Investigacio´n Sanitaria (FIS), Spanish Ministry of Science and Innovation (Madrid, Spain) and FEDER and project PROMETEO/2009/081 from Conselleria d’Educacio´ , Generalitat Valenciana (Valencia, Spain). GG would like to acknowledge Macquarie University for an Australian Post-graduate Award scholarship. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Human beings can be parasitized by various species of intestinal amoebae. Entamoeba histolytica is the only intestinal amoeba recognized to be pathogenic, while other amoeba species, E. dispar, E. moshkovskii, E. hartmanni, E. coli, E. polecki, Endolimax nana and Iodamoeba buetschlii are considered to be non-pathogenic. The aim of this review is to synthesize the main morphological characteristics of the trophozoite and cyst stages of each amoeba as the basis for precise microscopical diagnosis. The difficulty of morphological differentiation among species included in the so-called "Entamoeba complex" entails the use of immunological and molecular diagnoses. In addition, a summary of basic epidemiological, therapeutic and prophylactic aspects of these non-pathogenic amoebae is provided. All of these aspects are crucial since these amoebae are usually found to be present in human coproparasitological analyses and must be differentiated from the pathogenic species E. histolytica. Furthermore, they can be used as suitable biological tags of the hygienic state of the environment and the health and hygiene measures of the population.

The Echinostoma caproni-mice system is extensively used as an experimental model for the study of the factors involved in the establishment of chronic intestinal helminth infections. Although several parameters of the immunobiology of the host-parasite system have been studied in detail, the current knowledge of the cellular responses in these infections is still scarce. In the present paper, we analyze the kinetics of the circulating CD3(+) and CD19(+) cell populations and the different T-cell phenotype profiles in mice experimentally infected with E. caproni. Whereas the CD3(+) populations remained stable during the complete experiment, a marked increase in CD19(+) cells was observed from 4 weeks post-infection and beyond. Similarly, a marked increase in CD8(+) cell populations was observed in the 2 week post-infection. Our results show that E. caproni infection in mice alters the peripheral lymphoid cell populations, which may be important to determine the course of the infection. In this sense, CD8(+) cells can be essential in relation to their role as a source of IFN-γ.

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 parasite at the spleen, Peyer's patches and mesenteric lymph node did not show clear differences with regard to the mice. However, the response in the intestine was markedly different. In rats, a Th2 response with increase in the levels of IL-5, IL-6 and IL-13 expression was detected. According to these results, the local production of IFN-γ and the local inflammatory responses with neutrophilic infiltration are associated with the development of chronic infections, whereas the worm expulsion is related with the development of Th2 responses and appears to be based on effects on non-bone narrow-derived cells.

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-independent antigens, and slight increases of total IgG, IgG1 and IgG2a. At the intestinal level, increases of IgM and IgA levels were observed in mice. In regard to IgG subclasses, increases in both IgG1 and IgG2a were detected. Later decreases to normal values in IgG2a were also detected. In rats, only increases in total IgG and IgG2a were found. According to our results the development of long-lasting E. caproni infections in mice appears to be associated with a dominance of Th2 responses at the systemic level and balanced Th1/Th2 responses at the local level, characterized by initial increases in IgG1 and IgG2a levels. In contrast, the worm expulsion appears to be related to increases in local IgG2a levels.

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 study using polyclonal IgG anti-E. caproni excretory-secretory antigens demonstrated a greater level of passage of E. caproni antigens through the intestinal mucosa in hamsters than in rats, probably in relation to the greater inflammatory response. Our results indicate the fact that early inflammatory responses could be important for the establishment of E. caproni chronic infections in highly compatible hosts.

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) were performed of presence–absence and of quantitative records (influence of intensity on associations). The associations were evaluated with respect to the sex and age of the host and to the sampling date and sites. The host and environment played a limited role, and the major determinant of species assemblage was phylogenetic. Positive associations were found among both the cestodes and the nematodes, whereas negative associations were found between cestodes and nematodes. The type of life cycle was probably the second greatest determinant of species associations. Nematodes using shrews as a paratenic host or as their definitive host were both positively associated. Esteban Sanchis, Jose Guillermo, Jguillermo.Esteban@uv.es

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 remained positive until the end of the experiment in hamsters; in rats, the coproantigen levels reverted to negative values, coinciding with the loss of infection. High levels of circulating antigens were detected in hamsters from 21 DPI to the end of the study. In contrast, low levels of E. caproni seroantigens were detected in rats only. These observations may reflect the differences in local inflammatory responses induced by E. caproni in each host species. Infections with intestinal trematodes are widespread. Despite the frequency of these infections, the relationships between in- testinal trematodes and their final hosts have received little at- tention. Echinostoma caproni(Trematoda: Echinostomatidae) is an intestinal trematode that does not undergo tissue migration in its definitive host. After infection of the definitive host with E. caproni, the metacercariae excyst in the duodenum, and the juvenile parasites migrate to the posterior third of the small