| [anthelmintic resistance in sheep nematodes in the netherlands]. | the prevalence of anthelmintic resistant nematodes in sheep was investigated in 1994 with a faecal egg count reduction test (fecrt) and an egg hatch assay (eha) on 71 farms in the netherlands. a benzimidazole (oxfendazole) was tested on 70 farms, ivermectin on 51 farms, and levamisole on 35 farms. based on the fecrt benzimidazole resistance was present on 56 farms, 2 were suspected, on 9 no resistance was observed, while 3 farms could not be tested due to a too low egg output before treatment. n ... | 1995 | 7900149 |
| efficacy of oral moxidectin against benzimidazole-resistant isolates of gastrointestinal nematodes in sheep. | the efficacy of orally administered moxidectin was determined against four benzimidazole-resistant nematode isolates. at the start of the trial, 30 lambs were each infected experimentally with 20,000 third stage larvae (5000 haemonchus contortus, 7000 teladorsagia circumcincta, 3000 trichostrongylus colubriformis and 5000 cooperia curticei); 28 days later they were allocated randomly to three groups of 10: one untreated group, one group treated orally with fenbendazole (5 mg/kg bodyweight) and o ... | 1995 | 7900256 |
| a search for associations between major histocompatibility complex restriction fragment length polymorphism bands and resistance to haemonchus contortus infection in sheep. | polymorphic bands were detected within the dqb and drb regions of the ovine major histocompatibility complex by probing taqi digested dna from three large sheep half-sib families derived from a highly resistant ram. all animals were phenotypically assessed for haemonchus contortus resistance by faecal egg counts and associations with rflp bands and haplotypes were estimated using mixed model, best linear unbiased prediction statistical methods. although the highly resistant sire was homozygous a ... | 1993 | 7902040 |
| haemonchus contortus: the role of two beta-tubulin gene subfamilies in the resistance to benzimidazole anthelmintics. | the role of beta-tubulin genes in benzimidazole (bz) resistance was investigated using one susceptible (s) and two resistant (rt and rc) strains of haemonchus contortus. the rt strain was isolated from the field on the basis of thiabendazole resistance. the rc strain was derived from the s strain by treatment with cambendazole. cdnas, derived from the s strain, encoding two isoforms of beta-tubulin (beta 12-16 and beta 8-9), alpha-tubulin and phosphofructokinase (pfk) were used as probes for sou ... | 1994 | 7910461 |
| benzimidazole resistance in haemonchus contortus is correlated with a conserved mutation at amino acid 200 in beta-tubulin isotype 1. | | 1994 | 7911975 |
| species identification of trichostrongyle nematodes by pcr-linked rflp. | restriction fragment length polymorphisms (rflp) of the second internal transcribed spacer (its-2) of ribosomal dna were examined for 6 species of ruminant nematodes; trichostrongylus colubriformis, t. axei, t. vitrinus, haemonchus contortus, teladorsagia circumcincta and cooperia oncophora. the its-2 of each species was amplified by pcr and restricted with the endonucleases drai, hinfi, rsai and vspi. using this approach, the 6 species could be distinguished. no intraspecific variation in rflp' ... | 1994 | 7913087 |
| cell-mediated immunity in merino lambs with genetic resistance to haemonchus contortus. | lymphocyte proliferation and skin hypersensitivity responses to parasite antigens were measured as indicators of cell-mediated immunity in genetically resistant and random-bred lambs following infection with haemonchus contortus. responses of pbmc to the mitogens pha, pwm and lps were also assessed to determine if infection was associated with suppression of general immune function. all lambs demonstrated significant antigen-specific lymphocyte proliferation prior to experimental infection. the ... | 1994 | 7928079 |
| purification and characterization of surface-associated proteins from adult haemonchus contortus. | extrinsic radioiodination experiments have shown that male and female adults of haemonchus contortus (bpl strain) express a stage-specific set of surface-associated proteins with apparent molecular mass values of 30, 58, 81, and 143 kda. a quantitatively different pattern of iodinated surface proteins is expressed by adults of the ppr strain of h. contortus, whereas the pattern of iodinated proteins expressed by haemonchus similis is qualitatively distinct (38, 68, and 121 kda). the 58-, 81-, an ... | 1994 | 7931909 |
