E Claerebout

Ghent University, Gand, Flanders, Belgium

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Publications (145)351.16 Total impact

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    ABSTRACT: Human wastewater and livestock can contribute to contamination of surface water with Cryptosporidium and Giardia. In countries where a substantial proportion of drinking water is produced from surface water, e.g., Belgium, this poses a constant threat on drinking water safety. Our objective was to monitor the presence of Cryptosporidium and Giardia in different water catchment sites in Belgium and to discriminate between (oo)cysts from human or animal origin using genotyping. Monthly samples were collected from raw water and purified drinking water at four catchment sites. Cryptosporidium and Giardia were detected using USEPA method 1623 and positive samples were genotyped. No contamination was found in purified water at any site. In three catchments, only low numbers of (oo)cysts were recovered from raw water samples (<1/liter), but raw water samples from one catchment site were frequently contaminated with Giardia (92 %) and Cryptosporidium (96 %), especially in winter and spring. Genotyping of Giardia in 38 water samples identified the presence of Giardia duodenalis assemblage AI, AII, BIV, BIV-like, and E. Cryptosporidium andersoni, Cryptosporidium suis, Cryptosporidium horse genotype, Cryptosporidium parvum, and Cryptosporidium hominis were detected. The genotyping results suggest that agriculture may be a more important source of surface water contamination than human waste in this catchment. In catchment sites with contaminated surface water, such as the Blankaart, continuous monitoring of treated water for the presence of Cryptosporidium and Giardia would be justified and (point) sources of surface water contamination should be identified.
    Environmental Monitoring and Assessment 02/2015; 187(2):4157. · 1.68 Impact Factor
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    ABSTRACT: Giardia and Cryptosporidium are important causes of diarrhoea in Bangladesh. The high prevalence of both parasites in humans and cattle in rural Bangladesh and the common use of water ponds by village inhabitants and their animals suggest a potential for zoonotic transmission. Direct transmission of Giardia and Cryptosporidium between cattle and their handlers and indirect transmission through water ponds was investigated. Faecal/stool samples were collected from 623 calves and 125 calf handlers in a cross-sectional survey. In two villages, water samples were collected monthly from water ponds and faecal/stool samples were collected monthly from inhabitants and their cattle. Giardia cysts and Cryptosporidium oocysts were detected in water samples and in faecal/stool samples and positive samples were genotyped, to determine their human or animal origin. The prevalence of Giardia and Cryptosporidium in calves was 22% and 5% respectively. In calf handlers, the prevalence of Giardia and Cryptosporidium was 11.2% and 3.2% respectively. Both in the cross-sectional survey and in the longitudinal study in the villages, G. duodenalis assemblage E was most prevalent in calves, while in humans assemblage AII, BIII and BIV were found. In cattle, Cryptosporidium parvum, C. bovis and C. andersoni were identified, but no Cryptosporidium sequences were obtained from humans. Giardia and Cryptosporidium were detected in 14/24 and 12/24 water samples respectively. G. duodenalis assemblage E and BIV (-like), as well as C. andersoni and C. hominis were identified. Although the presence of Giardia and Cryptosporidium in both water ponds suggests that water-borne transmission of Giardia and Cryptosporidium is possible, the genotyping results indicate that there is no significant direct or indirect (water-borne) transmission of Giardia between cattle and people in this area of rural Bangladesh. No conclusions could be drawn for Cryptosporidium, because of the low number of sequences that were obtained from human and water samples.
    PLoS ONE 01/2015; 10(2):e0118239. · 3.53 Impact Factor
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    ABSTRACT: With the increasing incidence of anthelmintic resistance worldwide, immunological control of worm infections through vaccination is often put forward as a rational and cost-effective alternative for anthelmintic drugs. In this study we report on the evaluation of a double-domain activation-associated secreted protein (ASP) purified from the excretory-secretory material of the adult stage of the small intestinal parasite Cooperia oncophora as a vaccine antigen against this parasite. In a first experiment, calves were vaccinated three times i.m. with ASP and QuilA adjuvant or with adjuvant alone, and subsequently challenged with a trickle infection of 25,000 infective larvae in total over 25 days. Vaccinated calves showed a significant reduction of 91% in their cumulative faecal egg counts and a significantly higher number of inhibited L4s present in their intestine compared with control animals. Furthermore, both female and male adult worms were significantly smaller in the vaccinated group than in the control group. In a second experiment, the vaccine antigen was further evaluated under field conditions. Calves were immunised as described above, followed by a natural challenge infection on pasture. Cooperia oncophora faecal egg counts in the vaccinated animals were reduced during the entire grazing period, resulting in a significant reduction in the cumulative faecal egg counts of 58.5%. Numbers of infective C. oncophora larvae were lower on plots grazed by vaccinated calves, with a reduction in mean pasture larval counts of 65% at housing. A significant reduction of 81.6% in total numbers of C. oncophora worms was shown in the vaccinated group compared with the control group. Taken together, the data highlight the protective capacity of the double-domain ASP protein and the possibility of controlling C. oncophora infections through vaccination. Copyright © 2014. Published by Elsevier Ltd.
