Publications

anthelmintic resistance.	in populations of livestock in which anthelmintics have become the only means of control, individual worms in some species of helminths evade the effects of specific anthelmintics. if these resistant individuals are selected (by removing the susceptible individuals in the population) then the resistant worm population on individual farms becomes dominant in both numbers and effect. this selection of anthelmintic resistant populations is most often reported in equids and small ruminants (the host ...	1993	8484205
pathophysiology of infection with ostertagia ostertagi in cattle.	infection with the abomasal nematode, ostertagia ostertagi, is an important cause of impaired productivity in young cattle in temperate parts of the world. such losses have been associated with marked changes in feed intake, gastrointestinal function, protein, energy and mineral metabolism, and in body composition. the reduction in feed intake is an important factor in the pathogenesis of infection and may account for a large part of the difference in weight gain between ad libitum fed control a ...	1993	8484207
evaluation of pepsinogen, gastrin and antibody response in diagnosing ostertagiasis.	ostertagia ostertagi is widely distributed and is one of the most important parasites affecting young bovine livestock. there is, therefore, a substantial need for sensitive and specific parameters in support of diagnosis of ostertagiasis, especially for subclinical disease related to production losses. in this review, the value and application of pepsinogen, gastrin and antibody response as diagnostic tools are discussed. these three parameters are useful and comparable for confirming clinical ...	1993	8484209
gastrointestinal nematode infections and weight gain in dairy replacement stock: first-year calves.	for the evaluation of control strategies against, and economic impact of gastrointestinal nematode infection, the quantitative relationship between level of exposure to infection and growth performance is important. available data in the literature are summarised. based on questions derived from earlier work concerning the relationships between infection, growth performance and acquired immunity during the entire rearing period, two experiments were set up. in these experiments, groups of calves ...	1993	8484213
mathematical models for the population biology of ostertagia ostertagi and the significance of aggregated parasite distributions.	parasite frequency distributions are frequently aggregated. such distributions are conveniently described using the negative binomial frequency distribution. this distribution is completely characterized by two parameters: the mean of the distribution and an exponent, k. the degree of aggregation is inversely proportional to the value of k. aggregated parasite distributions enhance the ability of regulatory processes to maintain parasite populations at or near their equilibrium level but incorpo ...	1993	8484215
ostertagiasis in the cow and weaned calf in the northeastern usa.	most gastrointestinal nematode infections of cattle in the northeast usa are combinations of ostertagia ostertagi and cooperia oncophora. these infections are usually of little consequence in adult cattle because of immunity and consequent low levels of infection. some work has been done on the effects of infection on milk production but the results are equivocal. clinical ostertagiasis in calves can lead to mortality. such outbreaks are often associated with situations where calves are pastured ...	1993	8484217
epidemiology of ostertagia ostertagi in cow-calf herds in the southeastern usa.	ostertagia ostertagi is commonly found in the brood cow and nursing calf in the southeastern usa, this information being derived from fecal egg counts, coproculture and necropsy results; however, clinical disease and large burdens of this parasite are rarely reported. fecal egg counts in brood cows are routinely low and are generally reported to be 10 eggs per gram of feces (epg) or less. nematode egg counts in spring-born calves are also generally low prior to weaning; they increase steadily du ...	1993	8484218
epizootiology of ostertagia ostertagi in cow-calf production systems in the american midwest.	the most common gastrointestinal nematodes found in cattle in the midwest are ostertagia ostertagi and cooperia oncophora. other parasites include haemonchus placei, bunostomum phlebotomum and nematodirus helvetianus. parasite numbers are generally low in this region, as indicated by fecal egg counts and tracer calf worm recoveries, and the numbers of parasites decrease as one travels farther north. this decrease in parasite numbers also corresponds to a similar reduction in the prevalence of cl ...	1993	8484220
current and future prospects for control of ostertagiasis in northern europe--examples from denmark.	this review primarily discusses the status and prospects for control of bovine ostertagiasis in northern europe, with examples from denmark. there are different ongoing developments in agricultural systems and practices, and methods and possibilities for practical control depend on the intensity and specialisation of these; the modern dairy farm remains at highest risk of parasitism, owing to increasing stocking densities and limited natural control elements at hand. epidemiology and course of i ...	1993	8484221
epidemiology of ostertagia ostertagi in weaner-yearling cattle.	epidemiologic events in the life cycle of ostertagia ostertagi are best known in the weaner-yearling phase of cattle development throughout the concentrated cattle-rising areas of the world. animal and pasture management demands placed on this age class are greater than for suckling calves and adult stock in either beef or dairy breeds. this fact alone would likely account for a higher prevalence of clinical and subclinical disease in weaner-yearlings. additionally, the developing immune respons ...	1993	8484223
the systematics of nematodes that cause ostertagiasis in domestic and wild ruminants in north america: an update and a key to species.	studies of medium stomach worms (subfamily ostertagiinae) of domestic and wild ruminants in north america have refined our understanding of the systematics, host distribution and biogeography of these nematodes. strong support for recognition of monophyly for the ostertagiinae has resulted from preliminary phylogenetic analyses of morphological characters among these and other trichostrongylids. evaluation of morphological and biochemical characters in our laboratory and elsewhere has not refute ...	1993	8484224
regulation of immunity to ostertagia ostertagi.	knowledge of bovine immune response to ostertagiasis is important to understanding the mechanisms of innate and acquired immunity to this economically important helminth parasite that infects cattle worldwide. infection causes both antibody and cellular immune responses. evidence shows that ostertagia possesses excretory-secretory (es) molecules that may regulate immune cell responses that affect acquired immunity and pathophysiological changes to infection. ostertagia can down-regulate antibody ...	1993	8484225