| theoretical perspectives on anthelmintic drug discovery: interplay of transport kinetics, physicochemical properties, and in vitro activity of anthelmintic drugs. | this multidisciplinary study demonstrates the utility of the biophysical model approach to assess biological activity of anthelmintics in light of drug-delivery principles. the relationships between drug absorption and efficacy for a set of structurally disparate anthelmintics were determined in cultures of haemonchus contortus, a nematode that parasitizes the ruminant gastrointestinal tract. uptake, parameterized by the permeability coefficient, pe, was shown to occur by absorption across the c ... | 1994 | 7965664 |
| a middle-repetitive dna sequence element in the sheep parasitic nematode, trichostrongylus colubriformis. | a novel repetitive dna sequence in the sheep parasitic nematode trichostrongylus colubriformis was cloned and sequenced. a 1.1 kb repetitive sequence (tc15) which hybridized with dna from t. colubriformis but not with dna from two other parasitic nematodes, haemonchus contortus and ostertagia circumcincta, or sheep was further characterized. southern blot analysis showed that the repeat hybridized to a range of fragments in restriction digested t. colubriformis dna and existed in multiple copy n ... | 1994 | 7970890 |
| serum antibody responses of texel sheep experimentally infected with haemonchus contortus. | the primary and secondary serum antibody responses of texel sheep to infective larvae (l3) and adult worms of haemonchus contortus were studied. ten-month-old sheep were infected with 20,000 h contortus l3, treated with ivermectin seven weeks later and, after four weeks, reinfected with 10,000 l3 once a week for six weeks. faecal egg counts were significantly lower during the secondary infection than during the primary infection, but both infections induced antibody responses, as demonstrated by ... | 1994 | 7973095 |
| comparative efficacy of moxidectin and mebendazole against gastrointestinal nematodes in experimentally infected lambs. | a controlled trial was conducted to determine the anthelmintic efficacies of moxidectin and mebendazole. the compounds were administered orally at doses of 0.2 mg/kg bodyweight and 15.0 mg/kg bodyweight, respectively, to lambs infected experimentally with large numbers of gastrointestinal nematode larvae including a benzimidazole-resistant strain of haemonchus contortus. moxidectin was 100 per cent effective against adult h contortus, ostertagia species, trichostrongylus colubriformis, cooperia ... | 1994 | 7975106 |
| farm history and breeding management influences on the intensity and specific diversity of nematode infection of dairy goats. | sixteen dairy-goat farms were investigated in the centre-west of france for nematode infection. the intensity of infection was assessed by means of faecal egg counts and nematode counts at necropsy for digestive-tract nematodes and faecal larval counts for muellerius capillaris. the specific diversity and prevalence were estimated by worm counts of 28 necropsied culled goats. the history and breeding management were recorded by means of a questionnaire. specific diversity was estimated on two cu ... | 1994 | 7975117 |
| control of haemonchosis in malaysian goats with closantel. | the therapeutic and prophylactic effects of closantel on natural infections with haemonchus contortus were studied in goats in peninsular malaysia. closantel was highly effective against h. contortus, either at a subcutaneous (s.c.) injection of 5.0 mg kg-1 body weight (100%), or in an oral drench mixture with mebendazole at a dose of 10.0 mg kg-1 (99.2%), as indicated by faecal egg counts. h. contortus larvae were absent from faecal cultures for 5, 6 and 7 weeks following treatment with s.c. in ... | 1994 | 7975118 |
| cross antigenicity among ovine trichostrongyloidea. preliminary report. | a preliminary trial on the extent of cross-antigenicity among the sheep strongylids haemonchus contortus, trichostrongylus colubriformis, teladorsagia circumcincta and nematodirus battus in 2.5- to 4-month-old lambs has been carried out using elisa and western blotting (wb). cross antigenicity was tested using soluble extracts from adult and third stage larvae (l3) of h. contortus as antigenic source probed with sera from lambs with monospecific heterologous infections. there was cross-antigenic ... | 1994 | 7975119 |
