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Biomedical subjects

J Vercruysse

Publications and source records attributed to J Vercruysse.

At least 37 records · Page 2Linked to original sources
PubMed2005

The efficacy of an oral treatment with paromomycin against an experimental infection with Giardia in calves.

A controlled and blinded study was conducted to evaluate the efficacy and safety of a treatment with paromomycin sulphate against an experimental Giardia infection in calves. Animals were infected with 10(5)Giardia cysts of cattle origin and were either treated 11 days later with 25, 50 or 75 mg paromomycin/(kg body weight per day) during 5 consecutive days or not treated (control group). Efficacy was evaluated based on reduction in cyst excretion. Furthermore weight gain and diarrhea scores were monitored. In the group treated with 75 mg/kg per day there was a 100% reduction in cyst excretion until 9 days after the start of the treatment (D9) and a very high reduction (> or =98%) until D13. There was a high reduction (> or =93%) until D9 and D13 in the groups treated with 25 and 50 mg/kg, respectively. The cumulative cyst excretion on D13 was significantly (P<0.05) lower in the groups treated with 75 and 50 mg/kg compared to the control group. Although there was a trend towards higher weight gain and less diarrhea in the treated groups, differences between groups were not significant. No adverse reactions to the paromomycin treatment were recorded. Furthermore, the need for reliable parameters for evaluation of treatments against protozoal infections is emphasised.

Administration, Oral↗
PubMed2005

The influence of colostrum on infection of calves around 7 months of age with Schistosoma mattheei.

Studies have indicated that the intake of colostrum could modulate the offspring reaction towards early schistosome infections. The effect of colostrum (containing immunoglobulins, parasite antigens, immune cells and other cell-related products) on late Schistosoma infections is to our knowledge not documented. The objective of the present study is to determine whether the intake of colostrum from Schistosoma mattheei infected cows will modify late S. mattheei infection patterns in their offspring. Six calves born to confirmed non-infected cows and 10 calves born to confirmed infected mothers were purchased after intake of colostrum. All calves were exposed to a total experimental challenge of 2500 cercariae around the age of 7 months. Serum samples were collected before and after intake of colostrum and monthly thereafter for the determination of specific antibody levels. Faecal samples were collected monthly from 42 days after infection for the determination of faecal egg counts. Six calves of each group were slaughtered around the age of 15 months for worm recovery and tissue egg counting. No differences between both groups were observed in immunoglobulin levels and faecal egg counts after infection, and in worm counts and tissue egg counts at necropsy. In conclusion colostral effects, which were noticed at an early age, are no longer present around the age of 7 months. As such calves which are born during a season of high Schistosoma transmission will still be under colostral influence and therefore be more protected against a primary challenge than calves born during a low transmission season, as the latter will only receive their first challenge when colostral protective effects have disappeared.

Aging↗
PubMed2005

Placental transfer of immunoglobulins in cattle infected with Schistosoma mattheei.

Although the epitheliochorial placenta of ruminants does not allow passage of immunoglobulins from dam to foetus specific antibodies have been detected at birth in calves born to Schistosoma mattheei-infected cows. The present study determined the prevalence of calves born with specific antibodies for S. mattheei and the origin of these antibodies. For the determination of the prevalence, 100 calves born to infected mothers in an endemic area (Zambia) were examined, 24 were seropositive. To study the origin of these antibodies placentomes of 40 naturally S. mattheei-infected cows were examined for the presence of schistosome eggs and lesions which could explain foetal priming and/or leakage of maternal antibodies and/or antigen into the foetus. Tissue damage and schistosome eggs were observed on the maternal as well as the foetal side of the placentomes. In order to determine the specific nature of the antibody response, antibody profiles against soluble adult worm antigen preparation (SWAP) of S. mattheei were compared by Western blot between dams and their newborn calves (n = 8). The specific recognition profiles were identical for the seropositive calves and their dams on SWAP mattheei. Identical recognition profiles between dams and calves were also observed when sera were analysed on Escherichia coli, a pathogen of which the foetus should be free, and would indicate passive antibody transfer from the dam. In conclusion, the present study shows that S. mattheei could induce placentome lesions and that eggs can cross the placenta. Consequently, foeti can come into contact with S. mattheei antigens in utero, and might also contain maternal antibodies from leakage through placentome lesions. As such, the infection status of the mother could have far reaching effects on the immunological status of her offspring and modify their reaction upon infection.

Animals↗
PubMed2005

Protection studies with a globin-enriched protein fraction of Ostertagia ostertagi.

