Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| seasonal changes and hypobiosis in haemonchus contortus infection in the west african dwarf sheep and goats in the nigerian derived savanna. | a survey was conducted in the nigerian derived savanna (from august 1987 to july 1988) on the seasonal fluctuations in the composition of haemonchus contortus burden of naturally infected west african dwarf sheep and goats. during this period 117 abomasa collected from locally slaughtered animals were processed. male, female as well as immature worms were enumerated. the incidence of haemonchus infection was high (77.8-100%) with no definite seasonal distinction. there was however, a clear seaso ... | 1990 | 2382380 |
| critical controlled test to evaluate resistance of field strains of haemonchus contortus to thiophanate. | following reports of suspected gastrointestinal strongylid nematode resistance to thiophanate in sheep and goats at sokoine university of agriculture (sua), tanzania, field strains of haemonchus contortus, one from sua and another from kimamba, tanzania, were selected for a critical controlled test to evaluate the efficacy of thiophanate. the sua h. contortus strain in goats showed a marked resistance to thiophanate at an oral dose of 50 mg kg-1 liveweight (efficacy = 24.1%), while the kimamba h ... | 1990 | 2382387 |
| development and survival of haemonchus contortus larvae on pasture at vom, plateau state, nigeria. | the development and survival of the eggs of haemonchus contortus on pasture at vom were studied by depositing faecal pellets on grass plots over a period of 12 months. development and survival to the infective larvae occurred throughout the study except during the dry season months of december to april. more infective larvae were recovered from the herbage in june, july and august than in other months. the survival time of the infective larvae ranged from 2 weeks in october to 10 weeks in june, ... | 1990 | 2382405 |
| molecular cloning and primary sequence of a cysteine protease expressed by haemonchus contortus adult worms. | we have cloned cdnas encoding a 35-kilodalton cysteine protease that is a major component of protective extracts isolated from blood-feeding haemonchus contortus adult worms. near full-length cdnas for the protease were isolated by immunoscreening an adult worm cdna expression library with a rabbit antiserum prepared against the protein eluted from preparative sds gels and by rescreening the library with oligonucleotide probes. the protein predicted from the nucleotide sequence of the cdnas and ... | 1990 | 2385265 |
| experimental haemonchus contortus infection in three breeds of sheep. | nine- to 10-month-old florida native, st. croix and dorset/rambouillet sheep were infected with haemonchus contortus. the primary infection was terminated by anthelmintic treatment 9 weeks later and animals were then reinfected with h. contortus. dorset/rambouillet sheep showed higher fecal egg counts and decreased packed cell volumes and plasma protein levels compared with the other two breeds during the primary infection. however, no breed differences were found in total worm burdens in either ... | 1990 | 2399644 |
| haemonchus contortus with low inhibited development in sheep from the highveld of zimbabwe. | the abomasa of sheep grazing on natural pastures in the highveld of zimbabwe were examined for haemonchus contortus. of 304 abomasa, 213 (70%) harboured h. contortus. the worm burden increased during the rains to reach the peak in february-march. this was followed by a decline with low worm loads throughout the dry season. the fourth stage larvae (l4) accounted for 1-7% of the total h. contortus population, except during july and august when they comprised 22 and 54% of the worm burden, respecti ... | 1990 | 2399655 |
| haemonchus contortus: evidence that the 3a3 collagen gene is a member of an evolutionarily conserved family of nematode cuticle collagens. | rabbit antisera were raised against an 18 amino acid-long peptide that corresponds to the predicted sequence of the carboxy-terminal, nontriple helical region of the haemonchus contortus 3a3 collagen gene. this sequence is highly conserved and diagnostic for members of the col-l collagen family, which includes the 3a3 gene. we find that these antisera react predominantly with multiple, high molecular weight (greater than 68 kda) proteins on western blots of whole worm extracts. the number and mo ... | 1990 | 2404780 |
| haemonchus contortus: a simple procedure for purifying surface proteins from third- and fourth-stage larvae. | surface proteins were solubilized from exsheathed third (xl3)- and fourth (l4)-stage larvae of haemonchus contortus by a one-step extraction procedure involving brief heat treatment of the worms in the presence of buffer and 100 mm sodium chloride. surface proteins also could be preferentially extracted from xl3s, but not from l4s, by heating the worms briefly in 1% sodium dodecyl sulfate. the major proteins extracted by these procedures were similar in molecular weight to those detected by surf ... | 1990 | 2404783 |
| vital staining of glycoprotein secreted by infective third stage larvae of haemonchus contortus prior to exsheathment. | staining of infective third stage larvae of haemonchus contortus prior to exsheathment shows that protein is exuded from the head region and spreads between the cuticles and that a carbohydrate-containing substance is also found between the l2 and l3 cuticles throughout, at exactly the same sites in this nematode. this glycoprotein, which is either secreted from the mouth or the amphids or both is exuded whether or not the larvae have been stimulated to exsheath. slight staining was also sometim ... | 1990 | 1699905 |
| the distribution and localization of the stage-specific gp31 antigen from infective ostertagia circumcincta larvae. | the 31,000 mol. wt glycoprotein (gp31) antigen of infective third-stage (l3) ostertagia circumcincta larvae was shown, by surface labelling experiments and immunofluorescent antibody staining of whole larvae and larval sections, to be distributed internally. when transverse sections of l3 o. circumcincta, taken from the anterior pharyngeal region, were further examined by electron microscopy, after immunogold staining with rabbit anti-gp31 antiserum, the gp31 antigen was found to be specifically ... | 1990 | 1690183 |
| response to helminth infection of sheep selected for resistance to haemonchus contortus. | lines of merino sheep selected for increased (irh) and decreased (drh) resistance to haemonchus contortus were compared with an unselected (ch) line, after approximately four generations of selection. measurements were recorded on 69 irh, 47 drh and 84 ch animals. following artificial challenge with h. contortus, the irh line had significantly (p less than 0.001) lower faecal egg counts than the ch and drh lines (2730, 12,720 and 17,400 epg, respectively). significant differences (p less than 0. ... | 1990 | 2074125 |
| the intensity of resistance by mature merino ewes against haemonchus contortus and trichostrongylus colubriformis in single-species and combined-species infection. | three-year-old, non-lactating and non-pregnant merino ewes, raised on pasture under a program of strategic treatment with anthelmintic and found to be extremely resistant to "trickle" infection with haemonchus contortus, were given single-dose infections with either h. contortus or trichostrongylus colubriformis or both species together. the purpose was to ascertain the intensity of protective immunity against the 2 parasites in sheep with immunity acquired from a presumably slight exposure to i ... | 1990 | 2076067 |