influence of host genetics upon antibody responses against gastrointestinal nematode infections in cattle.	previous studies have shown that the number of gastrointestinal nematode eggs released per gram of feces (epg) of calves is strongly influenced by host genetics. the purpose of this study was to determine if host genetics also influenced immune recognition of parasite antigens in these same calves. serum samples were taken at monthly intervals from calves during their first grazing season, from approximately 4 months after the onset of calving and were continued until weaning. serum samples were ...	1993	8484226
inverse relationship between ige and worm burdens in cattle infected with ostertagia ostertagi.	changes in serum total and ostertagia-specific ige levels, and pepsinogen concentrations were evaluated in 28 holstein calves naturally or experimentally infected with ostertagia ostertagi. in addition, ige and pepsinogen concentrations were determined in abomasal lymph. results showed that (1) lymph ige responses were inversely correlated with worm burdens, and (2) serum ige levels were unreliable for predicting worm burdens.	1993	8493771
biological control of ostertagia ostertagi by feeding selected nematode-trapping fungi to calves.	three nematode-trapping fungi, one arthrobotrys oligospora and two duddingtonia flagrans isolates, were fed to ostertagia ostertagi-infected calves to test their ability to destroy larvae of this parasite in faeces and consequently to reduce the transmission of infective larvae to herbage. the fungi had previously been selected for their capability to pass the alimentary tract of cattle without losing growth and nematode-trapping potentials. dung was collected from three calves each fed one of t ...	1993	8509616
genetic structure of populations of ostertagia ostertagi.	most genetic work to distinguish strains of parasitic helminths focuses on searching for genetic markers to correlate with phenotypes of interest, but in this study genetic diversity among individual ostertagia ostertagi adults is partitioned into components within and between populations. restriction fragment polymorphism data on mitochondrial dna from ten individual worms from each of five different parasite populations are analyzed. three of these populations are characterized by arrested lar ...	1993	8097898
abomasal lymphatic lymphocyte subpopulations in cattle infected with ostertagia ostertagi and cooperia sp.	abomasal lymphatic cannulation was performed on steers naturally or experimentally infected with ostertagia ostertagi and cooperia sp.. abomasal lymphatic lymphocyte subpopulations were evaluated using antibodies specific for bovine mononuclear cell surface antigens, followed by flow cytometric analysis. when compared with the non-infected or experimentally infected steers, naturally infected steers with type 1 or type 2 ostertagiosis had increased percentages of b-lymphocytes. the percentages o ...	1993	8116222
prevention of pathophysiologic and immunomodulatory effects of gastrointestinal nematodiasis in calves by use of strategic anthelmintic treatments.	effects of strategic anthelmintic treatment on pathophysiologic and immunomologic changes induced by infection with ostertagia ostertagi and cooperia oncophora were studied in 2 groups, of 12 calves each: an infected group, inoculated with 200,000 mixed o ostertagi and c oncophora third-stage larvae (l3) on day 1; and an infected-treated group, similarly inoculated, but treated with ivermectin at 9 and 33 days. all calves were also inoculated at 12 weeks with brucella abortus vaccine, at 13 week ...	1993	8116936
partial characterization of proteolytic enzymes in different developmental stages of ostertagia ostertagi.	proteolytic enzymes present in extracts of third (l3) and fourth (l4) stage larvae and adults of the cattle nematode ostertagia ostertagi were defined on the basis of ph optima and proteinase inhibitor sensitivity in spectrophotometric assays using azocasein and elastin-orcein as protein substrates. evidence that different classes of proteinases are expressed in a stage specific manner was provided by the contrasting ph optima and inhibitor sensitivities shown by the enzymes in the different par ...	1993	8132971
abomasal interstitial fluid-to-blood concentration gradient of pepsinogen in calves with type-1 and type-2 ostertagiosis.	pepsinogen and protein concentrations were determined in blood samples, collected from the left gastroepiploic artery and vein, and in abomasal lymph from 15 steers naturally infected with ostertagia ostertagi and 4 uninfected steers. in steers with type-1 ostertagiosis, the concentration gradient between the mucosal interstitium and the blood alone could account for higher than normal serum pepsinogen concentrations. high interstitial pepsinogen concentrations may have resulted from increased e ...	1993	8214898
characterisation of ostertagia ostertagi antigens by the different bovine immunoglobulin isotypes.	antigenic differences between the developmental stages of ostertagia ostertagi were studied by sds-page and western blotting. gel electrophoresis showed a complex protein pattern different for every stage with the o ostertagi fourth stage larvae (l4) showing an intermediate protein pattern between the third stage larvae (l3) and the adult stage. immunoblotting showed that igg1, igg2 and igm immunoglobulins present in serum from uninfected calves identified several o ostertagi antigens at every s ...	1993	8235088
activity of doramectin against nematode endoparasites of cattle.	a series of 28 controlled anthelmintic studies, involving 634 cattle, was conducted throughout north america and europe to evaluate the efficacy of doramectin against a broad range of gastrointestinal parasitic nematode species and lungworms in naturally and experimentally infected animals. within each study, one or two groups were treated with doramectin at 200 micrograms kg-1 and another group received no drug treatment. worm burdens were estimated by standardised techniques, and efficacy asse ...	1993	8236735
efficacy of doramectin against field nematode infections of cattle in latin america.	two studies were conducted, one in argentina and one in brazil, to evaluate the therapeutic efficacy of doramectin administered subcutaneously at a dose rate of 200 micrograms kg-1 (1 ml per 50 kg) to cattle harboring mixed field infections of gastrointestinal nematodes. in each trial, 20 heifers were randomly allocated to a control or treated group of ten animals each, on the basis of fecal egg counts. animals in the treated and control groups received an injection of doramectin or saline in th ...	1993	8236736
persistent efficacy of doramectin against experimental nematode infections in calves.	three studies were conducted involving cattle exposed to experimental nematode infections. these studies were designed to investigate the prophylactic activity of a single subcutaneous treatment of doramectin at 200 micrograms kg-1 body weight against infections of ostertagia ostertagi, cooperia oncophora and dictyocaulus viviparus. for each study, parasite-naive calves were randomly allocated to either a treated or a matched control group. one group received doramectin and the other received do ...	1993	8236737