The protective capacity of an adult stage Ostertagia ostertagi globin antigen was tested in four vaccination experiments in cattle. In a preliminary experiment, calves were vaccinated three times intraperitoneally with 250 microg globin in Freund's adjuvant and challenged with a trickled infection of 25,000 infective larvae. In three subsequent field studies, calves were vaccinated twice or three times intramuscularly with 80-100 microg globin in Quil A and challenged with a natural gastrointestinal nematode infection on pasture. Higher globin-specific antibody levels were detected in the vaccinated calves than in the control animals in all vaccine trials. In the preliminary experiment, geometric mean cumulative egg counts in the globin group were reduced by 52% and total worm burdens were reduced by 28%, compared to the controls. In the first field trial cumulative faecal egg counts were reduced by 63% in the vaccinated calves. However, the reduction in faecal egg output in these two experiments was not statistically significant and no reduction in faecal egg counts was observed in the vaccinated animals in the two last field trials. In conclusion, vaccination of calves with O. ostertagi globin resulted in highly variable protection levels after challenge infection.

Adjuvants, Immunologic↗
PubMed2005

Evaluation of diagnostic tests for Trypanosoma evansi in experimentally infected pigs and subsequent use in field surveys in north Vietnam and Thailand.

This study is concerned with the evaluation of established diagnostic tests for diagnosis of Trypanosoma evansi in pigs. The immune trypanolysis test (TL), card agglutination test (CATT), latex agglutination test (LATEX), enzyme-linked immunosorbent assay (ELISA), microhaematocrit centrifugation technique (MHCT) and mouse inoculation (MI) tests were initially evaluated in experimentally infected fattening pigs. All infected pigs were confirmed parasitologically positive with both MHCT and MI. Results of the serological assays indicated that the TL could be a reference test for the presence of RoTat 1.2 antibodies in pigs. The results of the CATT and LATEX were inconsistent with the TL while the ELISA results correlated with the TL results. The four serological assays were subsequently used in two field surveys in Vietnam and Thailand. Results of the two agglutination assays (CATT and LATEX) were not consistent and did not correlate with TL results. The ELISA at percentage positivity of 22 appeared to have good ability to discriminate between seropositive and seronegative animals. Of the 437 samples collected at smallholder pig premises in northern Vietnam, no positive pigs were detected with the TL test. In Thailand, 77 samples were collected from five farrowing farms with a history of surra. Two parasitologically positive sows were found and on each farm seropositive sows were detected.

Agglutination Tests↗
PubMed2005

Molecular analysis of astacin-like metalloproteases of Ostertagia ostertagi.

In this study, we describe the molecular analysis of zinc-metalloproteases from the abomasal nematode Ostertagia ostertagi which were exclusively recognized by local antibodies of immune cattle. Full-length or partial coding sequences of 4 different zinc-metalloprotease cDNAs of Ostertagia (met-1, -2, -3 and -4) were amplified using gene-specific primers using the 3'- and 5'-Rapid Amplification of cDNA Ends (RACE) technique. Sequence analysis identified the cDNAs as encoding zinc-metalloproteases, which showed between 62% and 70% homology to a metalloprotease 1 precursor of Ancylostoma caninum. The full-length cDNA of met-1 consists of an open reading frame (ORF) of 586 amino acids which contains 5 potential N-glycosylation sites and a predicted zinc-binding domain (HEBXHXBGFXHEXXRXDRD). The complete coding sequence of met-3 contains an ORF of 508 aa and the same conserved zinc-binding domain. These domains are signature sequences of the astacin family of the superfamily of metzincin metalloproteases. The presence of a threonine amino acid after the third histidine in MET-1 and MET-3, however, may place them in a new family or subfamily. Real-time PCR analysis of L3, exsheathed L3, L4 and adult cDNA identified transcription of the 4 metalloproteases in different life-stages. The protein MET-1 was expressed in insect cells using the baculovirus expression system but the immunization of calves with this molecule did not lead to protection against challenge infection.

Amino Acid Sequence↗
PubMed2005

Cytokine responses in immunized and non-immunized calves after Ostertagia ostertagi infection.