    International Journal for Parasitology 12/2014; · 3.40 Impact Factor
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    ABSTRACT: Predictive models of parasite life cycles increase our understanding of how parasite epidemiology is influenced by global changes and can be used to support decisions for more targeted worm control. Estimates of parasite population dynamics are needed to parameterize such models. The aim of this study was to quantify the main life history traits of Ostertagia ostertagi, economically the most important nematode of cattle in temperate regions. The main parameters determining parasite density during the parasitic phase of O. ostertagi are (i) the larval establishment rate, (ii) hypobiosis rate, (iii) adult mortality and (iv) female fecundity (number of eggs laid per day per female). A systematic review was performed covering studies from 1962 to 2007, in which helminth-naïve calves were artificially infected with O. ostertagi. The database was further extended with results of unpublished trials conducted at the Laboratory for Parasitology of Ghent University, Belgium. Overall inverse variance weighted estimates were computed for each of the traits through random effects models. An average establishment rate (± S.E.) of 0.269 ± 0.022 was calculated based on data of 27 studies (46 experiments). The establishment rate declined when infection dose increased and was lower in younger animals. An average proportion of larvae entering hypobiosis (± S.E.) of 0.041 (± 0.009) was calculated based on 27 studies (54 experiments). The proportion of ingested larvae that went into hypobiosis was higher in animals that received concomitant infections with nematode species other than O. ostertagi (mixed infections). An average daily adult mortality (± S.E.) of 0.028 (± 0.002) was computed based on data from 28 studies (70 experiments). Adult mortality was positively correlated with infection dose. A daily fecundity (± S.E.) of 284 (± 45) eggs per female was found based on nine studies (10 experiments). The average female sex ratio of O. ostertagi based on individual animal data (n = 75) from six different studies was estimated to be 0.55. We believe that this systematic review is the first to summarize the available data on the main life history traits of the parasitic phase of O. ostertagi. In conclusion, this meta-analysis provides novel estimates for the parameterization of life cycle-based transmission models, explicitly reports measures of variance around these estimates, gives evidence for density dependence of larval establishment and adult mortality, shows that host age affects larval establishment and, to our knowledge, provides the first evidence for O. ostertagi of a female-biased sex ratio.