doramectin--a potent novel endectocide.	doramectin, 25-cyclohexyl-5-o-demethyl-25-de(l-methylpropyl)avermectin a1a, was selected as the best of a series of novel avermectins prepared by mutational biosynthesis. the primary evaluation of its in vivo antiparasitic activity was carried out using a rat trichostrongylus colubriformis model and a rabbit psoroptes cuniculi model. in each case the new avermectin performed favourably relative to dihydroavermectin b1a (dhavm), the major component of ivermectin. doramectin was extensively evalua ...	1993	8236738
efficacy of doramectin in the prevention of gastrointestinal nematode infections in grazing cattle.	two studies were performed to investigate the efficacy of doramectin in the prevention of infection with ostertagia ostertagi and cooperia oncophora in grazing calves. in each study, 24 parasite-naive calves were randomly allotted to two equal groups and treated with either doramectin at 200 micrograms kg-1 or saline prior to mid-season turnout (day 0) onto contaminated pasture. faecal egg counts were carried out twice weekly from 15 to 64 days after turnout and the cumulative faecal egg count w ...	1993	8236739
comparison of three enzyme immunoassays for diagnosis of dictyocaulus viviparus infection.	three enzyme-linked immunosorbent assays (elisa) that detect antibodies against dictyocaulus viviparus in cattle were compared for sensitivity, specificity and seroconversion after primary infection. these assays were (i) an indirect elisa with crude somatic antigens from adult d. viviparus (ca-elisa), (ii) an indirect elisa with purified antigens (sa-elisa) isolated from somatic antigens of adult d. viviparus and (iii) a competition elisa with antigen purified with anion chromatography in combi ...	1993	8249247
description of ostertagia ostertagi and ostertagia leptospicularis hybrids in experimentally infected sheep.	hybrids of ostertagia ostertagi and ostertagia leptospicularis, derived from experimental infections in sheep, are described. morphometrics of the hybrids were intermediate between those of parental lines for a large range of parameters (distance from apex to cervical papillae and length of esophagus for males and females, length of spicules for males, and length of vestibule, distance from vulva to the end of tail, width of tail at anus). the morphological relationship between hybrids and their ...	1993	8277380
sds-page profiles of somatic proteins from third-stage infective larvae of ostertagia ostertagi and cooperia oncophora.	sodium dodecyl sulfate-polyacrylamide gel electrophoresis (sds-page) profiles of somatic proteins from third-stage infective larvae of ostertagia ostertagi and cooperia oncophora were evaluated using laser densitometry. several protein bands were present from both parasite preparations. a few bands from each parasite appeared to be unique. purification of these proteins for use in serologic monitoring of cattle naturally infected with o. ostertagi and c. oncophora should allow circumvention of c ...	1993	8291192
ostertagia, haemonchus, cooperia, and oesophagostomum: construction and characterization of genus-specific dna probes to differentiate important parasites of cattle.	partial genomic dna libraries for four common cattle parasites, ostertagia ostertagi (oo), haemonchus placei (hp), cooperia oncophora (co), and oesophagostomum radiatum (or), were generated and differentially screened with radiolabeled homologous and heterologous genomic dna. clones were identified from each parasite species which did not cross react with dna from the heterologous genera by southern blot or slot-blot analyses. four clones, poo2, php2.1, pco2, and por14 were chosen for further ex ...	1994	8299764
efficacy of injectable abamectin against gastrointestinal tract nematodes and lungworms of cattle.	efficacy of abamectin against gastrointestinal tract nematodes and lungworms of cattle was determined in 4 experiments. the first 2 experiments were controlled trials in which efficacy was determined at necropsy in calves with either experimentally induced (n = 14) or naturally acquired (n = 16) infections. half the calves in each experiment were treated with abamectin (200 micrograms/kg of body weight, sc), and half were left untreated as controls. efficacy was > 99% against adult stages of dic ...	1994	8192257
parasite control in transhumant situations.	transhumance is defined as 'seasonal moving of livestock to regions of different climate'. it is an integral part of livestock production in many parts of the world and takes several forms including moving of livestock from lowland to mountainous pastures or from dry to humid areas. the impact of transhumance on parasite populations of livestock and on parasite control is described, mainly using examples from europe. the epidemiology of trichostrongylidosis of cattle, mainly caused by ostertagia ...	1994	7846845
ingestion of host immunoglobulin by three non-blood-feeding nematode parasites of ruminants.	host immunoglobulin was detected in homogenates of adult worms or fourth stage larvae of haemonchus contortus, ostertagia ostertagi, o circumcincta and dictyocaulus viviparus, but not in preparasitic third stage larvae of h contortus. all the worms had been washed in detergent before being homogenised to remove any immunoglobulin adhering to the cuticle. this procedure, the concentrations of immunoglobulin detected and observations on sections of the worms stained with fluorescent anti-sheep imm ...	1994	7871262
nematode burdens and productivity of grazing cattle treated with a prototype sustained-release bolus containing ivermectin.	one hundred and twenty four-month-old hereford-friesian cross heifers weighing from 88 to 130 kg were divided into two equal groups. one group acted as a control with each animal receiving one placebo bolus, the other animals received one prototype intraruminal sustained-release bolus designed to deliver approximately 8 mg ivermectin/day for 100 to 120 days. the boluses were administered the day before turnout in mid-may. each group was grazed separately for 167 days on pastures contaminated wit ...	1994	7871690
ostertagia ostertagi: changes in lymphoid populations in the local lymphoid tissues after primary or secondary infection.	the purpose of this study was to begin to define the changes in the local lymphoid tissues that accompany ostertagia ostertagi infection in naive and immunized calves. abomasal lymph nodes were taken from calves beginning as early as 2 days post-infection. phenotypic changes in the resulting lymphocyte populations were assessed by flow cytometry utilizing monoclonal antibodies specific for the cell surface determinates cd2, cd4, and cd8. changes in antigen specificity were determined by limiting ...	1994	7886908
identification and isolation of a 19.7 kda ostertagia ostertagi specific antigen and evaluation of its potential for immunodiagnosis.	ostertagia ostertagi adult worm extracts were analysed by western blotting using sera from calves experimentally infected with o. ostertagi and cooperia oncophora. strong differences in antigen recognition were noticed, even between animals from the same group. two ostertagia specific antigens with apparent molecular mass of 19.7 (ooa19.7) and 20.7 kda (ooa20.7) were identified. one of them (ooa19.7) was purified by three subsequent chromatographic steps, i.e. gelfiltration, ion-exchange and rev ...	1994	7928070