The objective of this study was to evaluate abomasal cytokine responses in helminth-naive calves and calves vaccinated with protective antigen fractions from Ostertagia ostertagi after an experimental challenge infection with infective third stage (L3) larvae. Abomasal lymph nodes and/or abomasal mucosa were collected and messenger RNA for the Th1 cytokines (IFN-gamma, IL-2, IL-12 p40 subunit), the Th2 cytokines (IL-4, IL-5, IL-6, IL-10, IL-13, IL-15) and the Th3/Tr cytokine TGF-beta was quantified by real-time RT-PCR. Vaccination had no effect on cytokine profiles in either the abomasal lymph nodes or the abomasal mucosa. However, following infection all calves showed a significant decrease in the Th1 cytokines, IFN-gamma and IL-12 p40, and a significant increase in the Th2 cytokines, IL-4, IL-5, IL-10 and IL-13 in the lymph nodes, compared to non-infected calves. No correlation between the Th2 response and protection induced by vaccination could be demonstrated. In contrast, a Th2 pattern was not observed in the mucosa of the infected calves, which exhibited an increase in IFN-gamma as well as in the Th2 cytokines IL-4, IL-5 and IL-10 mRNA. No significant association was observed in the abomasal mucosa between any examined cytokine mRNA level and immune effector responses such as parasite-specific antibodies or the number of mucosal mast cells or eosinophils.

Abomasum↗
PubMed2004

Evaluation of the indirect fluorescent antibody test as a diagnostic tool for East Coast fever in eastern Zambia.

Serological surveys using the schizont indirect fluorescence antibody test (IFAt) are routinely carried out to monitor the Theileria parva infection prevalence. The present study evaluates the diagnostic accuracy of the IFAt in eastern Zambia, where the transmission of T. parva is highly seasonal. The data set resulted from a sentinel herd (n = 105 animals) study carried out between 1995 and 2000 and was split into an epidemic period, during which the majority of the cattle became infected, and an endemic period with seasonal disease incidence in calves. In the epidemic period the T. parva seroprevalence followed closely the build up of the herd immunity. In the endemic period the seroprevalence fluctuates considerably although most of the animals had been infected. Overall, the diagnostic sensitivity of the IFA test was 55% at cut-off titre 1:40 and 28% at cut-off 1:160. The specificity of the test was 86 and 95%, respectively. A logistic regression model demonstrates that the sensitivity is significantly lower when the T. parva transmission is low (p < 0.01). The analysis of receiver operator characteristic curves classifies the test as moderately accurate (area under the curve, AUC = 0.79) during the epidemic period and less accurate in the endemic period (AUC = 0.63). Neonatal serology surveys yield a better estimate of the infection prevalence. The sensitivity of the neonatal test was 73% at cut-off titre 1:40 and 24% at cut-off 1:160.

Animals↗
PubMed2004

Evaluation of the chemoprophylactic efficacy of 10% long acting injectable moxidectin against gastrointestinal nematode infections in calves in Belgium.

The chemoprophylactic efficacy of a single dose of the 10% long acting (LA) injectable formulation of moxidectin on nematode infections in calves, was evaluated. Two similar groups of 11 female, first grazing season Holstein calves were turned out in early May on separate plots of a single, naturally infected pasture. Until 56 days post-treatment (pt), the percentage reduction in faecal egg output was 100%, remaining above 90% during the entire trial, except for day 126 pt. More than 90% of the larvae in the treated group were identified as Cooperia until 140 days after treatment and more than 70% during the rest of the trial, whereas in the control group Cooperia was the most abundant species until day 84 pt and Ostertagia from 126 days pt onwards. The reduction in faecal egg output in the treated group was reflected in the mean pepsinogen levels being below the pathogenic threshold at the end of the grazing season (1.8 units of tysrosine (U tyr)) and the absence of diarrhoea during the second half of the grazing season. In the control group pepsinogen levels remained high (mean: 5.5 U tyr) and prolonged diarrhoea occurred in the second half of the grazing season. Furthermore, the weight gain for the treated group at the end of the grazing season was 41.9 kg higher than for the control group. At necropsy, the reduction in O. ostertagi worm burden in the treated group was 97.5% compared to the control group, while the reduction in C. oncophora worm burden was 57%. An additional benefit of the long acting parasitological control, was reduced pasture contamination.

Animals↗
PubMed2004

Variations in the immune response to natural Schistosoma mattheei infections in calves born to infected mothers.

During previous work Schistosoma antibodies and circulating antigens were detected at birth in the serum from some calves born to Schistosoma mattheei infected mothers. The objectives of the present survey were: (1) to investigate the proportion of calves, born to cows infected with S. mattheei, which have specific antibodies and circulating schistosome antigens present in their serum at birth and (2) to investigate whether the presence or absence of these specific antibodies and/or circulating antigens at birth may affect the pattern of a natural S. mattheei infection in calves from 4 to 5 months of age, when the colostral antibodies are thought to be of negligible importance. A total of 28 calves born to infected mothers were randomly selected. Faeces, serum and colostrum samples were collected from the cows at calving, serum samples were collected from the calves at birth (day 0), after intake of colostrum (day 1) and monthly thereafter up to the age of 10 months. Both serum and colostrum samples were analysed for IgG(H+L) against SWAP mattheei and schistosome circulating anodic antigen (CAA) levels. The calves were exposed to a natural challenge from the age of 4-5 months. Faecal samples were collected from the calves monthly, starting at an age of 5 months up to 10 months, and were examined for faecal egg counts. Nine (group 1) out of the 28 calves were found to have specific antibodies in their serum at birth, in 5 of them CAA levels were also detected. In the other 19 calves (group 2) no IgG(H+L) or CAA were detected. At the end of the study faecal egg counts and CAA levels were significantly lower in calves from group 1 compared to group 2. Results confirm earlier work that specific antibodies and circulating antigens may be present in serum from calves at birth, and show that these calves have lower faecal egg counts and CAA levels after exposure to a natural challenge.