    International Journal for Parasitology 09/2014; · 3.40 Impact Factor
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    ABSTRACT: Giardia duodenalis and Cryptosporidium spp. are gastro-intestinal protozoa known to infect small rumi-nants. Both protozoa are also considered as a potential public health concern. The objective of this study was to deter-mine their prevalence in lambs and goat kids kept under common Mediterranean dairy husbandry systems and to identify the species and genotypes infecting these small ruminants. In total, 684 faecal samples (429 from lambs and 255 from goat kids) were collected on 21 farms in Greece and examined using a quantitative immunofluorescence assay. G. duodenalis was detected in 37.3% of the lambs and 40.4% of the goat kids. On all but one of the farms G. duodenalis was detected. Most samples were typed as a mono-infection with G. duodenalis assemblage E, both on the b-giardin gene and the triose phosphate isomerase gene. Only 10% of samples were typed as mixed assemblage A and E infections. The prevalence of Cryptosporidium spp. was 5.1% in lambs and 7.1% in goat kids. In total, 8 out of the 14 farms with a sheep flock and 7 out of the 14 farms with a goat flock were positive. Cryptosporidium parvum (subtype IId), C. ubiquitum and C. xiaoi were identified, the latter especially in goat kids. In conclusion, the results of the present study illustrate that G. duodenalis and Cryptosporidium spp. occur frequently on both sheep and goats farms. The prevalence of zoonotic genotypes or species was low, indicating a limited but existing risk for zoonotic infections. Ré sumé – Prévalence et caractérisation moléculaire de Giardia duodenalis et Cryptosporidium spp. chez les ovins et les caprins élevés dans les systèmes laitiers en Grèce. Giardia duodenalis et Cryptosporidium spp. sont des protozoaires gastro-intestinaux connus pour infecter les petits ruminants. Les deux protozoaires sont également considérés comme un risque potentiel pour la santé publique. L'objectif de cette étude était de déterminer la prévalence chez les agneaux et les chevreaux élevés dans les systèmes méditerranéens communs d'élevage laitier et d'identifier les espèces et les génotypes infectant ces petits ruminants. Au total, 684 échantillons fécaux (429 provenant d'agneaux et 255 de chevreaux) ont été collectés dans 21 exploitations en Grèce et examinés à l'aide d'un test quantitatif d'immunofluorescence. G. duodenalis a été détecté chez 37.3 % des agneaux et 40.4 % des chevreaux, dans toutes les fermes sauf une. La plupart des échantillons ont été typés comme une mono infection par l'assemblage E de G. duodenalis, en se fondant à la fois sur l'identification du gène de la b-giardine ou du gène de l'isomérase de triose phosphate. Seuls 10 % des échantillons ont été identifiés comme une combinaison d'infections par les assemblages A et E. La prévalence de Cryptosporidium spp. était de 5.1 % chez les agneaux et de 7.1 % chez les chevreaux. Au total, 8 des 14 fermes ovines et 7 des 14 fermes caprines étaient positives. Cryptosporidium parvum (sous-type IId), C. ubiquitum et C. xiaoi ont été identifiés, ce dernier en particulier chez les chevreaux. En conclusion, les résultats de cette étude montrent que G. duodenalis et Cryptosporidium spp. sont fréquemment présents chez les ovins et les caprins. La prévalence des génotypes ou espèces zoonotiques était faible, ce qui indique un risque limité bien que présent pour des infections zoonotiques.
    Parasite 09/2014; 21. · 0.82 Impact Factor
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    ABSTRACT: The objective of the present study was to evaluate the efficacy of an oral treatment with ivermectin (IVM) or moxidectin (MOX) against gastro-intestinal strongyles in naturally infected horses by performing a faecal egg count reduction test (FECRT) and by monitoring the egg reappearance period (ERP) after treatment. Therefore, a field efficacy study with a randomised complete block design for each study site was conducted, with the individual animal as the experimental unit. At least 10 study sites in Italy, Belgium and the Netherlands were selected and animals were allocated to one of two treatment groups based on the pre-treatment faecal egg counts (FEC). Animals were treated on Day 0 with an oral paste containing either IVM (at 0.2 mg/kg bodyweight) or MOX (at 0.4 mg/kg bodyweight). After treatment, faecal samples were collected at least every fortnight during 56 days after treatment with IVM and during 84 days after MOX treatment. In total, 320 horses on 32 farms were examined. The FECRT on Day 14 indicated a 100% efficacy in 59 of the 64 treatment groups and >92% efficacy in the remaining 5 groups. The ERP was decreased for at least one of the anthelmintics on 17 out of 32 study sites (15 sites or 47% for MOX and 17sites or 53% for IVM) and on 9 sites (28%) the ERP was decreased for both anthelmintics. On some of these study sites the efficacy declined at the end of the expected ERP, often with good efficacy 2 weeks earlier. Nevertheless, on 1, 3 and 5 study sites in Italy, Belgium and The Netherlands respectively, an efficacy below 90% for IVM and MOX was identified as soon as Day 42 or Day 56. In The Netherlands, the efficacy of IVM was below 90% from Day 28 or Day 35 after treatment on 1 site each. The present study reports a high efficacy of MOX and IVM in a FECRT 14 days after treatment, yet does indicate a shortened ERP for these treatments in more than half of the selected study sites.