| the heritability and specificity of responsiveness to infection with haemonchus contortus in sheep. | high responder (hr) and low responder (lr) lines of sheep of the hungarian merino breed were selected by using faecal egg counts (epg) as parameter of responsiveness after double artificial haemonchus contortus test infections. a total of 81 lambs born to assortative matings of hr rams with hr ewes and lr rams with lr ewes, as well as 28 control lambs from unselected parent sheep, were studied to estimate the heritability of responsiveness. a relatively high level of heritability (h2 = 0.49 +/- ... | 1994 | 7982749 |
| genetic variability of the beta-tubulin genes in benzimidazole-susceptible and -resistant strains of haemonchus contortus. | benzimidazole anthelmintics are the most common chemotherapeutic agents used to remove intestinal helminths from farm animals. the development of drug resistance within helminth populations is wide-spread and can render these drugs essentially useless. the mechanism of benzimidazole resistance appears to be common to many species ranging from fungi to nematodes and involves alterations in the genes encoding beta-tubulin. during the selection process resulting in resistance, there must be quantit ... | 1994 | 8001777 |
| characterization of a tandemly repetitive dna sequence from haemonchus contortus. | genomic dna from the sheep parasitic nematode haemonchus contortus was shotgun cloned in the plasmid vector puc18. recombinants which gave the strongest hybridization signals to 32p-radiolabelled genomic dna were selected as representatives of the repetitive component of the parasite dna. one repetitive sequence which hybridized only with dna from h. contortus and not with dna from two other sheep nematodes (trichostrongylus colubriformis and ostertagia circumcincta) was further characterized by ... | 1994 | 8021102 |
| anthelmintic resistance in australian sheep nematode populations. | the resistance status of gastro-intestinal nematodes to anthelmintics was evaluated on 881 sheep farms throughout australia during 1991-92. resistance was shown to be widespread. overall, 85% of farms had sheep infected with nematodes resistant to benzimidazole, 65% to levamisole and 34% to combination (benzimidazole+levamisole) products. resistance to ivermectin was not detected. on only 9% of farms did all anthelmintic groups reduce egg counts by greater than or equal to 95%. the culture of fa ... | 1994 | 8048907 |
| the effects of anthelmintics on ovine larval nematode parasite migration in vitro. | the anthelmintics ivermectin, levamisole, morantel tartrate and thiabendazole all inhibited, in vitro, the motility of third stage larvae (l3) of trichostrongylus colubriformis. the bioassay, based on the inhibition of l3 migration from agar gels, yielded sigmoid dose-response curves for ivermectin, levamisole and morantel tartrate, but not thiabendazole. the concentration of levamisole giving 50% inhibition of migration (ec50) was determined for cooperia curticei, haemonchus contortus, nematodi ... | 1994 | 8070948 |
| protection studies with integral membrane fractions of haemonchus contortus. | techniques for targetting glycoproteins integral to the luminal membrane of the intestinal cells of haemonchus contortus were used to isolate fractions of whole parasites with protective antigen potential. sheep immunization trials with various candidate fractions revealed one which selectively bound to lectins with specificity for n-acetylgalactosamine and which reduced mean challenge worm burdens by up to 72% and mean faecal egg counts by up to 93%. the luminal surface of the intestines of the ... | 1994 | 8072767 |
| rotational grazing for control of gastrointestinal nematodes of goats in a wet tropical environment. | a preliminary experiment involving contamination of pasture plots with eggs of haemonchus contortus, trichostronglyus colubriformis and oesophagostomum columbianum every month for a year established that in the tropical environment of the pacific island of tongatapu, hatching and development of all species was rapid and continuous, with a short survival on pasture (3-7 weeks) of the resulting infective larvae. these results indicated that a rotational grazing system consisting of ten paddocks gr ... | 1994 | 8091608 |