an attempt to implement the nematode-trapping fungus duddingtonia flagrans in biological control of trichostrongyle infections of first year grazing calves.	an attempt was made to control ostertagia ostertagi by feeding the nematode-trapping fungus duddingtonia flagrans (dsm 6703) to grazing calves. one group of calves (group e) was fed the fungal material in the first two months of the grazing season while another group was a non-treated control group (group c). group e showed significantly lower faecal egg count in august and september. on four occasions in july and september, the herbage larval counts were significantly lower on the plot with the ...	1994	7930461
effectiveness of doramectin for treatment of experimentally induced gastrointestinal tract larval nematode infections in calves.	anthelmintic efficacy of doramectin, a macrocyclic lactone of the avermectin family, was evaluated against larval parasitic nematodes in calves. the investigational product was given sc at a dosage of 0.2 mg/kg of body weight to 10 calves infected 6 days previously with third-stage larvae of the genera haemonchus, ostertagia, cooperia, and nematodirus. ten additional calves with identical larval exposure were given saline solution sc also at 6 days after inoculation, and served as the nonmedicat ...	1994	7944021
antigenic analysis of dictyocaulus viviparus by use of test-positive bovine sera.	an antigen extract of dictyocaulus viviparus was analyzed by use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and the antigen-recognition patterns of serum antibody from cattle not infected, cattle infected with d viviparus, and cattle with unknown history of d viviparus were analyzed by the use of elisa and western blotting techniques. cross-reactive antibody-recognition patterns were determined by comparing western blots of d viviparus-positive sera with blots of d viviparus-n ...	1994	7998700
treatment of multiple resistant field strain of ostertagia spp. in cashmere and angora goats.	a multiple resistant field strain of gastro-intestinal nematodes was detected in cashmere and angora goats imported from new zealand. different treatments with three types of broad spectrum anthelmintics (albendazole, levamisole/tetramisole and ivermectin) at various dose rates are described. satisfactory effect in angora goats was not achieved until all three anthelmintics were administered simultaneously at twice the normal sheep dose. post mortem worm counts and identification revealed that t ...	1994	8070950
interactions between ostertagia ostertagi and cooperia oncophora in calves.	development of immunity to ostertagia ostertagi and cooperia oncophora and interactions between both species in primed calves were investigated after homologous, heterologous and concurrent challenge infections. worm counts, faecal egg output, igg1 and igg2 antibodies and the presence of globule leucocytes were used to evaluate the possible interactions. results show that immunity build-up against o. ostertagi is slow in comparison with c. oncophora. the presence of early fourth-stage larvae and ...	1995	7732636
a comparison of early and mid grazing season suppressive anthelmintic treatments for first year grazing calves and their effects on natural and experimental infection during the second year.	a comparison was made of the efficacy and parasitological sequelae over 2 years, of continuous and intermittent periods of anthelmintic suppression applied both early and in the middle of the first grazing season of calves. five groups of 15 calves grazing separate paddocks within the same field were allotted to one of the following treatment regimes during their first year at grass: group 1, untreated controls; group 2, treated with ivermectin injections at 3, 8 and 13 weeks after turnout; grou ...	1995	7732654
persistent efficacy of moxidectin against dictyocaulus viviparus and ostertagia ostertagi in cattle.		1995	7771074
efficacy of a spring strategic fenbendazole treatment program to reduce numbers of ostertagia ostertagi inhibited larvae in beef stocker cattle.	efficacy of a spring strategic treatment program with fenbendazole (fbz) to reduce the accumulation of ostertagia ostertagi inhibited early fourth-stage larvae (el4) was investigated in two groups of crossbred beef heifers which were 7-9 months of age and ranged in weight from 155 to 223 kg. the cattle were allocated to groups and treated on 27 april (day 0). group 1 calves served as nontreated controls. group 2 calves were treated with fbz 10% drench suspension at 5 mg kg-1 on day 0 and with 6- ...	1995	7483236
persistent anthelmintic activity of ivermectin against gastrointestinal nematodes of cattle.	two experiments were conducted to determine persistence of ivermectin (ivm) anthelmintic activity. in the first experiment, the injectable (inj) formulation at a dosage of 200 micrograms/kg of body weight and pour-on (po) formulation at a dosage of 500 micrograms/kg were compared in 5 groups of calves (n = 6/group). calves were treated at 14 and 7 days prior to experimentally induced infection. experimental groups were: 1--untreated, infected controls; 2--ivm po, day -14; 3--ivm po, day -7; 4--i ...	1995	7486394
influence of early season moxidectin treatments on acquisition of immunity to ostertagia ostertagi in calves.		1995	7502955
efficacy of ivermectin pour-on against ostertagia ostertagi infection and residues in the american bison, bison bison.	sixteen american bison, bison bison, were artificially infected with 10(5) infective stage larvae of ostertagia ostertagi on 21 april 1993. at 42 days post-infection eight bison were treated with 0.5% ivermectin pour-on (500 micrograms/kg bodyweight) and eight treated with the carrier only. bison were necropsied 17 and 18 days post-treatment (21 and 22 june 1993, respectively). mean (+/- se) of 5,413 (+/- 1,716) adults and 565 (+/- 305) immature o. ostertagi were recovered at necropsy from bison ...	1995	7563426
anthelmintic profile of the cyclodepsipeptide pf1022a in in vitro and in vivo models.	a novel cyclodepsipeptide of fungal origin, pf1022a, recently was reported to have anthelmintic activity. to supplement published reports and determine potential utility of pf1022a as a ruminant anthelmintic, the compound was examined in in vitro and in vivo models. assays used measured motility of haemonchus contortus (intrinsic drug potency), atp levels (parasite death), and activity against h. contortus, ostertagia ostertagi, and trichostrongylus colubriformis in the jird (spectrum, potency, ...	1995	7592027
an evaluation of abamectin given at turnout and six weeks after turnout for the control of nematode infections in calves.	two groups of 16 set-stocked calves were used to evaluate a new strategy for the prevention of parasitic bronchitis and parasitic gastroenteritis. one group was left untreated while the calves in the other were treated with abamectin at 0.2 mg/kg at turnout and again six weeks later. the treatment prevented the output of nematode eggs and lungworm larvae in faeces for at least 70 days. the number of infective larvae subsequently appearing on the pasture was reduced by 90.2 per cent and the infec ...	1995	7604518
bilateral, perivulval cuticular pores in trichostrongylid nematodes.	a new hypodermal gland was discovered in female nematodes of the family trichostrongylidae. because the new structure appears to be associated with the vulva, it was named the perivulval pore. it is similar, based on light and scanning electron microscopy, to phasmids that are located laterally on the tails of nematodes of the class secernentea. like phasmids, perivulval pores are paired and bilateral, with cuticular ducts to the surface in the areas of the lateral chords. they are located sligh ...	1995	7623208