    Veterinary Parasitology 08/2014; · 2.55 Impact Factor
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    ABSTRACT: Giardia duodenalis causes diarrhoea in humans and a wide range of mammals, including cattle. In cattle, the infection often has a chronic character. Infected calves may excrete cysts for several months, suggesting that Giardia is able to suppress and evade the immune response. In this study six calves were infected with G. duodenalis assemblage A and E and housed in an environment that allowed reinfection. Cyst excretion was monitored twice a week and blood was collected every two weeks, until decreasing cyst counts indicated the development of protective immunity. The kinetics of the circulating memory cells and serum antibodies were followed up throughout this period. Cyst excretion started 1 week post infection and remained high until week 14. Low cyst counts from week 15 p.i. onwards indicated that the calves had developed immunity. From week 5 p.i. significant proliferation of CD4+ αβ T-cells was observed after in vitro stimulation with G. duodenalis antigen. Characterisation of the proliferating CD4+ T-cells using real time qPCR showed that at the peak of antigen driven PBMC proliferation the majority of cells were CD4+ T-cells expressing IL-17 and to a lesser extent FoxP3. The cell proliferation was strongly reduced after plastic adhesion of the PBMC, suggesting a role for antigen-presenting cells. Failure to restore proliferation of depleted PBMC with Giardia-stimulated monocyte-derived dendritic cells (MoDC) and unchanged proliferation after depletion of CD21+ B-cells showed that other antigen-presenting cells than MoDC and B-cells were important for T-cell proliferation. Analysis of the antibody response indicated that serum IgG1 and IgA levels against G. duodenalis assemblage A and E increased from week 11 post infection. From the start of the antibody response, all trophozoites stained positive in an immunofluorescence assay with serum antibodies, indicating that a broad repertoire of antibodies was produced against all variant-specific surface proteins. Further research is necessary to determine which effector T-cell subset produces IL-17 and which cells play a role in antigen presentation.
    Veterinary Parasitology 03/2014; 202(3-4):145-155. · 2.55 Impact Factor
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    ABSTRACT: Giardia duodenalis is an important intestinal parasite in animals and humans. The role of dendritic cells (DC) in the initiation of the immune response against G. duodenalis is poorly documented. The aim of this study was to test the hypothesis that G. duodenalis interferes with bovine DC function. Therefore the effect of trophozoites and excretion/secretion products on bovine monocyte-derived dendritic cells (MoDC) was investigated. We assessed MoDC maturation and cytokine production of G. duodenalis stimulated MoDC and the ability of these MoDC to take up antigen and induce lymphocyte proliferation. Little or no upregulation of maturation markers CD40 and CD80 was measured, but MHCII expression was increased after stimulation with low parasite concentrations. A dose-dependent decrease of ovalbumin uptake was observed in G. duodenalis stimulated MoDC. In addition, stimulated MoDC induced proliferation of CD3(-) , γδ-T-cells and TCRαβ(+) CD4(+) and -CD8(+) T-cells. Increased transcription of TGF-β was shown in CD4(+) T-cells and increased TNF-α, TGF-β, IL-10, and IL-4 was seen in γδ-T-cells. We found no evidence that G. duodenalis has a regulatory or inhibitory effect on bovine MoDC. MoDC stimulated with G. duodenalis are functionally active and able to induce proliferation of T-cells that produce both pro- and anti-inflammatory cytokines. This article is protected by copyright. All rights reserved.
    Parasite Immunology 12/2013; · 1.85 Impact Factor
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    ABSTRACT: The purpose of the current study was to provide more information on the kinetics of the immunological changes occurring in the abomasal mucosa after single and trickle infections with the bovine parasite Ostertagia ostertagi. The time course analysis of gene expression revealed that the major changes coincided with the emergence of adult worms from the gastric glands. These changes consisted of a simultaneous upregulation of Th1 and Th2-type cytokines. In addition, a single O. ostertagi infection elicited an upregulation of the epithelial derived cytokine IL33, while TSLP expression levels were not impacted. Apart from the massive increase of inflammatory cytokines IL6, IL17 and IL21, O. ostertagi infection also elicited an upregulation of the immunosuppressors TGFB, IL10 and ARG1, as well as NK and γδ-T cell markers. Furthermore, the cytotoxic factors granulysin, perforin and granzyme B were upregulated following an O. ostertagi infection. Analysis of cytokine transcript levels in animals receiving trickle infections for 60 days showed a similar trend as observed following a single infection except for IL33, IL6, GATA-3, TBX21 and NCR1, which were no longer upregulated after trickle infections. Finally, the long trickle infections were associated with mucosal eosinophilia and mastocytosis. This article is protected by copyright. All rights reserved.