| anthelmintic resistance in haemonchus contortus from sheep in malaysia. | albendazole, oxfendazole, fenbendazole, levamisole, closantel, ivermectin and febantel were administered to sheep on four farms and their efficacy assessed by faecal egg count reduction test. high level of resistance of haemonchus contortus was found to benzimidazoles (albendazole, oxfendazole, fenbendazole) on all farms and to febantel on the one farm where it was tested. no resistance to closantel and levamisole was observed. resistance to ivermectin was absent on the three farms examined unde ... | 1994 | 8091619 |
| monoclonal antibody to cd4+ t cells abrogates genetic resistance to haemonchus contortus in sheep. | the roles of cd4+ and cd8+ t cells in genetically determined resistance of sheep to haemonchus contortus (a natural host-parasite relationship) was investigated by selectively depleting genetically resistant merino lambs of their cd4+ or cd8+ t cells by treatment with mouse monoclonal antibody (mab) specific for the appropriate determinant before and during challenge infection. administration of anti-cd4 mab to genetically resistant lambs completely abrogated their expression of genetic resistan ... | 1993 | 8094709 |
| effect of selection for benzimidazole resistance in haemonchus contortus on beta-tubulin isotype 1 and isotype 2 genes. | in vitro selection for benzimidazole (bz) resistance in the nematode haemonchus contortus, a parasite of sheep, suggested the involvement of beta-tubilin genes. two distinct beta-tubulin isotype classes were analyzed. selection with stepwise increased concentrations of bz showed for the first time that the increasing degrees of resistance correlate to a dual phase adaptation mechanism. at lower degrees of developing resistance, selection for a single beta-tubulin isotype 1 variant takes place. s ... | 1993 | 8096381 |
| catecholamines during development of the parasitic nematode, haemonchus contortus. | 1. catecholamines from infective larvae of haemonchus contortus were extracted, separated on hplc, and measured on an electrochemical detector. doma 18 ng/100,000 larvae: ne 6 ng: e 1 ng: da 1 ng 2. levels of norepinephrine decreased below detection level rapidly after gassing with co2. 3. levels of 3,4-dihydroxymandelic acid (doma), a metabolite of norepinephrine, increased when exsheathment took place in tap water rather than buffer. | 1993 | 8098687 |
| characterization and biological activities of anti-brugia pahangi tubulin monoclonal antibodies. | three monoclonal antibodies (mab) specific to beta-tubulin were used to investigate the heterogeneity of tubulins from nematodes and mammals. western blot analysis of one-dimensional sds-page showed that anti-brugia pahangi tubulin mab 1b6 and p3d react with epitope(s) specific to nematode beta-tubulin and recognize tubulin from adults and microfilariae of b. pahangi, adult b. malayi and dirofilaria immitis, eggs of haemonchus contortus and adult ascaris suum. however, the same mab did not recog ... | 1993 | 8106183 |
| the b cell dependence of haemonchus contortus antigen-induced lymphocyte proliferation. | the proliferative responses of ovine lymphocytes to soluble antigens of third-stage larvae of haemonchus contortus (hcag) were examined in vitro. lymphocytes in mononuclear cell cultures responded consistently to hcag even if the lambs were naive to h. contortus. lymphocytes from sheep that were immune to reinfection with h. contortus also consistently responded to hcag with a response significantly greater than that recorded from naive lambs. when the responses of t cell or b cell enriched frac ... | 1993 | 8106184 |
| detection of anthelmintic resistance by culture in vitro of parasitic stages of ovine nematodes. | exsheathed l3 larvae of haemonchus contortus were cultured at 38.5 degrees c in a complex medium supporting growth to adult worms. although there was a clear difference in response between susceptible and benzimidazole/ivermectin/closantel resistant h. contortus using thiabendazole, the test failed to differentiate satisfactorily between the strains using ivermectin or closantel. | 1993 | 8128582 |