immunisation of calves with ostertagia ostertagi fourth stage larval antigens failed to protect calves from infection.	excretory-secretory and somatic antigens of ostertagia ostertagi fourth stage larvae, emulsified with complete freund's adjuvant, were intraperitoneally administered to calves on three occasions. two weeks after the last immunisation all calves were infected with a single dose of 130,000 o. ostertagi third stage larvae. all animals were necropsied 25 days after infection. the immunisation procedure resulted in igg1 and igg2 antibodies, however no protective immunity was induced as o. ostertagi w ...	1995	7657462
effect of treatment with an ivermectin sustained-release bolus on productivity of stocker beef calves.	three groups of 30 crossbred beef steers, 8-10 months of age and ranging in weight from 158 to 320 kg, were used to compare effects of treatment with an ivermectin sustained-release bolus or two ivermectin injectable treatments on parasite control and productivity in relation to untreated controls during a 168 day winter-spring grazing period. each group of 30 consisted of five cattle on each of six separate 1.6 ha pastures. treatments on day 0 (12 december) were: group 1: untreated controls; gr ...	1995	7676602
amplification and characterization of cysteine proteinase genes from nematodes.	in order to isolate proteinase genes from parasitic nematodes by polymerase chain reaction (pcr) techniques, we employed a pair of consensus oligonucleotide primers designed to anneal to the active site cysteine (primer ncpc) and asparagine (primer ncpn) coding regions of cysteine proteinases. the primers were biased toward the nucleotide and codon usages of cysteine proteinase genes of nematodes and were based on the consensus nucleotide sequences flanking the active site residues of genes from ...	1995	8525283
cloning and sequencing of an excretory/secretory antigen from ostertagia ostertagi fourth-stage larvae containing multiple tandem repeats.		1995	8538694
immunodiagnosis of taenia saginata in cattle using hydrophobic antigens from t. hydatigena metacestode cyst fluid.	hydrophobic fractions isolated from cyst fluid of taenia hydatigena metacestodes, obtained from naturally infected goats from tanzania, were used in an indirect elisa and in immunoblot (western or dot blot) procedures. the use of the most hydrophobic fractions of the cyst fluid proved to result in a better diagnostic discrimination in elisa than the more hydrophilic fractions. best diagnostic ratio between responses from t. saginata infected and non-infected cattle was achieved when using horse- ...	1995	8541896
host movement and the genetic structure of populations of parasitic nematodes.	mitochondrial dna (mtdna) sequence data were used to compare the population genetic structures of five species of parasitic nematodes from three different hosts: ostertagia ostertagi and haemonchus placei from cattle, h. contortus and teladorsagia circumcincta from sheep, and mazamastrongylus odocoilei from white-tailed deer. the parasites of sheep and cattle showed a pattern consistent with high gene flow among populations. the parasite of deer showed a pattern of substantial population subdivi ...	1995	8582607
persistent activity of ivermectin topical and moxidectin injection against ostertagia ostertagi and dictyocaulus viviparus in calves.		1995	8693675
efficacy of doramectin against naturally acquired adult and inhibited larval infections by some nematode parasites in cattle in new zealand.	a study was conducted to determine the therapeutic efficacy of 1% doramectin injected subcutaneously at 200 microg/kg into cattle harbouring naturally acquired infections of inhibited ostertagia ostertagi larvae. sixteen yearling friesian bulls, grazed without anthelmintic treatment throughout the autumn-winter, were selected on the basis of similar body weights and serum pepsinogen activities. after removal from pasture on day -23 they were weighed and randomly assigned to two treatment groups ...	1995	16031810
efficacy of doramectin against experimental infections by some nematode parasites in cattle in new zealand.	a study was undertaken to determine the efficacy of the novel avermectin, doramectin, against experimental larval and adult infections of three species of nematode parasite important to cattle production in new zealand. eighteen worm-free dairy bull beef calves were randomly allocated on live weight to three similar treatment groups. each calf was given 30,000 ostertagia ostertagi, 20,000 cooperia spp. and 10,000 trichostrongylus axei infective larvae as a single dose. one group was treated with ...	1995	16031811
influence of chemoprophylaxis on protective immunity to nematodes in cattle: a two-year study comparing four control strategies.	a two-year study was conducted in three sequential phases. initially, four matched groups of nine calves grazing similar pastures were subjected to different chemoprophylactic control programmes while a fifth group acted as unprotected controls. after being housed in the autumn, three calves from each group and two parasite-naive controls were challenged experimentally with ostertagia ostertagi, cooperia oncophora and dictyocaulus viviparus. post mortem worm counts revealed gradations of protect ...	1995	8748170
the effects of first-season strategic and tactical ivermectin treatments on trichostrongylosis in the first- and second-season grazing.	a 2 year study was conducted to evaluate the effects of first-season strategic or tactical treatments with ivermectin on trichostrongylosis in heifer calves in the first and second-season grazing. three groups of each eight holstein-friesian calves were turned out in early may onto a permanent pasture naturally contaminated with trichostrongyle larvae. two of these groups were given ivermectin either as strategic treatments (weeks 3, 8 and 13 after turnout) or as tactical treatments (weeks 14, 1 ...	1996	8888555
a tandemly repetitive dna sequence is present at diverse locations in the genome of ostertagia circumcincta.	a novel repetitive dna sequence in the sheep parasitic nematode ostertagia circumcincta was cloned and sequenced. this 1.2-kb sequence (oc1b) was not found in the closely related cattle parasite ostertagia ostertagi, nor in the more distantly related sheep parasites haemonchus contortus or trichostronylus colubriformis. sequences similar to oc1b were found at various genomic locations and contained a pair of 33-bp direct repeats. oc1b also contained a single copy of a 218-bp sequence (designated ...	1996	8890746
efficacy of moxidectin pour-on against gastrointestinal nematodes and dictyocaulus viviparus in cattle.	twenty crossbred beef heifer calves were used for an efficacy evaluation of 0.5% moxidectin pour-on against gastrointestinal nematodes and dictyocaulus viviparus. the latter parasite and bunostomum phlebotomum were the target species. the calves were exposed to natural infection on pasture from late september to december 22. additionally, all calves were experimentally infected with b. phlebotomum at 71 and 29 days before treatment and with d. viviparus at 29 days before treatment. the 20 calves ...	1996	8893482