| effect of haemonchus contortus infection on the clearance of antipyrine, sulfobromophthalein, chloramphenicol, and sulfathiazole in lambs. | a study was made to determine the effect of haemonchus contortus parasitic infection in lambs on the clearance of several iv administered drugs. clearance of sulfobromophthalein or sulfathiazole from the plasma of lambs was unaffected by infection with h contortus. clearance of antipyrine was enhanced by the infection, and thiabendazole treatment did not alter this effect. clearance of chloramphenicol (cap), administered as the succinate ester (caps), was not changed by the infection, but it was ... | 1990 | 2085232 |
| a developmentally regulated cysteine protease gene family in haemonchus contortus. | the nucleotide sequence of a gene encoding a 35-kda thiol protease of the parasitic nematode haemonchus contortus has been determined. the gene, designated ac-2, shares 97% nucleotide sequence identity and 98% amino acid identity with previously characterized ac-1 cdnas encoding the thiol protease. the ac-2 gene spans 8 kb and appears to contain 11 introns, ranging in size from 57 bp to over 5.2 kb. one of the introns interrupts the proposed active site region that is conserved between the h. co ... | 1990 | 2090940 |
| efficacy of some commercial formulations of anthelmintics on haemonchus contortus and trichostrongylus columbianum. | the anthelmintic action of five commercially formulated anthelmintics: assiazine, banminth, nemafax, piperazine and levamisole has been evaluated by observing the effect on egg hatch, motility and mortality of the larvae of trichostrongylus columbianum and haemonchus contortus. assiazine and levamisole inhibited egg-hatch of the helminth ova dose-dependently. nemafax, banminth, and piperazine did not inhibit egg hatch. levamisole and banminth affected the motility of the helminth larvae with sub ... | 1990 | 2093109 |
| infection of immunosuppressed mice with the abomasal nematode parasite of ruminants, haemonchus contortus. | infective larvae of haemonchus contortus established in mice either immunosuppressed with the corticosteroid, dexamethasone, or the cytotoxic drug, cyclophosphamide, or treated with the histamine h2 inhibitor, cimetidine. infections persisted for as long as the immunosuppressive treatment (7 days) and growth of larvae was similar to that seen in sheep. virtually no larvae survived in untreated mice. accordingly, it would appear that adaptive immunity is an important barrier against primary infec ... | 1990 | 2121657 |
| strategies for vaccination against gastro-intestinal nematodes. | a great diversity of gastro-intestinal nematodes parasitise man and his animals. each nematode is antigenically highly complex with distinct developmental stages. the parasites occupy a range of niches in the host gut and have a variety of feeding habits. hosts have evolved only partially successful local immune responses. the host and parasite factors modulating these responses are described. strategies for vaccination are surveyed. it is argued that the best route to successful vaccines will b ... | 1990 | 2132697 |
| studies on the presence and release of proteolytic enzymes (proteinases) in gastro-intestinal nematodes of ruminants. | the proteolytic activity of worm homogenates prepared from the third stage larval (l3) and adult stages of the ovine gastro-intestinal nematodes, nematodirus battus, ostertagia circumcincta, trichostrongylus colubriformis, trichostrongylus vitrinus and haemonchus contortus, and the rodent intestinal nematode, nippostrongylus brasiliensis, has been examined using the protein substrates azocasein, azocoll and elastin-orcein. activity detected in third stage larvae was usually higher than that obse ... | 1990 | 2185170 |
| effect of nilzan and albendazole on the absorptive surfaces of haemonchus contortus (nematoda)--a histoenzymic study. | haemonchus contortus, incubated in 10 micrograms/ml and 50 micrograms/ml concentrations of nilzan and albendazole in tyrode solution were stained for histoenzymatic demonstration of various phosphatases, oxido-reductases and esterases. the intestine showed major alterations after drug treatments. the alkaline phosphatases (akpase), adenosine triphosphatase (atpase), glucose-6-phosphatase, succinic dehydrogenase (sdh), glutamate dehydrogenase (gdh), reduced nicotinamide adenine dinucleotide phosp ... | 1990 | 1963279 |
| a membrane associated glutamate binding protein from caenorhabditis elegans and haemonchus contortus. | 1. a glutamate binding protein has been identified in membrane preparations from the free living nematode, caenorhabditis elegans, and from the parasitic nematode, haemonchus contortus. 2. this putative glutamate receptor was solubilized with 30 mm octyl-b-glucoside and partially purified by anion exchange and gel filtration chromatography. 3. an 80-fold purification with recovery of 75% of the glutamate binding activity was achieved. 4. the soluble c. elegans binding protein displayed a kd for ... | 1990 | 1977551 |
| molecular biology of the cuticle collagen gene families of caenorhabditis elegans and haemonchus contortus. | 1990 | 1978527 | |
| the localization of somatostatin-like immunoreactivity in the alimentary tract of the sheep with observations on the effect of an infection with the parasite haemonchus contortus. | cells containing somatostatin immunoreactivity were localized in the alimentary tract of parasite-free sheep by indirect immunocytochemistry, using an antiserum raised to ovine somatostatin. nerve fibres showing somatostatin-like immunoreactivity were identified in the oesophagus, reticulum wall and groove, rumen pillar and wall, omasum sulcus and abomasum. varicose fibres were found in the myenteric plexuses of the duodenum, jejunum, ileum and colon. the greatest distribution of endocrine cells ... | 1990 | 1980195 |
| resistance to benzimidazoles in haemonchus contortus of sheep in tanzania. | this study was undertaken to establish whether resistance to benzimidazole anthelmintics was present in gastrointestinal nematodes of sheep and goats at the university farm of sokoine university of agriculture, morogoro, tanzania. groups of lambs were treated with albendazole at 3.8 mg/kg (recommended dose rate), 5.6 mg/kg and 10.0 mg/kg and a fourth group was untreated. seven days after treatment, faecal egg count reductions (fecr) were found to be 94.3%, 97.6% and 99.3% and 14 days after treat ... | 1990 | 1980804 |
| molecular analysis of selection for benzimidazole resistance in the sheep parasite haemonchus contortus. | the molecular basis for the resistance of the sheep parasitic nematode haemonchus contortus to the benzimidazole (bz) group of anthelmintics was investigated. three bz-susceptible and three resistant populations from different geographical locations were characterized with respect to the egg-hatch assay with thiabendazole (tbz), mebendazole (mbz) binding tests and restriction fragment length polymorphism (rflp) after southern blotting. cloned h. contortus alpha- and beta-tubulin genes were used ... | 1990 | 1981249 |
| specific interaction of benzimidazole anthelmintics with tubulin from developing stages of thiabendazole-susceptible and -resistant haemonchus contortus. | the low- and high-affinity binding of tritiated benzimidazole anthelmintics (mebendazole and oxibendazole) to tubulin-containing supernatants derived from unembryonated eggs, third stage larvae or adult worms of thiabendazole-susceptible and -resistant strains of haemonchus contortus were examined and compared. the displacement of these radioligands by unlabelled benzimidazoles (mebendazole, fenbendazole, thiabendazole and oxibendazole) also was examined. the binding affinity, k alpha, and maxim ... | 1991 | 1986746 |