| effects of time, from collection to processing, on the recovery of haemonchus contortus third-stage larvae from herbage. | being able to obtain accurate estimates for the number of haemonchus contortus third-stage larvae (l3) on pasture is essential to any type of strategy intended for control. the objective of this experiment was to study the effect of the time, from collection to processing, on the recovery rate of h. contortus l3 from herbage. separate herbage samples were inoculated with two treatments of a known amount of larvae on day 1 and then samples were processed from day 1 to day 30. this simulated infec ... | 1993 | 8128590 |
| detection of haemonchus contortus surface antigen in faeces from infected sheep. | an antigen capture enzyme-linked immunosorbent assay (elisa) has been developed that could identify haemonchus contortus antigens in dilute suspensions of worm homogenates and in faeces from sheep naturally infected with moderate burdens of the parasite. the elisa is based on a polyclonal (rabbit or sheep) antibody coated solid-phase that captures parasite antigen from a suspension of worms or faeces. the captured antigen is detected by a mouse monoclonal antibody (mab e2) that is reactive with ... | 1993 | 8128591 |
| [the behavior of hematological parameters (hemoglobin, hematocrit, leukocyte count) and clinicochemical values in plasma (glucose, total proteins, alpha-amino-n, urea, pepsinogen, ascorbic acid, fe, cu, zn) and the content of ascorbic acid in liver, spleen and adrenal glands in healthy lambs and lambs infected with haemonchus contortus and trichostrongylus colubriformis]. | in 8 healthy, noninfected lambs with an initial body weight (b. w.) of 24.79 +/- 1.16 kg as well as in 3 groups of lambs (n = 8 per group) of a similar body weight after an inoculation with 3rd stage larvae of haemonchus contortus (2500) and trichostrongylus colubriformis (10,000) analyses of the blood plasma were performed for 45 days thereafter. on the 37th day after infection ivermectin (0.2 mg/kg b. w.) was administered per os respectively subcutaneously to the lambs of 2 groups. after 7 and ... | 1993 | 8129699 |
| expression of cloned beta-tubulin genes of haemonchus contortus in escherichia coli: interaction of recombinant beta-tubulin with native tubulin and mebendazole. | two distinct beta-tubulin cdna isotypes (beta 8-9 and beta 12-16) from haemonchus contortus were expressed for the first time in escherichia coli and characterised by their specific mebendazole (mbz) binding and polymerization properties. beta-tubulin was expressed without translational fusion to an e. coli sequence under the regulation of the tryptophan promoter in the ptrp2 vector. beta-tubulin was produced in large amounts in insoluble 'inclusion bodies'. the inclusion bodies were purified an ... | 1993 | 8139621 |
| antibody-containing cells in the abomasal mucosa of sheep with genetic resistance to haemonchus contortus. | the frequency distribution of parasite-specific antibody-containing cells (acc) and total immunoglobulin-containing cells (icc) in the abomasal mucosa was examined in genetically resistant and random-bred sheep, following infection with haemonchus contortus, to determine whether the two genotypes differed in the development of a local immune response. immunofluorescence staining was used to detect acc and icc of iga, igg1, igg2 and igm classes. no acc were found in the abomasum of any of the she ... | 1994 | 8146452 |
| cloning and sequence analysis of the small subunit ribosomal rna gene from nematodirus battus. | the small subunit ribosomal rna gene (ssu rrna) from the nematode parasite, nematodirus battus, was cloned from amplified genomic dna using polymerase chain reaction primers complementary to the 5' and 3' ends of haemonchus contortus small subunit ribosomal dna (ssu rdna). the 1,758 base pair cloned fragment was sequenced in both directions using internally generated primers and aligned with those from the genus haemonchus. results indicated a 1.9% sequence difference between the genera with a 1 ... | 1994 | 8158485 |
| seasonal prevalence of gastrointestinal nematodes in communal land goats from the highveld of zimbabwe. | on six occasions during a 1 year period, goats run on communal pastures by small-scale farmers, were purchased, housed indoors for 3 weeks and autopsied for examination of their gastrointestinal nematode burden. all of the 32 goats examined were infected. the four dominant species, haemonchus contortus, trichostrongylus axei, trichostrongylus colubriformis and oesophagostomum columbianum, were present in 88-97% of the animals. three other nematodes, strongyloides papillosus, bunostomum spp. and ... | 1994 | 8171826 |