prevalence and epidemiology of trichostrongylids in wyoming cattle with consideration of the inhibited development of ostertagia ostertagi.	during 1988, monthly collections of abomasa and the cranial portion of the small intestine of 208 native wyoming cattle were examined for adult and larval helminth parasites. egg counts were performed on colonic faecal specimens. the animals ranged from 7 months to 8 years of age and were sampled at slaughter houses or diagnostic laboratories from five different counties in the state. most of the cattle had ranged for a long time on non-irrigated, high altitude grass plains from about 1250 to 25 ...	1996	8893483
efficacy of moxidectin 0.5% pour-on against naturally acquired nematode infections in cattle.	the efficacy of 0.5% moxidectin pour-on at two dosages was evaluated in 30 cattle with naturally acquired gastrointestinal nematode infections. the cattle were ranked according to pretreatment fecal egg counts and body weights, and were randomly assigned from replicates to three treatment groups. the mean number of trichostrongyle eggs in pretreatment fecal samples did not differ among the groups. groups i and ii received 0.5% moxidectin pour-on at dosages of 0.25 mg moxidectin per kg body weigh ...	1996	8916402
digital image analysis and identification of eggs from bovine parasitic nematodes.	computer-assisted microscopy and multivariate statistics were used to establish and evaluate a procedure for identification of bovine strongylid eggs. ostertagia ostertagi, cooperia oncophora, haemonchus placei, trichostrongylus axei, and oesophagostomum radiatum eggs were obtained from faeces voided by monospecifically infected calves. images of single eggs (400 x magnification) were recorded by a ccd camera fitted onto a microscope and digitized on a pc. after separation of eggs from the image ...	1996	8960211
induction of traps by ostertagia ostertagi larvae, chlamydospore production and growth rate in the nematode-trapping fungus duddingtonia flagrans.	biological control of parasitic nematodes of domestic animals can be achieved by feeding host animals chlamydospores of the nematode-trapping fungus duddingtonia flagrans. in the host faeces, d. flagrans develop traps that may catch nematode larvae. in experiments on agar, d. flagrans had a growth rate between 15 and 60 mm/week at temperatures between 20 and 30 degrees c. the presence of nematodes induces the fungus to produce traps. the rate of trap formation in d. flagrans has an optimum at 30 ...	1996	8960226
seasonal pattern of inhibition of ostertagia ostertagi in calves in northeast mississippi.	the composition of, and seasonal changes in, populations of gastrointestinal parasites of calves in northeast mississippi were determined for 10 months post-weaning. after weaning on 15 october, 20 mixed breed beef steers were grazed together on a 4 ha fescue/bermudagrass pasture. from november through august of the following year, two of the calves were removed each month for necropsy and counting of gastrointestinal nematodes. eight species of worms were found: haemonchus placei, ostertagia os ...	1996	8983154
the epidemiology of gastrointestinal nematode infections in communal cattle and commercial beef cattle on the highveld of zimbabwe.	an epidemiological study of gastrointestinal nematode infections of cattle was conducted on the highveld of zimbabwe from june 1993 to may 1995. the study was carried out in two communal areas, two conventional beef farms and two commercial beef farms with irrigated pastures. on all farms/areas, faecal egg counts were low (< 500 eggs per g faeces) during the dry season. during the rainy season faecal egg counts were highest in communal areas and lowest in conventional beef farms. those of irriga ...	1996	9011020
monthly fluctuations of worm burdens and hypobiosis of gastrointestinal nematodes of calves in extensive management systems in the pyrenees (spain).	monthly fluctuations of worm burdens and arrested development of gastrointestinal nematodes in cattle from a mountainous region of spain were studied. fourteen previously helminth-naive calves grazed together with a herd of 120 cattle from may to november following the traditional extensive grazing system used in mountainous regions of spain (permanent calves). each month, throughout the grazing season, two helminth-naive calves (tracer calves) were added to the herd and allowed to graze for 4 w ...	1996	9017870
the effect of truncated infections with ostertagia ostertagi on the development of acquired resistance in calves.	the relative contribution of the third (l3), fourth (l4) and adult stages of ostertagia ostertagi to the development of immunity was assessed in calves which were either continuously infected during 21 weeks or subjected to infections truncated by anthelmintic treatment at the l3 or l4 stage. a fourth group remained uninfected (control group). faecal samples and blood samples were collected weekly for faecal egg counts and determination of pepsinogen and antibody levels. only the continuously in ...	1996	9017885
toward practical biological control of parasitic nematodes in domestic animals.	in a series of laboratory and field experiments where the nematophagous fungus arthrobotrys oligospora was mixed directly with feces it has been demonstrated that it is possible to use nematophagous fungi for biological control of animal parasitic nematodes. a procedure used for selection of nematophagous fungi that can pass the digestive tract of ruminants, horses, and pigs is described. the selected fungus, duddingtonia flagrans, has been used in further field experiments, and the results have ...	1996	19277128
the effects of early-season treatments with doramectin on set-stocked calves naturally exposed to trichostrongyles.	a study was carried out to evaluate the effects of strategic early-season treatments with doramectin on first-season grazing calves exposed to trichostrongylid infection on a naturally contaminated pasture. two groups of cross-bred limousine/red danish calves were turned out in early may on two plots that were similar with respect to size and herbage infectivity. they grazed separately until housing in early october. one of these groups was given doramectin at turnout and 10 weeks later, while t ...	1996	8693699
isolation, characterization and immunolocalization of a globin-like antigen from ostertagia ostertagi adults.	western blot analysis using an anti-globin rabbit serum rb94 revealed a major band of 17 kda in extracts of ostertagia ostertagi adults and 4th-stage larvae. the adult stage globin-like antigen (ooadglb) was purified from total worm extracts by liquid chromatography. the protein has an estimated molecular mass of 36 kda under non-reducing conditions, suggesting a dimeric structure containing 2 non-covalently linked 17 kda monomers. tryptic peptides were sequenced and showed strong similarities w ...	1996	8710416
eprinomectin: a novel avermectin for use as a topical endectocide for cattle.	eprinomectin (mk-397 or 4"-epi-acetylamino-4"-deoxy-avermectin b1) is a novel avermectin selected for development as a topical endectocide for all cattle, including lactating dairy cows. herein, we show its anthelmintic, insecticidal and miticidal activity. to determine its anthelmintic capabilities, eprinomectin was tested topically on jersey calves at 0.08, 0.2, or 0.5 mg kg-1 in a probe formulation against experimental infections of adult haemonchus placei, ostertagia ostertagi, trichostrongy ...	1996	9024867