| utility of a haemonchus contortus/jird (meriones unguiculatus) model for studying resistance to levamisole. | trichostrongylid nematodes of sheep commonly are identified as exhibiting resistance to levamisole. in vitro assays have been developed to study levamisole resistance for haemonchus contortus, but no in vivo model has been identified for this species. to determine the utility of a h. contortus/jird (meriones unguiculatus) model for examining levamisole resistance, immunosuppressed jirds were inoculated with approximately 1,000 exsheathed infective larvae of h. contortus (resistant or susceptible ... | 1991 | 1992099 |
| fecundity of anthelmintic resistant adult haemonchus contortus after exposure to ivermectin or benzimidazoles in vivo. | a strain of haemonchus contortus resistant to the benzimidazoles, ivermectin and salicylanilides was used to study the effect of exposure to ivermectin or oxfendazole on the number of eggs produced by adult female parasites. after anthelmintic administration there was a reduction in the faecal egg count of the infected lambs. ivermectin caused a reduction in the number of eggs within adult parasites for up to 72 hours but this returned to higher than pre-treatment levels at 168 hours after treat ... | 1991 | 2034909 |
| secretion and excretion of endogenously synthesized lipids by adult haemonchus contortus in vitro. | results of the incorporation of carbon from 14c-glycerol into total, polar and nonpolar lipids in haemonchus contortus (nematoda: trichostrongylidae) reveal that the radioactivity lost into the medium as lipids decreased during the first 3 h of incubation. this was followed by a drastic increase during the 4th h. again, there was a decline by 75% during the 5th h. however, there was a slight increase in the nonpolar lipids during the 5th h. | 1991 | 2050989 |
| effect of development of resistance to benzimidazoles, salicylanilides and ivermectin on the pathogenicity and survival of haemonchus contortus. | two groups of six lambs were infected either with an anthelmintic-susceptible strain of haemonchus contortus or with a strain resistant to benzimidazoles, ivermectin and salicylanilides. the pathogenicity of the two strains of parasite was compared by monitoring the development of anaemia, changes in plasma proteins and abomasal damage in the two groups of lambs. there were no significant differences between the groups, suggesting that the development of resistance to several anthelmintics did n ... | 1991 | 2063534 |
| effects of cholinergic drugs on longitudinal contraction in levamisole-susceptible and -resistant haemonchus contortus. | a novel force transducer was used to measure the effects of cholinergic agonists on longitudinal contraction in haemonchus contortus. drugs were applied to whole worms or injected via a cannula in the pseudocoelomic cavity. a number of agonists, including nicotine and the anthelmintics m-aminolevamisole, levamisole and morantel, caused contractions in whole worms. four- to 25-fold increases in concentration of the active compounds were required to cause contractions in each of two levamisole-res ... | 1991 | 1757196 |
| interaction of parasitism and nutrition and their effects on production and clinical parameters in goats. | weaned wether goats (n = 144) approximately 6 months of age were placed in a 2 x 3 factorial design experiment for 5 months to test the main effects and interaction of two levels of nutrition (growth + maintenance, nut1; twice growth + maintenance, nut2) and three levels of haemonchus contortus burden (0, 500 and 2000 larvae administered every 2 weeks: w0, w500 w2000, respectively) on weight, feed intake, level of infection and packed cell volume (pcv). the rationale for the experimental design ... | 1991 | 1763494 |
| detection of resistance to ivermectin in haemonchus contortus. | infective, third-stage (l3) larvae of haemonchus contortus isolates resistant to ivermectin (ivm) show a decreased sensitivity to ivm-induced paralysis in vitro. the inhibition of larval motility by ivm can be detected in l3 larvae incubated in the dark on an agar matrix containing ivm, by the failure of affected larvae to move when stimulated by exposure to light. optimally, avermectin (avm) potency is quantified after three cycles, each involving storage in the dark for 24 h followed by a brie ... | 1991 | 1774112 |
| infection of goats with haemonchus contortus and trichostrongylus colubriformis: histopathology and ph changes. | two groups of goats were experimentally infected with haemonchus contortus and trichostrongylus colubriformis, and killed at various days after infection (dai). the percentage of worms that established in the abomasum and the small intestine was low. at necropsy, abomasums from infected goats had thickened walls and oedematous folds. at 7 dai there was an initial infiltration of eosinophils and some neutrophils which tend to increase with age of infection. the mean ph of the abomasum in goats in ... | 1991 | 1777801 |
| ultrastructural changes associated with exsheathment of infective juveniles of haemonchus contortus. | ultrastructural changes associated with exsheathment of the infective juveniles of haemonchus contortus are described. hyaline ring formation occurs associated with annulations 10 and 20 and consists of the dissolution of the basal zone and the inner electron-dense layer resulting in the rupture of the sheath. these changes are consistent with the action of a protease-exsheathing enzyme. there is a significant reduction associated with exsheathment in the size of the excretory cells and the numb ... | 1991 | 1780179 |
| disposition of oxfendazole in goats and efficacy compared with sheep. | the disposition of intraruminally administered oxfendazole (ofz) in goats was studied at 5, 10 and 20 mg kg-1. the area under the plasma concentration with time curve (auc) increased with increasing dose but at a declining rate. auc was lower after intra-abomasal compared with intraruminal administration. ofz was less effective against drug resistant trichostrongylus colubriformis in goats than in sheep but was of similar efficacy against drug resistant haemonchus contortus in both host species. ... | 1991 | 1780578 |
| effect of weaning on antibody responses and nematode parasitism in merino lambs. | lambs weaned at eight weeks old were compared with control lambs which remained with their dams; both groups grazed the same pasture. weaning significantly reduced the growth rate, control lambs being, on average, 6 kg heavier than weaned lambs at 15 weeks old. when contamination of pasture with larval parasites was light, both groups of lambs suffered only modest parasitic infections. when lambs were experimentally infected with 5000 haemonchus contortus and 10,000 trichostrongylus colubriformi ... | 1991 | 1788476 |
| blood gastrin and pepsinogen responses of native village goats in malaysia to infection with haemonchus contortus. | blood gastrin and pepsinogen responses of native village goats in malaysia to a single dose of 10,500 infective haemonchus contortus larvae were investigated. both blood values were significantly elevated within a week of infection and exhibited a highly significant correlation during the study. the magnitude of the blood gastrin response was, however, significantly greater than that of pepsinogen during the period that both blood values were elevated. it is suggested that blood gastrin assay ma ... | 1991 | 1796870 |