    Parasite Immunology 12/2013; · 1.85 Impact Factor
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    ABSTRACT: Infections in cattle with the gastric nematode Ostertagia ostertagi are associated with decreased acid secretion and profound physio-morphological changes of the gastric mucosa. The purpose of the current study was to investigate the mechanisms triggering these pathophysiological changes. O. ostertagi infection resulted in a marked cellular hyperplasia, which can be explained by increased transcriptional levels of signaling molecules related to the homeostasis of gastric epithelial cells such as HES1, WNT5A, FGF10, HB-EGF, AREG, ADAM10 and ADAM17. Intriguingly, histological analysis indicated that the rapid rise in the gastric pH, observed following the emergence of adult worms, cannot be explained by a loss of parietal cells, as a decrease in the number of parietal cells was only observed following a long term infection of several weeks, but is likely to be caused by an inhibition of parietal cell activity. To investigate whether this inhibition is caused by a direct effect of the parasites, parietal cells were co-cultured with parasite Excretory/Secretory products (ESP) and subsequently analyzed for acid production. The results indicate that adult ESP inhibited acid secretion, whereas ESP from the L4 larval stages did not alter parietal cell function. In addition, our data show that the inhibition of parietal cell activity could be mediated by a marked upregulation of inflammatory factors, which are partly induced by adult ESP in abomasal epithelial cells. In conclusion, this study shows that the emergence of adult O. ostertagi worms is associated with marked cellular changes that can be partly triggered by the worm's Excretory/secretory antigens.
    Veterinary Research 12/2013; 44(1):121. · 3.38 Impact Factor
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    ABSTRACT: Vital dye staining has long been used to assess viability of Cryptosporidium oocysts and Giardia cysts, with staining and enumeration in suspension. Some recent studies, however, have dried samples to microscope slides prior to staining. Here we demonstrate that this approach may considerably underestimate parasite viability in the original sample.
    Journal of microbiological methods 11/2013; · 2.43 Impact Factor
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    ABSTRACT: To evaluate faecal and clinical scores and presence of several enteropathogens possibly implicated in the development of diarrhoea in pups aged between 6 and 16 weeks independently of their health status. Pups were selected from pet shops and breeding facilities and assigned a faecal and clinical score. Standard isolation methods were used to determine presence of parasites, viruses and bacteria in faecal samples. For Escherichia coli, virulence genes were assessed by multiplex polymerase chain reaction. Fifty-six pups were included in this study. Eighteen had no diarrhoea, 22 had no significant clinical signs related to gastroenteritis. Samples were positive for Toxocara canis (n=29), Giardia duodenalis (n=35), Cystoisospora (n=22), E. coli (n=47) and Clostridium perfringens (n=20). In four E. coli positive samples, genes were detected that correlate with pathogenicity in other animal species. A significant positive correlation between the presence of T. canis and faecal score was found. Puppies obtained from a pet shop or breeding facility have a high risk of gastrointestinal disease. Furthermore, infectious agents may be present independently of faecal or clinical score. The identification of possible pathogenic E. coli strains suggests that their role in diarrhoea warrant further investigation.
    Journal of Small Animal Practice 08/2013; · 0.91 Impact Factor
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    ABSTRACT: Cooperia oncophora is one of the most common intestinal parasitic nematodes in cattle worldwide. To date, C. oncophora infections are treated using broad-spectrum anthelmintics. However, during the last decade reports of anthelmintic resistance in this parasite species have emerged worldwide, necessitating new avenues for its control, possibly through vaccination. In this frame we analyzed the adult-stage C. oncophora excretome/secretome (ES), covering both the protein and glycan components, since this fraction constitutes the primary interface between parasite and host and may hold potential vaccine candidates. Two-dimensional gel electrophoretic separation of the ES material enabled the MALDI-TOF mass spectrometry (MS)-directed identification of twelve distinct proteins, grouped in three separate molecular weight fractions: i) a high molecular weight fraction consisting of a double-domain activation-associated secreted protein (ASP), ii) a mid-molecular weight fraction predominantly containing a single-domain ASP, a thioredoxin peroxidase and innexin, and iii) a low molecular weight protein pool essentially holding two distinct low molecular weight antigens. Further MS-driven glycan analysis mapped a variety of N-glycans to the mid-molecular weight single-domain ASP, with Man6GlcNAc2 oligomannosyl glycans as the major species. The predominance of the non-glycosylated double-domain ASP in the high-molecular weight fraction renders it ideal for advancement towards vaccine trials and development.