viability of infective larvae of haemonchus contortus, ostertagia ostertagi, and trichostrongylus colubriformis following exsheathment by various techniques.	various techniques were examined to determine optimum conditions for exsheathing infective larvae of 3 important ruminant parasites (haemonchus contortus, ostertagia ostertagi, and trichostrongylus colubriformis). in repeated experiments, aliquots of 10(5)-10(6) infective larvae, 1-2 mo old, of each parasite were incubated in each of 4 exsheathing media (distilled water, earle's balanced salt solution + carbon dioxide, nematode washing buffer + carbon dioxide, or sodium hypochlorite) for 1 or 18 ...	1996	8627476
the synlophe and other structural characteristics of sarwaria bubalis (nematoda: trichostrongyloidea) from cattle in guyana.	the synlophe (longitudinal, surface cuticular ridges) of sarwaria bubalis is described for the first time. it is a tapering lateral synlophe of about 40 ridges. the synlophe of s. bubalis is similar to that of ostertagia ostertagi but markedly different from that of species of spiculopteragia and mazamastrongylus. new information is provided also on the structure of the esophagus and perivulval pores. the esophageal valve is more than twice as long as wide. the bilateral perivulval pores were lo ...	1996	8627485
persistent efficacy of abamectin and doramectin against gastrointestinal nematodes of cattle.	to assess the persistent activity of injectable formulations of abamectin and doramectin against gastrointestinal nematodes of cattle.	1997	9034496
effects of ostertagia ostertagi on gastrin gene expression and gastrin-related responses in the calf.	1. infection with the bovine abomasal nematode ostertagia ostertagi results in a loss of acid-secreting parietal cells and an increase in gastric ph. the effects of an experimental infection on gastrin mrna expression, blood and tissue gastrin concentrations, the different molecular forms of gastrin in each, and pyloric mucosal chromogranin a-derived peptides were investigated in the calf. 2. an increase in blood gastrin concentrations in the infected group reached a peak by day 28 postinfection ...	1997	9051591
efficacy of doramectin for treatment of experimentally induced infection with gastrointestinal nematodes in calves.	to determine the efficacy of injectable doramectin against experimentally induced infections with adult and larval (l4) stages of gastrointestinal nematodes in calves.	1997	9055975
persistent efficacy of topical moxidectin against dictyocaulus viviparus and ostertagia ostertagi.	the persistent activity of moxidectin topically administered at the dose rate of 0.5 mg kg-1 bodyweight was evaluated against experimental nematode infection in 30 calves randomly allocated to six groups. five groups were treated on days -42, -35, -28, -21 and -14. the 6th group remained untreated as a control. on day 0, the calves were infected experimentally with 1000 dictyocaulus viviparus and 50,000 ostertagia ostertagi larvae and killed 3 weeks later. the formulation of moxidectin showed ex ...	1997	9066064
evaluation of the persistence of the effect of ivermectin and abamectin against gastrointestinal and pulmonary nematodes in cattle.	the persistence of the effect of ivermectin and abamectin against gastrointestinal nematodes and lungworm in cattle was evaluated in two trials, each involving 28 animals. groups of seven cattle either remained untreated, or were treated topically with ivermectin at 500 micrograms/kg bodyweight or subcutaneously with either ivermectin or abamectin at 200 micrograms/kg bodyweight. starting on the day of treatment the cattle were given daily trickle infections with various infective nematode larva ...	1997	9090034
the presence of an early l4 population in relation to the acquired resistance of calves naturally infected with ostertagia ostertagi.	the aim of the present study was to determine if the presence of inhibited l4 ostertagia ostertagi populations during the housing period influenced the level of acquired immunity in calves at the start of the second grazing season. four groups (a-d) of first season grazing calves were turned out onto a heavily infected pasture for five months, while the fifth group (e) was kept as uninfected controls. at housing all group a calves were necropsied for worm counts. a mean total of 78915 ostertagia ...	1997	9106955
nematocidal efficacy of eprinomectin, delivered topically, in naturally infected cattle.	to assess the nematocidal efficacy of eprinomectin in naturally infected cattle.	1997	9185967
epidemiological observations on gastrointestinal nematode infections in grazing cow-calf pairs in belgium.	the epidemiology of gastrointestinal helminth infections in beef cows and calves on pasture was studied in belgium during the 1990 and 1992 grazing seasons. weight gain, faecal egg counts, generic differentiation of infective larvae, serum pepsinogen levels, herbage larval counts and worm burdens of tracer calves were used as parameters. in study 1 two groups of ten cows with their spring-born calves grazing on separate pastures (a and b) were monitored during the 1990 grazing season. ostertagia ...	1997	9187031
effect of simulated rain, coat length and exposure to natural climatic conditions on the efficacy of a topical formulation of eprinomectin against endoparasites of cattle.	a series of five controlled studies involving 114 cattle were conducted in australia, north america and the united kingdom to examine the effect of simulated rain, coat length and exposure to natural climatic conditions, on the efficacy of a topical formulation of eprinomectin against nematode parasites of cattle. in all trials infections were induced with a range of bovine nematode species and treatment was applied when the majority of nematodes were mature. in one study, simulated rain was app ...	1997	9187034
the influence of a cooperia oncophora priming on a concurrent challenge with ostertagia ostertagi and c. oncophora in calves.	the development of immunity to ostertagia ostertagi and cooperia oncophora and interactions between these species were investigated in experimentally infected calves. parasitological, serological and histological parameters were used for assessing immune responses. no conclusive evidence of an effect of c. oncophora on the course of an o. ostertagi infection in calves could be shown. following a challenge with c. oncophora and o. ostertagi of c. oncophora primed calves, no significant reductions ...	1997	9195718
evaluation of an elisa for the routine diagnosis of dictyocaulus viviparus infections in cattle.	an enzyme-linked immunosorbent assay (elisa) that detects antibodies against dictyocaulus viviparus in experimentally and naturally infected cattle was evaluated for its sensitivity, specificity, the moment of seroconversion and persistence of the anti-d. viviparus response and precision. the first three parameters were compared with those of an indirect haemagglutination assay (iha). specificity and sensitivity of both assays were assessed in sera collected from calves experimentally infected w ...	1997	9195719