| cloning of a cdna encoding phosphofructokinase from haemonchus contortus. | phosphofructokinase (pfk), the key regulatory enzyme in glycolysis, has been cloned from the pathogenic parasitic nematode haemonchus contortus by functional complementation in escherichia coli. an e. coli strain deleted for both pfk loci (strain df1020) was transformed with plasmid dna from a lambda zap ii h. contortus cdna library. two out of 3 x 10(7) transformants were able to grow on minimal medium with mannitol as the sole carbon source. a plasmid, ppfk, containing a 2.7-kb insert, was iso ... | 1991 | 1838137 |
| serum igg response of manchego lambs to infections with haemonchus contortus and preliminary characterization of adult antigens. | manchego lambs (16-18 weeks old) were infected with 2500 infective larvae (l3) of haemonchus contortus and challenged 2 months later with 5000 l3. the serum igg anti-haemonchus response was estimated by enzyme-linked immunosorbent assay (elisa) using soluble proteins from adults and l3. previously infected manchego lambs failed to mount a protective immune response against challenge, at least as assessed by faecal egg counts and pre-patency periods. primary infection did not provoke any rise in ... | 1991 | 1858283 |
| changes in liveweight gain and blood constituents in experimental infection of goats with a goat-derived compared with a sheep-derived strain of haemonchus contortus. | two groups of goats were experimentally infected with two different strains of haemonchus contortus and compared with the controls. group a animals were infected with a goat-derived strain (gds) while group b animals were infected with a sheep-derived strain (sds). changes in the liveweights and some blood constitutents between the two infected groups were compared. the pathogenic effects of the gds larvae were generally more serious when compared with those of the sds larvae. | 1991 | 1858284 |
| concurrent infections with the ruminant nematodes haemonchus contortus and trichostrongylus colubriformis in jirds, meriones unguiculatus, and use of this model for anthelmintic studies. | haemonchus contortus- and trichostrongylus colubriformis-infected jirds (meriones unguiculatus) are useful for anthelmintic studies. with concurrent infections of these parasites established in the jird, questions of not only anthelmintic activity, but to some extent spectrum, could be assessed in a single model system. this report outlines a model using immunosuppressed (0.02% hydrocortisone in feed) jirds concurrently infected with h. contortus and t. colubriformis. immunosuppressed jirds were ... | 1991 | 1865271 |
| interaction of benzimidazole anthelmintics with haemonchus contortus tubulin: binding affinity and anthelmintic efficacy. | the ability of various benzimidazoles (bzs) to bind tubulin under different conditions was assessed by determining their ic50 values (the concentration of unlabeled drug required to inhibit 50% of the labeled drug binding), ka (the apparent equilibrium association constant) and bmax (the maximum binding at infinite [bz] = [drug-receptor]). the ability of unlabeled benzimidazoles--fenbendazole, mebendazole (mbz), oxibendazole (obz), albendazole (abz), rycobendazole (albendazole sulfoxide, abzso), ... | 1991 | 1889474 |
| fecundity of gastrointestinal trichostrongylid nematodes of sheep in the field. | twenty-two dorset rambouillet lambs were moved to contaminated pasture on apr 1, 1987. at regular intervals thereafter, pairs of lambs were withdrawn and euthanatized. gastrointestinal parasites in the abomasum, small intestine, cecum, and large intestine were removed and counted. the last pair of lambs was euthanatized 8 months after original placement on the contaminated pasture. fecal samples were taken at 3- to 4-week intervals throughout the grazing season and the fecal egg counts were used ... | 1991 | 1892277 |
| periparturient rise in faecal nematode egg counts in west african dwarf sheep in southern ghana in the absence of arrested strongyle larvae. | the nematode egg output of two groups of ewes, a pregnant test group (2-3 years of age) mated between march and april and a non-pregnant control group (5-6 years of age) was followed. the worm burdens acquired by worm-free 'tracer' lambs were also followed on the same pasture from march 1988 to february 1989. there was a significant difference (p less than 0.05) in the magnitude of the egg output in the test group compared with the control group. in the test ewes, an initial rise in egg producti ... | 1991 | 1897121 |
| post natal ontogeny of immunological responsiveness in merino sheep. | sheep in five age groups (two weeks, 10 weeks, 18 weeks, six months and four years old) were immunised systemically, twice, with ovalbumin or brucella abortus (live or killed) and antibody responses in blood were measured. the animals were also infected with the nematode parasites trichostrongylus colubriformis and haemonchus contortus and faecal egg counts and serum antibody responses to larval antigens were measured. the experiments were designed so that, as far as possible, the effect of age ... | 1991 | 1910202 |
| protective immunity to a blood-feeding nematode (haemonchus contortus) induced by parasite gut antigens. | to determine the ability of gut antigens to induce a protective immune response against blood-feeding nematodes, isolated gut antigens were used to immunize goats against haemonchus contortus. immunization-induced antibody responses recognized parasite gut antigens which were associated predominantly with the microvillous membrane region of the parasite gut. antibody from immune serum also recognized seven predominant gut proteins on a western blot (immunoblot). several of these proteins appeare ... | 1991 | 1937800 |
| effectiveness of clean grazing strategies in controlling haemonchus contortus infections in sheep in the united kingdom. | the effectiveness of clean grazing systems for controlling the sheep abomasal parasite haemonchus contortus under experimental conditions was monitored for a grazing season in ewes and lambs carrying either benzimidazole-susceptible or resistant populations of the parasite. both preventive and evasive strategies failed to give effective control of h contortus. lambs grazing with ewes that had received no anthelmintic showed clinical signs of haemonchosis by early july. lambs from ewes dosed with ... | 1991 | 1949535 |
| synthesis and biological activity of a series of diaryl-substituted alpha-cyano-beta-hydroxypropenamides, a new class of anthelmintic agents. | a series of alpha-cyano-beta-hydroxypropenamides was prepared and tested for anthelmintic activity. alpha-cyano-beta-hydroxy-n-[4- (trifluoromethyl)phenyl]-3-[4-(trifluoromethyl)phenyl]propenamide (1) showed good activity against the nematode nematospirodes dubius in a mixed parasite infection in mice; several of the analogues were also effective against the cestode hymenolepis nana. in sheep trials, 1 caused 100% reduction of the hematophagous nematode haemonchus contortus after a single dose o ... | 1991 | 1956049 |
| non-specific resistance of sheep against haemonchus contortus with freund's complete adjuvant. | six groups of four ovines each were injected intraperitoneally with freund's complete adjuvant (fca), at various times before, during, or after infection with 10 000 larvae (l3) of haemonchus contortus per sheep. animals in groups a and b received fca on days 14 and 7, respectively, before infection. ovines in group c were treated with fca on the same day of infection; while sheep in groups d, e, and f were injected with the adjuvant on days 7, 14, and 21, respectively, after infection. signific ... | 1991 | 1956702 |