    Journal of Proteome Research 07/2013; · 5.06 Impact Factor
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    ABSTRACT: The incidence of tick-borne diseases is increasing in Europe. Sub national information on tick distribution, ecology and vector status is often lacking. However, precise location of infection risk can lead to better targeted prevention measures, surveillance and control. In this context, the current paper compiled geolocated tick occurrences in Belgium, a country where tick-borne disease has received little attention, in order to highlight the potential value of spatial approaches and draw some recommendations for future research priorities. Mapping of 89,289 ticks over 654 sites revealed that ticks such as Ixodes ricinus and Ixodes hexagonus are largely present while Dermacentor reticulatus has a patchy distribution. Suspected hot spots of tick diversity might favor pathogen exchanges and suspected hot spots of I. ricinus abundance might increase human-vector contact locally. This underlines the necessity to map pathogens and ticks in detail. While I. ricinus is the main vector, I. hexagonus is a vector and reservoir of Borrelia burgdorferi s.l., which is active the whole year and is also found in urban settings. This and other nidiculous species bite humans less frequently, but seem to harbour pathogens. Their role in maintaining a pathogenic cycle within the wildlife merits investigation as they might facilitate transmission to humans if co-occurring with I. ricinus. Many micro-organisms are found abroad in tick species present in Belgium. Most have not been recorded locally but have not been searched for. Some are transmitted directly at the time of the bite, suggesting promotion of tick avoidance additionally to tick removal. This countrywide approach to tick-borne diseases has helped delineate recommendations for future research priorities necessary to design public health policies aimed at spatially integrating the major components of the ecological cycle of tick-borne diseases. A systematic survey of tick species and associated pathogens is called for in Europe, as well as better characterisation of species interaction in the ecology of tick-borne diseases, those being all tick species, pathogens, hosts and other species which might play a role in tick-borne diseases complex ecosystems.
    Parasites & Vectors 06/2013; 6(1):190. · 3.25 Impact Factor
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    ABSTRACT: BACKGROUND: Although Ixodes spp. are the most common ticks in North-Western Europe, recent reports indicated an expanding geographical distribution of Dermacentor reticulatus in Western Europe. Recently, the establishment of a D. reticulatus population in Belgium was described. D. reticulatus is an important vector of canine and equine babesiosis and can transmit several Rickettsia species, Coxiella burnetii and tick-borne encephalitis virus (TBEV), whilst Ixodes spp. are vectors of pathogens causing babesiosis, borreliosis, anaplasmosis, rickettsiosis and TBEV. METHODS: A survey was conducted in 2008-2009 to investigate the presence of different tick species and associated pathogens on dogs and cats in Belgium. Ticks were collected from dogs and cats in 75 veterinary practices, selected by stratified randomization. All collected ticks were morphologically determined and analysed for the presence of Babesia spp., Borrelia spp., Anaplasma phagocytophilum and Rickettsia DNA. RESULTS: In total 2373 ticks were collected from 647 dogs and 506 cats. Ixodes ricinus (76.4%) and I. hexagonus (22.6%) were the predominant species. Rhipicephalus sanguineus (0.3%) and D. reticulatus (0.8%) were found in low numbers on dogs only. All dogs infested with R. sanguineus had a recent travel history, but D. reticulatus were collected from a dog without a history of travelling abroad. Of the collected Ixodes ticks, 19.5% were positive for A. phagocytophilum and 10.1% for Borrelia spp. (B. afzelii, B. garinii, B. burgdorferi s.s., B. lusitaniae, B. valaisiana and B. spielmanii). Rickettsia helvetica was found in 14.1% of Ixodes ticks. All Dermacentor ticks were negative for all the investigated pathogens, but one R. sanguineus tick was positive for Rickettsia massiliae. CONCLUSION: D. reticulatus was confirmed to be present as an indigenous parasite in Belgium. B. lusitaniae and R. helvetica were detected in ticks in Belgium for the first time.