Animals↗
PubMed2004

A Bayesian approach for estimating values for prevalence and diagnostic test characteristics of porcine cysticercosis.

Several diagnostic techniques are used to estimate the prevalence of the zoonotic tapeworm Taenia solium in pigs, but none of these tests are perfect, making interpretation of results difficult. A Bayesian approach was used to estimate values for the prevalence and diagnostic test characteristic of porcine cysticercosis by combining results of four imperfect tests. Village pigs (N = 868) slaughtered in Lusaka (Zambia), were bled, and tongue and routine meat inspected; and serum antibody and parasite antigen concentrations were determined by ELISA. A model, based on a multinomial distribution and including all possible interactions between the individual tests required 31 parameters to be estimated, but actually allowed only 15 parameters (i.e. had 15 degrees of freedom) to be estimated. Therefore, prior expert opinion on specificity and (in)-dependence of the tests was entered in the model, resulting in a reduction of the number of parameters to be estimated. The estimated prevalence of porcine cysticercosis was 0.642 (95% confidence interval 0.54-0.91). The performances of the tests were (sensitivity (se)-specificity (sp)): tongue inspection (se 0.210-sp 1.000), meat inspection (se 0.221-sp 1.000), Ab-ELISA (se 0.358-sp 0.917), Ag-ELISA (se 0.867-sp 0.947). To validate the estimates obtained from the model we performed a second study: 65 randomly purchased Zambian village pigs were bled for serum antibody and antigen determination, their tongue and meat inspected; and in addition, the carcasses were dissected for total cysticercus counts (gold standard). Cysticerci were found in 31 pigs (prevalence 0.477, 95% confidence interval 0.35-0.60), overlapping with the estimated prevalence in the first study. Sensitivity and specificity values obtained for the aforementioned tests in this study were in agreement with those estimated. A Bayesian analysis framework offers the possibility to combine prior opinion with experimental data to more accurately estimate the real prevalence of porcine cysticercosis in the absence of a gold standard.

Animals↗
PubMed2004

Estimation of diagnostic test characteristics and prevalence of Giardia duodenalis in dairy calves in Belgium using a Bayesian approach.

A Bayesian approach was used to determine both the test properties of three diagnostic test procedures and the prevalence of Giardia duodenalis in dairy calves in Belgium. A cross-sectional survey was conducted in the province of East Flanders, Belgium. Between September 2001 and December 2003, a total of 100 farms were visited and faecal samples were obtained rectally from 499 calves aged from newborn to 70 days. Because there is no gold standard for the diagnosis of a G. duodenalis infection in dairy calves, a subset of 235 samples obtained on the first 50 farms, was examined using three different assays: microscopical examination, an immunofluorescence assay (IFA) and an antigen detecting Elisa (ELISA). Based on the results of these three tests, Bayesian analysis indicated that the prevalence of G. duodenalis in dairy calves was 0.19 (95% Confidence Interval: 0.11-0.28) and that ELISA (Sensitivity (Se) 0.89 and Specificity (Sp): 0.90) and IFA (Se: 0.77 and Sp: 0.95) were both sensitive and specific diagnostic techniques, whereas microscopical examination was less sensitive (Se: 0.56 and Sp: 0.87). The proportion of positive farms was estimated as 0.42 (0.24-0.62). The prevalence and the cyst excretion in calves from different age categories were based on data obtained by IFA on all 499 samples. The prevalence was highest among four to five week old calves and remained high among older calves up to 10 weeks, but was lower among calves before the age of two weeks. The number of excreted cysts was estimated by IFA and ranged from 100 to 1,040,000 cysts per gram faeces, with a mean of 3516 cysts per gram faeces. The intensity of excretion peaked among four-week-old calves and remained high among calves up to the age of eight weeks. This is the first known study to use Bayesian analysis to estimate the prevalence of G. duodenalis in the faeces of dairy calves and to estimate test characteristics of diagnostic assays used for the detection of G. duodenalis.