| effectiveness of strategic anthelmintic dosing in controlling haemonchus contortus infections in sheep in the united kingdom. | the strategic use of anthelmintics in the control of infections of haemonchus contortus in ewes and lambs, was investigated in a series of paddock trials. the levels of infection and clinical signs associated with the presence of either benzimidazole-resistant or benzimidazole-susceptible strains of h contortus in lambs were controlled by regular drenching with levamisole or mebendazole, respectively, or by the strategic use of closantel in combination with mebendazole. in the latter case, contr ... | 1991 | 1957469 |
| efficacy of some anthelmintics on an ivermectin-resistant strain of haemonchus contortus in sheep. | following evidence of reduced efficacy of ivermectin in a field population of haemonchus contortus in brazil, this strain of the parasite was submitted to a controlled anthelmintic test. eighty worm-free lambs were randomly split into two groups of 40. each lamb in the first group was infected with 5000 third stage larvae (l3) of the ivermectin-resistant strain; the remaining 40 lambs were each infected with 5000 l3 of a h. contortus strain of known susceptibility to the major groups of anthelmi ... | 1991 | 1957487 |
| beta-tubulin and benzimidazole resistance in the sheep nematode haemonchus contortus. | we have compared benzimidazole (bz) susceptible (s) and resistant (r) strains of haemonchus contortus from sheep by two-dimensional polyacrylamide gel electrophoresis (2-d page), western blotting and elisa techniques. the s strain bound more drug per mg protein than the r strain. bz binding could be resolved into high-affinity and low-affinity binding. low-affinity binding in parasite preparations devoid of tubulin was observed, but high-affinity binding occurred only in preparations containing ... | 1991 | 1857382 |
| [development and survival of haemonchus contortus isolated from sheep on a pasture at bunia (itiri, zaire)]. | development and survival of haemonchus contortus larvae were studied from december 1987 to november 1988 during three different periods (dry season, first and second rainy seasons) on an experimentally infected pasture at bunia (ituri, zaïre). whatever the season, eggs developed into infective larvae within six days and the largest number of larvae on the herbage occurred between the 12th and the 18th day post deposition. however, the two rainy seasons were the most favourable for transmission b ... | 1991 | 1818364 |
| production and characterization of monoclonal antibodies against excretory-secretory products of fasciola hepatica. | four monoclonal antibodies (mabs) (9.49, 24.27, 46.71 and 179.57) were produced against fasciola hepatica excretory-secretory products. isotype analysis revealed the antibodies to be igm, igg3, igg1, and igm. in immunoblot assays, the mabs recognized different antigenic polypeptides migrating between 29 and 180 kda. specificity of the mabs was evaluated by elisa against antigens of fascioloides magna, anoplocephala magna, stichorchis subtriquetrus, haemonchus contortus, sheep liver extract (sle) ... | 1991 | 1788930 |
| a study of the mortality and fecundity of haemonchus contortus in sheep following experimental infections. | the regulation of the fecundity and mortality of h. contortus in sheep was examined using a series of mathematical models. six-month-old dorset crossbred lambs were infected once only with various doses of infective h. contortus larvae (500-20,000 larvae). parasite mortality was found to be an increasing linear function of the magnitude of the initial infection over the range of doses examined. parasite fecundity was found to remain constant over the intensity and duration of the infection. the ... | 1991 | 1774120 |
| purified glutathione s-transferases from parasites as candidate protective antigens. | glutathione s-transferase (gst) activity was detected in larvae of the australian sheep blowfly lucilia cuprina, and in the nematode haemonchus contortus. a specific inhibitor of the enzyme was shown to affect survival of both species of parasite in vitro. gst from both parasites has been purified and partially characterized. antisera raised to the purified enzymes were shown to inhibit the enzyme activity in vitro. however, the antisera had no effect on the survival of either parasite. | 1991 | 1774119 |
| effects of time of day, season and stratum on haemonchus contortus and haemonchus placei third-stage larvae on irrigated pasture. | the effect of time of day, season and stratum of herbage and soil on the availability of haemonchus contortus and haemonchus placei third-stage larvae (l3) on pasture was assessed. feces from infected calves and lambs were placed on pasture plots and samples of upper herbage, lower herbage, mat and soil were collected at five intervals per day throughout the daylight hours on 18 sample days over 12 months. using recovery rate factors derived from a preliminary investigation on the efficacy of la ... | 1991 | 1763493 |
| immunity to haemonchus contortus and the cellular response to helminth antigens in the mammary gland of non-lactating sheep. | cellular exudates induced by infusion with helminth antigens were examined in non-lactating mammary glands of ewes immune to infection with the abomasal nematode, haemonchus contortus. secondary immunological responsiveness was expressed in two ways. firstly, antigens from adult h. contortus elicited larger eosinophil-rich cellular exudates in immune compared to non-immune ewes. in this situation, secondary responsiveness in the mammary gland must have been generated through abomasal infection w ... | 1991 | 1757191 |
| local eradication of haemonchus contortus using closantel. | 1991 | 1755790 | |
| a possible role of caesium radiations in the control of propagation of hookworm. | faeces charcoal mixtures containing eggs of sheep hookworm, haemonchus contortus were exposed to caesium radiations (23 r to 1656 r) from 1st to 7th day of incubation. each plate was exposed only once. a dose related inhibition of transformation of eggs to infective larvae was observed. the maximum effect was observed on 2nd day of incubation. the radiation has maximum effect on the 1st stage larvae followed by 2nd stage. the 3rd stage or ineffective larvae are relatively resistant to the effect ... | 1991 | 1743750 |
| effects of plumbagin on development of the parasitic nematodes haemonchus contortus and ascaris suum. | 1. plumbagin (5-hydroxy,2-methyl-1,4-napthoquinone) inhibited the motility and survival of haemonchus contortus first-stage larvae (l1) with an ed50 of 1 microgram/ml, but was less effective in preventing the development of h. contortus to infective third-stage larvae in a faecal slurry assay. 2. of the structural analogs tested, plumbagin was the most potent in preventing development of l1 followed in decreasing order of potency by 1,4-naphthoquinone, 5-hydroxy-1,4-napthoquinone (juglone) and 1 ... | 1991 | 1687553 |
| [the threat of wide dissemination of anthelmintic resistance by veld ram performance testing units]. | a veld ram performance testing unit consists of an association of stud or commercial ram breeders, who compare the performance of selected rams under field conditions on common pastures. the best performers are subsequently auctioned at public sales. to date, at least 10 merino veld ram clubs have been established in various centres in south africa. a strain of haemonchus contortus, which was isolated from the pastures of one of these performance testing units, was found to be resistant to iverm ... | 1991 | 1770493 |