    Parasites & Vectors 06/2013; 6(1):183. · 3.25 Impact Factor
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    ABSTRACT: The cysteine-rich secretory/antigen 5/pathogenesis-related 1 (CAP) protein superfamily is composed of a functionally diverse group of members that are found in both eukaryotes and prokaryotes. The excretome/secretome of numerous helminths (parasitic nematodes) contains abundant amounts of CAP members termed activation-associated secreted proteins (ASPs). Although ASPs are necessary for the parasitic life cycle in the host, the current lack of structural and functional information limits both understanding of their actual role in host-parasite interactions and the development of new routes in controlling parasitic infections and diseases. Alleviating this knowledge gap, a 1.85 Å resolution structure of recombinantly produced Oo-ASP-1 from Ostertagia ostertagi, which is one of the most prevalent gastrointestinal parasites in cattle worldwide, was solved. Overall, Oo-ASP-1 displays the common hallmark architecture shared by all CAP-superfamily members, including the N-terminal CAP and C-terminal cysteine-rich domains, but it also reveals a number of highly peculiar features. In agreement with studies of the natively produced protein, the crystal structure shows that Oo-ASP-1 forms a stable dimer that has been found to be primarily maintained via an intermolecular disulfide bridge, hence the small interaction surface of only 306.8 Å(2). Moreover, unlike any other ASP described to date, an additional intramolecular disulfide bridge links the N- and C-termini of each monomer, thereby yielding a quasi-cyclic molecule. Taken together, the insights presented here form an initial step towards a better understanding of the actual biological role(s) that this ASP plays in host-parasite interactions. The structure is also essential to help to define the key regions of the protein suitable for development of ASP-based vaccines, which would enable the current issues surrounding anthelmintic resistance in the treatment of parasitic infections and diseases to be circumvented.
    Acta Crystallographica Section D Biological Crystallography 04/2013; 69(Pt 4):493-503. · 7.23 Impact Factor
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    ABSTRACT: Ostertagia ostertagi is considered one of the most economically important bovine parasites. As an alternative for anthelmintic treatment, an experimental host-protective vaccine was previously developed based on ASP-proteins derived from the adult worms. Intramuscular injection of this vaccine, combined with QuilA as adjuvant, significantly reduced the faecal egg counts by 59 %. However, the immunological mechanisms triggered by the vaccine are still unclear. Therefore, in this study, the differences in immune responses at the site of infection, i.e. the abomasal mucosa, between ASP/QuilA-vaccinated animals and QuilA-vaccinated control animals were investigated on a transcriptomic level, using a whole genome bovine micro-array, combined with histological analysis. Sixty nine genes were significantly impacted in animals protected by the vaccine, 48 of which were upregulated. A correlation study between the parasitological parameters and gene transcription levels showed that the transcription levels of two of the upregulated genes, granulysin (GNLY) and granzyme B (GZMB) negatively correlated to cumulative faecal egg counts and total worm counts, respectively. Both genes also positively correlated to each other, and to another upregulated gene, the IgE receptor subunit FCER1A. Surprisingly, these three genes also correlated significantly to CMA1, a mast cell marker, and to cell counts for mast cells and cells previously described as globule leukocytes. Furthermore, immunohistochemical data showed that GNLY was present in the granules of globule leukocytes and that it was secreted in the mucus. Overall, the results suggest a potential role of granule exocytosis by globule leucocytes, potentially IgE-mediated, in the vaccine induced protection against O. ostertagi.
    Infection and immunity 03/2013; · 4.16 Impact Factor
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    ABSTRACT: SUMMARY Members of the ATP-binding cassette (ABC) transporter family (P-glycoproteins, Half-transporters and Multidrug Resistant Proteins) potentially play a role in the development of anthelmintic resistance. The aim of this study was to investigate the possible involvement of ABC transporters in anthelmintic resistance in the bovine parasite, Cooperia oncophora. Partial sequences of 15 members of the ABC transporter protein family were identified, by mining a transcriptome dataset combined with a degenerate PCR approach. Reverse transcriptase PCR showed that most of the ABC transporters identified were constitutively transcribed throughout the life cycle of C. oncophora. Constitutive differences in gene transcript levels between a susceptible and resistant isolate were only observed for Con-haf-9 and Con-mrp-1 in eggs of the resistant isolate, while no differences were observed in L3 or the adult life stage. Analysis of resistant adult worms, collected from calves 14 days after treatment with either ivermectin or moxidectin, showed a significant 3- to 5-fold increase in the transcript levels of Con-pgp-11 compared to non-exposed worms. Interestingly, a 4-fold transcriptional up-regulation of Con-pgp-11 was also observed in L3 of the resistant isolate, after in vitro exposure to different concentrations of ivermectin, whereas this effect was not observed in exposed L3 of the susceptible isolate. The results suggest that the worms of this particular resistant isolate have acquired the ability to up-regulate Con-pgp-11 upon exposure to macrocyclic lactones. Further work is needed to understand the genetic basis underpinning this process and the functional role of PGP-11.