Animals↗
PubMed2004

Are the cellular immune responses of children and adults with Schistosoma mansoni infection intrinsically different? Cytokines produced ex vivo in response to antigens and mitogens.

In recently exposed communities, intensity of schistosomiasis infection increases as children age and then drops again in adulthood, indicating that host maturity is an important aspect of resistance to schistosomiasis. We investigated whether the cellular immune response to the parasite was correlated with age in subjects with similar daily patterns of exposure, current intensities of infection and number of years of exposure. The cellular immune response of subjects with either 'low' (under 200 eggs per gram (EPG)) or 'high' (over 400 EPG) intensities of infection was investigated, in a recently established focus where subjects had similar histories of exposure and number of years of experience with Schistosoma mansoni. Subject's whole blood was cultured with adult worm antigen (AWA), a mixture of phytohaemagglutinin (PHA) and lipopolysaccharide (LPS), or left unstimulated, and culture supernatants were tested for IL-4, IL-5, IL-10 and IFN-gamma. Children and adults tended to respond differently to schistosome antigen. The most statistically significant illustration of this was the negative correlation between age and IL-5 produced by samples from people with low intensities of infection cultured with AWA (P < 0.003, P < 0.05 after Bonferroni correction). IL-10 produced by samples cultured with PHA and LPS was also notably lower in children than in adults, although not formally significant after Bonferroni correction. This indicates that it is possible for age, independently of intensity of infection or experience with the parasite, to influence the immune response to schistosomiasis.

Adolescent↗
PubMed2004

Validation of the protective Ostertagia ostertagi ES-thiol antigens with different adjuvantia.

Intramuscular immunization of calves with an excretory-secretory antigen fraction enriched for cysteine proteinase activity (ES-thiol) and QuilA as adjuvant induces a protective immune response against the abomasal nematode Ostertagia ostertagi. The objectives of the present study were to confirm the protective capacity of ES-thiol in combination with QuilA, to test Al(OH)(3) as adjuvant for vaccination against O. ostertagi and to look for correlations between protection and immunological effector responses. Calves(seven animals/group) were vaccinated three times intramuscularly with 100 micro g antigen and/or adjuvant (ES-thiol with QuilA, ES-thiol with Al(OH)(3), QuilA alone and Al(OH)(3) alone) and subsequently challenged with a trickled oral infection of 25 000 infective larvae in total over 25 days. Faecal egg counts in the ES-thiol QuilA group were reduced by 56% during the two-month period of the trial compared to the QuilA control group (P < 0.002). Calves immunized with ES-thiol QuilA had significantly smaller adult worms (P < 0.002) and less eggs/female worm (P < 0.05) compared to the QuilA control group. No differences in egg output, worm counts or parameters of worm fitness were observed in the ES-thiol Al(OH)(3) group compared to the Al(OH)(3) control group. Although the protective immune mechanism against O. ostertagi remains unknown, protection in the ES-thiol QuilA group was associated with high levels of parasite-specific antibodies in the abomasal mucosa.

Abomasum↗
PubMed2004

[Bulinus truncatus, intermediate host of Schistosoma haematobium in the Senegal River Basin (SRB)].

To assess the role of Bulinus truncatus in the transmission of urinary schistosomiasis in the Senegal River Basin (SRB), the relations between B. truncatus and Schistosoma haematobium were studied. The compatibility study shows that B. truncatus is susceptible to infection with S. haematobium in the Upper Valley of the SRB. The malacological follow up reveals the presence of B. truncatus naturally infected with schistosomes cercariae in the Middle Valley. The identification of these schistosomes as S. haematobium by the Single Strand Conformational Polymorphism technique (SSCP) confirms the participation of B. truncatus in the dynamic transmission.

Animals↗
PubMed2003

World Association for the Advancement of Veterinary Parasitology (WAAVP) guidelines for evaluating the effectiveness of anthelmintics in chickens and turkeys.

These guidelines have been prepared to assist in the planning, operation and interpretation of studies designed to assess the effectiveness of drugs against helminth parasites of chickens and turkeys. They are the first to be compiled under the auspices of the World Association for the Advancement of Veterinary Parasitology (WAAVP) for these parasites. The advantages and disadvantages of the widely used critical and controlled tests are discussed. Information is provided on the selection of animals for experiments, animal housing, feed, dose determination studies, confirmatory and field trials, record keeping and necropsy procedures. This document should help investigators and those involved in product approval and registration in conducting and evaluating studies concerned with determining the effectiveness and safety of anthelmintic drugs.

Animal Husbandry↗