| protective studies in sheep immunized with cuticular collagen proteins and peptides of haemonchus contortus. | twenty-eight nonsibling sheep aged approximately 12 months and raised in a helminth-free environment were used in two protection studies. immunizations were conducted by two intramuscular injections 30 days apart with a synthetic 18aa cuticle collagen peptide and native cuticle collagens derived from the third- and fourth-stage larvae of haemonchus contortus. ten days following the last immunization, the sheep were each given 500 infective h. contortus larvae per day for five consecutive days by ... | 1991 | 1852473 |
| biochemical characterisation of the enzyme responsible for "activated l-serine sulphydrase" activity in nematodes. | the biochemical properties of the enzyme responsible for nematode "activated l-serine sulphydrase" activity (l-cysteine + r-sh----cysteine thioether + h2s) have been investigated using primarily the gastro-intestinal nematodes nippostrongylus brasiliensis and haemonchus contortus. the activated l-serine sulphydrase enzyme was found to be cytosolic in origin and exhibited maximal activity at ph 9.0. enzyme activity was widely distributed amongst the major tissues of adult female ascaris suum but ... | 1992 | 1740180 |
| identification of a novel brugia pahangi beta-tubulin gene (beta 2) and a 22-nucleotide spliced leader sequence on beta 1-tubulin mrna. | we have examined the expression of beta-tubulin genes in the parasitic nematode, brugia pahangi. a genomic library was constructed and screened by hybridization with a haemonchus contortus beta-tubulin cdna fragment which recognizes several b. pahangi beta-tubulin sequences, including sequences which correspond to the previously characterized beta 1-tubulin gene. the b. pahangi beta 2-tubulin gene was isolated by selecting clones which hybridize to the h. contortus beta-tubulin gene but which do ... | 1992 | 1741015 |
| cloning of a cdna encoding phosphoenolpyruvate carboxykinase from haemonchus contortus. | biochemical and metabolic data have led to the conclusion that the enzyme phosphoenolpyruvate carboxykinase (pepck; ec 4.1.1.32) contributes to a critical point of divergence in energy conservation pathways between mammals and nematodes. to facilitate the determination of the molecular basis for host vs parasite differences in pepck, we have cloned a cdna encoding this enzyme from a parasitic nematode of ruminants, haemonchus contortus. h. contortus pepck was cloned by functional complementation ... | 1992 | 1741016 |
| survey for drug-resistant gastrointestinal nematodes in 13 commercial sheep flocks. | the prevalence of drug-resistant ovine parasites in the united states has not been widely reported. thirteen flocks, typical of commercial sheep production units, were selected for survey. four anthelmintics (fenbendazole, ivermectin, pyrantel pamoate, and levamisole) were tested for their ability to reduce herd mean pretreatment fecal egg count. if a properly dosed and administered drug failed to reduce herd mean pretreatment fecal egg count by 80%, it was considered ineffective in that flock, ... | 1992 | 1644650 |
| systemic immunization of sheep with surface antigens from haemonchus contortus larvae. | sheep immunized systemically with a surface extract from third-stage h. contortus larvae showed high serum antibody reactivity against surface antigens and whole, viable larvae. after a first infection, no significant difference was found between the mean egg counts of the vaccinates and controls although most vaccinated sheep seemed to show an increased susceptibility to infection. the local abomasal response was stimulated by giving both vaccinated and control sheep a large, abbreviated infect ... | 1992 | 1644531 |
| parasitological and immunological responses of genetically resistant merino sheep on pastures contaminated with parasitic nematodes. | one hundred and twenty lambs were grazed continuously from weaning until 9 months of age on 12 plots contaminated with larvae of three nematode species (haemonchus contortus, trichostrongylus colubriformis and ostertagia circumcincta). the lambs were sired by either a genetically resistant ram or susceptible rams (determined by the response of previous progeny to artificial h. contortus infection). half the resistant and half the susceptible lambs were given strategic anthelmintic treatment and ... | 1992 | 1644517 |
| the mortality and fecundity of haemonchus contortus in parasite-naive and parasite-exposed sheep following single experimental infections. | parasite-exposed lambs and their parasite-naive controls were experimentally infected once only with 30,000 h. contortus larvae at 3, 9, 12, and 20 weeks following termination of a moderate immunizing infection of 30,000 h. contortus larvae. previously exposed lambs, challenged at 3 weeks, had a significant reduction in the total h. contortus worm burden as compared to parasite-naive controls. no difference in the total h. contortus worm burden was found between parasite-exposed or parasite-naiv ... | 1992 | 1639567 |
| a microlarval development assay for the detection of anthelmintic resistance in sheep nematodes. | a microlarval development test for the detection of anthelmintic resistance in nematodes is described. haemonchus contortus, teladorsagia circumcincta and trichostrongylus colubriformis eggs were cultured to third stage larvae in the presence of earle's balanced salt solution, yeast extract and bacteria in a total volume of 150 microliters. good dose-response data were obtained with thiabendazole, levamisole, pyrantel tartrate and ivermectin allowing the determination of the 50 per cent lethal c ... | 1992 | 1621342 |
| induction of tissue eosinophilia by platelet-activating factor in merino sheep. | a study was undertaken on the capacity of platelet-activating factor (paf) to induce eosinophil accumulation in the mammary glands of non-lactating sheep. platelet-activating factor induced dose-dependent accumulation of eosinophils in mammary exudates 24 h after infusion. infection, by intraruminal injection of 20,000 infective trichostrongylus colubriformis larvae, did not modify the responsiveness of outbred sheep to intramammary infusion of paf. mature ewes from high and low responder lines ... | 1992 | 1604802 |
| growth and development of haemonchus contortus in jirds, meriones unguiculatus. | growth and development of haemonchus contortus were examined in jirds and were compared to these processes in lambs. number, sex, size, and stage of development were determined for worms recovered at necropsy at various times postinoculation (pi) from immunosuppressed jirds inoculated with approximately 1,000 exsheathed infective larvae (l3) of h. contortus. in addition, gastric tissue samples from jirds were examined histologically. parallel studies were done in lambs inoculated with approximat ... | 1992 | 1597794 |
| three beta-tubulin cdnas from the parasitic nematode haemonchus contortus. | experimental evidence indicates that tubulin is the site of action of the anthelmintic benzimidazoles. furthermore, certain residues of beta-tubulin seem to be critical for this mechanism. although the benzimidazoles selectively affect nematode vs. mammalian beta-tubulin, the molecular basis for this differential action is not known. to enhance our understanding of this phenomenon, and to provide the basis for investigating benzimidazole resistance in parasitic nematodes, we undertook the clonin ... | 1992 | 1741017 |