use of cloned excretory/secretory low-molecular-weight proteins of cooperia oncophora in a serological assay.	the potential of cooperia oncophora excretory/secretory (es) proteins as antigens in a serological assay which aims to establish exposure levels in cattle was assessed. es proteins were analyzed by one- and two-dimensional polyacrylamide gel electrophoresis and immunoblotting. the n-terminal domains of two es proteins were sequenced, and the corresponding cdnas were cloned. two cdnas, designated coes14.0 and coes14.2, were expressed in escherichia coli. the recombinant proteins were tested in an ...	1997	9196182
induction and suppression of lymphocyte proliferation by antigen extracts of ostertagia ostertagi.	to obtain an insight into the responses of t-cells of cattle to ostertagia ostertagi, the responses of peripheral blood and lymph node lymphocytes to o. ostertagi antigen extracts were determined in both exposed and naive calves. the lymphocyte responses induced by o. ostertagi antigen extracts of the third (l3) and fourth (l4) larval stages, as well as adult worms, were analysed. although peripheral blood lymphocyte responses were very low or absent, abomasal lymph node lymphocytes of exposed a ...	1997	9239839
isolation and phenotypic characterization of abomasal mucosal lymphocytes in the course of a primary ostertagia ostertagi infection in calves.	isolation and characterization of surface marker phenotypes of abomasal intraepithelial (iel), lamina propria (lpl) and abomasal lymph node lymphocytes (abln) from uninfected calves were conducted, and the dynamics of change in these populations during the course of a primary ostertagia ostertagi infection were defined. to obtain viable iel and lpl from the abomasal mucosa of cattle, a modified isolation method was developed. the phenotypic characterization of abomasal lymphocytes was accomplish ...	1997	9239841
therapeutic and prophylactic efficacy of the ivomec sr bolus against nematodes and psoroptes ovis in cattle weighing more than 300 kg at the time of treatment.	three trials using 50 european breed cattle were conducted to evaluate the therapeutic and prophylactic efficacy of the ivomec sr bolus against nematodes (2 trials) and psoroptes ovis (1 trial) in cattle weighing more than 300 kg at the time of treatment. the ivomec sr bolus proved to be highly effective against economically important gastrointestinal and pulmonary nematodes (ostertagia ostertagi, trichostrongylus axei, cooperia punctata, oesophagostomum radiatum, dictyocaulus viviparus) and imp ...	1997	9272566
cytokine profile induced by a primary infection with ostertagia ostertagi in cattle.	changes that occur in the local draining lymph nodes including, changes in cell surface markers and cytokine gene expression were studied over the first 4 weeks of a primary, ostertagia ostertagi infection of the abomasum. cells recovered from the abomasal lymph nodes (abln) after infection showed a decrease in the percentage of cd3+ cells, and an increase in the percentage of igm+ cells and cells bearing the tcr1 marker. these changes were coincident with an increase in the proportion of activa ...	1997	9343340
persistent efficacy of doramectin against experimental challenge with ostertagia ostertagi in cattle.	two studies were conducted in north america to evaluate the persistent efficacy of doramectin injectable solution against experimental challenge with infective larvae of ostertagia ostertagi. in both studies, four groups of 10 randomly-assigned calves, negative for trichostrongyle-type eggs on fecal examination, were treated subcutaneously in the midline of the neck with saline (1 ml 50 kg-1) on day 0 or doramectin (200 micrograms kg-1 = 1 ml 50 kg-1) on day 0, 7, or 14. two additional calves fr ...	1997	9403972
comparative persistent efficacy of doramectin, ivermectin and fenbendazole against natural nematode infections in cattle.	a study was conducted in argentina, to investigate the period of protection of a single injection of doramectin administered subcutaneously (s.c.) at 200 micrograms kg-1 (1 ml/50 kg) compared with single treatments of ivermectin (200 micrograms kg-1 s.c.) and fenbendazole (5 mg kg-1 p.o.), against field infections of gastrointestinal parasites of cattle. eighty-three animals were selected and ranked on the basis of serial fecal egg counts (e.p.g.'s). from this group, three animals were slaughter ...	1997	9403975
quantification of cytokine gene expression in lamina propria lymphocytes of cattle following infection with ostertagia ostertagi.	changes in cell surface markers and cytokine transcription were analyzed in lamina propria lymphocytes from control animals (noninfected calves) and calves after a single high but nonprotective primary infection with ostertagia ostertagi. flow cytometry of cells recovered from the lamina propria showed an increase in the percentages of igm+, wc1+, and il-2r+-bearing cells 10 days after infection; however, 2 mo after infection, cell staining was comparable to preinfection levels. transcription le ...	1997	9406777
environmental factors influencing transmission.	the free-living stages of gastro-intestinal nematodes on pasture (i.e. eggs, developing and infective larvae) are often overlooked and not considered by producers. the factors that influence the development, survival, distribution, or migratory behavior of the free-living larvae seen on pasture are primarily weather related. the deposition of helminth eggs in feces is the starting point for the contamination of the pasture and the subsequent development of the parasites. the cumulative numbers o ...	1997	9460201
pathophysiology of infection with gastrointestinal nematodes in domestic ruminants: recent developments.	infection with gastrointestinal nematodes, particularly ostertagia species in domestic ruminants, continues to represent an important cause of impaired productivity in temperate parts of the world. the mechanisms responsible for such losses include changes in feed intake, gastrointestinal function, protein, energy and mineral metabolism, and body composition, and were described in detail at the last ostertagia workshop (fox, m.t. 1993. pathophysiology of infection with ostertagia ostertagi in ca ...	1997	9460203
immunity development against ostertagia ostertagi and other gastrointestinal nematodes in cattle.	the immunological response to gastrointestinal nematodes is complex and it will take time and financial support to dissect the different components of protective immunity in ruminants. the present review briefly summarises different aspects and manifestations of protective immunity in cattle against gastrointestinal nematodes, especially ostertagia ostertagi, and the factors that may interact with the development of this immunity.	1997	9460204
effects of gastrointestinal nematode infection on the ruminant immune system.	gastrointestinal (gi) nematodes of ruminants evoke a wide variety of immune responses in their hosts. in terms of specific immune responses directed against parasite antigens, the resulting immune responses may vary from those that give strong protection from reinfection after a relatively light exposure (e.g. oesophagostomum radiatum) to responses that are very weak and delayed in their onset (e.g. ostertagia ostertagi). the nature of these protective immune responses has been covered in anothe ...	1997	9460205