    Parasitology 01/2013; · 2.36 Impact Factor
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    ABSTRACT: Despite Giardia duodenalis being one of the most commonly found intestinal pathogens in humans and animals, little is known about the host-parasite interactions in its natural hosts. Therefore, the objective of this study was to investigate the intestinal response in calves following a G. duodenalis infection, using a bovine high-density oligo microarray to analyze global gene expression in the small intestine. The resulting microarray data suggested a decrease in inflammation, immune response, and immune cell migration in infected animals. These findings were examined in more detail by histological analyses combined with quantitative real-time PCR on a panel of cytokines. The transcription levels of IL-6, IL-8, IL-13, IL-17, and IFN-γ showed a trend of being downregulated in the jejunum of infected animals compared to the negative controls. No immune cell recruitment could be seen after infection, and no intestinal pathologies, such as villus shortening or increased levels of apoptosis. Possible regulators of this intestinal response are the nuclear peroxisome proliferator-activated receptors alpha (PPARα), and gamma (PPARγ) and the enzyme adenosine deaminase (ADA), all for which an upregulated expression was found in the microarray and qRT-PCR analyses.
    PLoS ONE 07/2012; 7(7):e40985. · 3.53 Impact Factor
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    ABSTRACT: The present study aimed to obtain data on the occurrence of Giardia duodenalis in calves in four major cattle rearing countries in Europe (Germany, UK, France and Italy), along with genotyping data and risk factors associated with these infections. A total of 2072 calves were sampled on 207 farms. The majority of the animals were Holstein dairy or mixed Holstein calves (n=1565 or 75.5%), and were female (n=1640 or 79.1%). The average age was 7.8 weeks (SD=4.1; median=7; range=2-16 weeks). All fecal samples were tested using a commercially available monoclonal antibody-based ELISA. The overall apparent prevalence of G. duodenalis for the four countries was 45.4% (n=942/2072) and the overall farm prevalence was 89.9% (186/207), with differences in both animal and farm prevalence between the four countries. The prevalence was significantly higher in animals up to 8 weeks (OR=1.88; P<0.001) compared to older calves, and several management factors including contact with the Dam, Frequency of cleaning of the Maternity Pens, and Disinfection of the Calf Housing were found to be associated with infection. Positive samples were withheld for genotyping using the β-giardin and triose phosphate isomerase gene: G. duodenalis assemblage E was most prevalent, although 43% of the isolates were typed as assemblage A, with differences in between countries. Furthermore, 32% of the examined samples was found to be a mixed assemblage A and E infection, which is consistent with previous reports. The results of the present study confirm previous findings in other European countries that G. duodenalis infections are common in calves. The infection especially occurs in animals younger than 2 months, and the proportion of positive animals gradually decreased with increasing age.
    Veterinary Parasitology 07/2012; · 2.55 Impact Factor

Publication Stats

2k Citations
351.16 Total Impact Points

Institutions

  • 1994–2014
    • Ghent University
      • • Faculty of Veterinary Medicine
      • • Department of Virology, Parasitology and Immunology
      Gand, Flanders, Belgium
  • 2013
    • University of Liège
      • Unit of Epidemiology and Applied Veterinary Risk Analysis
      Luik, Walloon Region, Belgium
    • Norwegian School of Veterinary Science
      • Department of Food Safety and Infection Biology
      Kristiania (historical), Oslo County, Norway
  • 2007
    • University of Zambia
      • School of Veterinary Medicine
      Lusaka, Lusaka Province, Zambia
  • 2003
    • Institut Pasteur de Lille
      Lille, Nord-Pas-de-Calais, France