| humoral responses in rabbits immunized with two fractions of haemonchus contortus: the antigen specificity of such antibodies. | humoral responses were examined in rabbits immunized with either 28-40 kda (fraction 1) or a 19-24 kda (fraction 2) antigenic fraction from soluble antigens (sol l3 ag) from infective larvae (l3) of haemonchus contortus. these fractions were eluted from electrophoretically separated sol l3 ag. immunoblots revealed antibodies to fraction 1 (fr. 1) or fraction 2 (fr. 2) polypeptides as well as to several other molecular weight polypeptides of the sol l3 ag. the latter antibodies were shown by abso ... | 1992 | 1281589 |
| helminths of sheep and goats in desert areas of south-west mauritania (trarza). | faecal samples were obtained from sheep and goats before, during and after the rainy season at three locations in south-west mauritania. several animals were also necropsied at the same time. haemonchus contortus was the most prevalent worm. infection by digestive-tract strongyles and strongyloides papillosus was always very light (prevalence less than 20%). sheep were more heavily infected than goats but animals under 1 year of age were not infected by digestive-tract strongyles. it is likely t ... | 1992 | 1295205 |
| comparative neuromuscular blocking actions of levamisole and pyrantel-type anthelmintics on rat and gastrointestinal nematode somatic muscle. | the basis for the comparative toxicity to parasitic nematodes and their mammalian hosts of the anthelmintics levamisole, pyrantel, and several related analogs on somatic nicotinic cholinergic transmission was examined. measurements of muscle contractility and membrane potential were made using the isolated hemidiaphragm preparation of the rat and isolated axial muscle segments from the gastrointestinal nematode haemonchus contortus. pyrantel caused a dose- and time-dependent reduction of nerve-e ... | 1992 | 1310165 |
| histoenzymic effects of thiophenate and fenbendazole on the absorptive surfaces of haemonchus contortus. | in vitro alterations induced by a 10 micrograms/ml and 50 micrograms/ml dose each of thiophenate and fenbendazole on the absorptive surfaces of haemonchus contortus (nematoda: trichostrongylidae) were studied. the most significant changes were induced in the gut epithelium. alkaline phosphatase and adenosine triphosphatase activities were decreased, succinic dehydrogenase activity was increased, while acid phosphatase and glucose-6-phosphatase were completely lost from the intestinal epithelium ... | 1992 | 1335682 |
| the development and mortality of the free-living stages of haemonchus contortus in laboratory culture. | haemonchus contortus eggs were cultured in intact fecal pellets at various temperatures (5-35 degrees c) for 22 days. temperature and relative humidity were kept constant throughout the incubation period. nl larval development occurred at 5 degrees c; peak third-stage larval recovery occurred at 20 degrees c. egg mortality was an age-dependent phenomenon, whereas larval mortality remained constant irrespective of larval age. development was characterized by a minimum development time followed by ... | 1992 | 1399249 |
| response to ivermectin treatment of parasitic stages of haemonchus contortus resistant or susceptible to ivermectin. | two groups of 33 helminth-naive lambs were infected with 5,000 l3 of an ivermectin-resistant or -susceptible strain of haemonchus contortus (groups r and s). on days 6, 10, 16, and 21 postinfection, 5 animals from each group were chosen at random and orally treated with 0.2 mg/kg of ivermectin. on each occasion, 2 randomly selected lambs from each group were also killed to determine the number and stage of development of the worms present at the time of treatment. these necropsies revealed that ... | 1992 | 1403434 |
| the interaction of trypanosoma congolense and haemonchus contortus infections in trypanotolerant n'dama cattle. | the interactions between trypanosoma congolense and haemonchus contortus infections were studied in n'dama calves. a total of 38 n'dama bulls was divided into four groups and each group infected either with h. contortus 1 week after infection with t. congolense or with t. congolense 4 weeks after infection with h. contortus, or with either infection singly. parasitological (faecal egg counts, parasitaemia), haematological (packed cell volume, white blood cell counts, albumin) and clinical parame ... | 1992 | 1413448 |
| multiple anthelmintic resistance in a field strain of haemonchus contortus in goats. | 1992 | 1413479 | |
| lymphocyte reactivity to antigens of haemonchus contortus in antigen-inoculated and h contortus-naive lambs. | lambs were inoculated during either fetal or early neonatal life with antigens of haemonchus contortus (hcag) third-stage larvae, or ovalbumin (ova), or were left untreated. by the time lambs were 4 weeks old, blood lymphocytes from all of them responded to hcag. this was evident in all lambs, regardless of the previous inoculation regimen, although higher response was seen in hcag-inoculated lambs, compared with naive lambs. only lambs inoculated with ova had ova-specific lymphocyte activity. i ... | 1992 | 1416379 |
| a preliminary study of the effect of microclimate on third-stage larvae of haemonchus contortus and haemonchus placei on irrigated pasture. | assessments were made on the influence of several microclimatic variables on the availability of third-stage larvae of haemonchus contortus and haemonchus placei on four strata of irrigated kikuyu pasture. three replicates of these pasture samples were collected on 18 sample days over 12 months and the log10 mean counts of the larvae recovered were analysed by a step-wise regression model. predictors for the log counts of the four strata for the two nematode species included relative humidity, i ... | 1992 | 1428508 |
| the influence of challenge dose, duration of immunity, or steroid treatment on mucosal mast cells and on the distribution of sheep mast cell proteinase in haemonchus-infected sheep. | the distribution of granule-specific sheep mast cell proteinase (smcp), was assayed by immunocytochemistry and quantified by immunoassay in sheep immune to haemonchus contortus. repeated infection with haemonchus larvae over 10-12 weeks induced a pronounced mucosal mastocytosis, including intraepithelial globule leukocytes (gl), which, 7 days after ceasing this dosing regime, was associated with the inability of incoming larvae to establish within the abomasal mucosa. loss of this resistance, du ... | 1992 | 1437235 |
| isoenzyme analysis of haemonchus contortus resistant or susceptible to ivermectin. | three different strains of haemonchus contortus (susceptible to ivermectin, s-ivm; selected for resistance to ivermectin, r-ivm; a multiple resistant strain, i.e. resistant to benzimidazole and ivermectin, r-ivm/sa) were examined for isoenzyme variation by starch gel electrophoresis. using stains for seven enzymes separated in five different buffer systems, no differences in the electrophoretic mobility could be detected between any of the strains. results demonstrate a low level of enzyme varia ... | 1992 | 1441194 |
| characterization of the eggshell of haemonchus contortus--i. structural components. | 1. by transmission electron microscopy, the eggshell of haemonchus contortus was seen to be similar to previously studied nematodes, with an outer vitelline layer bounded by a trilaminate membrane, a broad medial region, containing chitin, and an electron dense basal region, containing lipid and protein. 2. exposure of haemonchus contortus eggs to proteases resulted in disruption of the shell with removal of components of the outer, medial and basal regions. exposure to chitinase depleted fibril ... | 1992 | 1458842 |
| the kinetics of mebendazole binding to haemonchus contortus tubulin. | the kinetics of the binding of mebendazole (mbz) to tubulin from the third-stage (l3) larvae of the parasitic nematode, haemonchus contortus, have been characterized. in partially purified preparations, the association of [3h]mbz to nematode tubulin was rapid, k1 = (2.6 +/- 0.3) x 10(5) m-1 min-1, but dissociation was slow, k-1 = (1.58 +/- 0.02) x 10(-3) min-1. the affinity constant (k(a)) for the interaction, determined by the ratio k1/k-1, was (1.6 +/- 0.2) x 10(8) m-1. similar results were ob ... | 1992 | 1459788 |
| selection of merino sheep for increased and decreased resistance to haemonchus contortus: peri-parturient effects on faecal egg counts. | peri-parturient worm egg counts were compared in 395 merino ewes bred for either increased (irh) or decreased (drh) resistance to haemonchus contortus, or from an unselected control flock (ch). following a 10 month period with no anthelmintic treatment, a rise in egg counts began about 4 weeks before parturition and continued into lactation. at all stages, egg counts were significantly lower in irh ewes, even those failing to conceive. before lambing, irh ewes averaged 263 epg, compared with 111 ... | 1992 | 1459789 |
| interaction of parasitism and nutrition in goats: effects on haematological parameters, correlations, and other statistical associations. | weaned wether goats (n = 144) approximately 6 months of age were placed in a 2 x 3 factorial experiment to test the effects and interaction of two levels of nutrition (growth+maintenance, nut1; and twice growth+maintenance, nut2) and three levels of haemonchus contortus burden (0, 500, and 2000 larvae administered every 2 weeks; w0, w500, and w2000, respectively) on packed cell volume, red blood cell count, total serum protein and leukocytes. the statistical analysis revealed clear and proportio ... | 1992 | 1466129 |
| immune response of clun forest sheep to vaccination with membrane glycoproteins from haemonchus contortus. | clun forest lambs were injected with a fraction containing integral membrane glycoproteins derived from the intestinal microvilli of haemonchus contortus in two equal doses of 0.5, 5, 50 or 500 micrograms protein and then challenged with 10,000 infective larvae. the time-course of serum specific antibody responses were determined. compared to the adjuvant control group, the animals injected with 1000 micrograms protein were better than 84% protected and those injected with 100 micrograms, better ... | 1992 | 1470484 |
| isolation of putative cysteine protease genes of ostertagia ostertagi. | recombinant phage containing putative ostertagia ostertagi cysteine protease genes have been isolated from a lambda embl-3:genomic dna library using a haemonchus contortus cathepsin b-like cysteine protease cdna as hybridization probe. restriction enzyme maps of the phages suggest that they identify at least 3 genes, 2 of which appear to be linked in tandem. the complete nucleotide sequence of one gene, cp-1, was determined. the cp-1 gene appears to be organized into 12 exons than span 4.5 kb of ... | 1992 | 1475000 |
| cloning of a cdna encoding alpha-tubulin from haemonchus contortus. | 1992 | 1484557 | |
| comparison of an indirect haemagglutination assay and an elisa for diagnosing fasciola hepatica in experimentally and naturally infected sheep. | an enzyme-linked immunosorbent assay (elisa) with somatic (s) or excretory-secretory antigens (es) was compared with an indirect haemagglutination assay (iha) for ability to detect antibodies against fasciola hepatica in sheep. the specificity of both assays was determined by testing sera collected from sheep experimentally or naturally mono-infected with fasciola hepatica, haemonchus contortus, ostertagia circumcincta, cooperia curticei, taenia ovis, eimeria spp., trichostrongylus vitrinus, tri ... | 1992 | 1485406 |
| haemonchus contortus resistance to ivermectin and netobimin in brazilian sheep. | suffolk, texel, hampshire down and ile de france sheep from the municipalities of porto amazonas, piraquara and araucaria in the state of paraná, and bagé in the state of rio grande do sul were brought to sobral, state of ceará, to be used in a cross-breeding project. on arrival they had clinical signs of nematode parasitosis, and one suffolk female died. the animals were treated orally with ivermectin (0.2 mg kg-1) and fifteen days later with netobimin (20.0 mg kg-1). neither drug reduced the e ... | 1992 | 1485411 |
| gastrointestinal helminths and lungworms of french dairy goats: prevalence and geographical distribution in poitou-charentes. | a study was conducted on 81 dairy-goat farms in western france. faecal samples were collected once and 31 culled goats were necropsied in order to assess their gastrointestinal and respiratory helminth species, their prevalences and the intensities of infection as well as their geographical distribution in six subregions of the surveyed area. fifteen species of helminth were recovered. the most frequent were muellerius capillaris, trichostrongylus colubriformis and teladorsagia circumcincta with ... | 1992 | 1494857 |
| evaluation of ivermectin against experimental infections of haemonchus contortus and trichostrongylus colubriformis in goats. | fourteen nematode parasite-naïve kids were given a mixed larval inoculum (approximately 17,250 infective larvae) via stomach tube. twenty-two days after infection, the kids were randomly assigned to control and treatment groups of seven animals each. mean eggs per gram for control and treatment groups were 4304 and 5315, respectively. kids in the treatment group were given ivermectin (0.2 mg kg-1) administered by subcutaneous injection. at necropsy, the mean numbers of haemonchus contortus and t ... | 1992 | 1496785 |
| fibrinogen-degrading proteins from haemonchus contortus used to vaccinate sheep. | sixteen nonsibling sheep, approximately 12 months old, that were raised in a helminth-free environment, were used for 2 protection studies 6 months apart. sheep were vaccinated weekly for 5 weeks by im injection of fibrinogen-degrading proteins derived from the intestinal tract of adult haemonchus contortus. ten days after the last vaccination, sheep were given 2,500 infective h contortus larvae by intraruminal injection. vaccinated sheep produced specific antibodies, and were protected from the ... | 1992 | 1497200 |
| anthelmintic activity of dioxapyrrolomycin. | dioxapyrrolomycin, pyrrolomycin c, pyrrolomycin d, and piericidin c2 produced by uc 11065 were evaluated as anthelmintics. assays used to examine these compounds included effects on the free-living nematode caenorhabditis elegans, ability to clear target nematodes (haemonchus contortus and trichostrongylus colubriformis) from jirds, and clearance of haemonchus contortus from lambs. a crude extract of uc 11065 containing dioxapyrrolomycin, pyrrolomycin c, pyrrolomycin d, and piericidin c2 was act ... | 1992 | 1500366 |
| resistance of st. croix lambs to haemonchus contortus in experimentally and naturally acquired infections. | parasitological and immunological parameters of experimental or naturally acquired infections with haemonchus contortus were compared in st. croix and dorset lambs. in experimental infections, st. croix lambs developed significantly greater levels of resistance to h. contortus, following primary exposure, as compared with dorset lambs. this resistance was influenced both by age and by prior exposure to parasites. in grazing experiments on h. contortus-infected pasture, st. croix lambs shed signi ... | 1992 | 1502784 |