| development and recovery of haemonchus contortus first larval stages on experimental plots in mexico. | the objective of this study was to determine the influence of relative humidity, environmental temperature and precipitation on the development of haemonchus contortus from egg to infective larvae on experimental plots in a subtropical subhumid climate of mexico. the study was of 1 year duration, with the highest rates of recovery of first-stage (l1) and second-stage larvae (l2) obtained at the end of the rainy season, and of third-stage larvae (l3) in the post-rainy season during the autumn. th ... | 1994 | 8171829 |
| efficacy of moxidectin against gastrointestinal nematode infections in sheep. | the efficacy of moxidectin against gastrointestinal nematode infections was studied in 30 fleischschaf x rasa aragonesa male lambs aged 3 months at the beginning of the experiment. the lambs were distributed in three groups of 10 animals each and experimentally infected with a mixture of an equal number of infective (l3) larvae from each of the following species: haemonchus contortus (2000), ostertagia circumcincta (2000), trichostrongylus colubriformis (2000) and trichostrongylus vitrinus (2000 ... | 1994 | 8171833 |
| ivermectin binding sites in sensitive and resistant haemonchus contortus. | membranes from both ivermectin-sensitive and -resistant haemonchus contortus l3 larvae were examined for the presence of high affinity [3h]ivermectin binding sites. both tissue preparations displayed high affinity drug binding sites (kd = 0.13 nm). receptor density (bmax = 0.4 pmol/mg) was the same in both the sensitive and resistant nematodes suggesting that target site modification was not involved in the development of drug resistance in this particular strain of h. contortus. the h. contortu ... | 1994 | 8195956 |
| effect of subclinical eimeria species infections in tropical goats subsequently challenged with caprine haemonchus contortus. | fourteen goat kids of the local indigenous breed naturally infected with eimeria species were divided into two equal groups. the first group was superinfected with 500,000 eimeria species oocysts and the second group was treated with amprolium. sixty days later both groups were infected with 5000 third-stage caprine haemonchus contortus larvae. the goats experimentally superinfected with eimeria shed more h contortus eggs and gained weight more slowly. | 1994 | 8197681 |
| consequences of dose-dependent immunosuppression by progesterone on parasitic worm burdens in lambs. | eighteen female lambs with prior exposure to haemonchus contortus infections were ovariectomized and assigned to 1 of 3 replacement regimens: 0, 25, or 250 mg of progesterone/d delivered im. after 3 weeks of hormonal treatment, all lambs were inoculated with 100,000 infective larvae of h contortus. after 8 weeks of hormonal treatment, a blastogenic assay was performed on blood lymphocyte populations, and the abomasum from each lamb was obtained for larval and adult worm recoveries of h contortus ... | 1993 | 8214899 |
| irrigation, faecal water content and development rate of free-living stages of sheep trichostrongyles. | the effect of irrigation by flooding the pastures on the ability of the eggs of sheep trichostrongyles to develop into infective larvae (l3) was estimated in outdoor conditions by depositing parasitised faeces on plots, without irrigation or submerged, at different times and durations. the rates of development of teladorsagia circumcincta, trichostrongylus vitrinus and chabertia ovina were very low in spring and summer in dry plots but proportional to the duration of submersion in the irrigated ... | 1993 | 8220500 |
| haemonchus contortus: identification of proteases with diverse characteristics in adult worm excretory-secretory products. | host tissue penetration and feeding by helminth parasites may be mediated by both mechanical processes and histolytic products released by the parasites. to investigate potential histolytic products released by adult haemonchus contortus worms, proteases in excretory-secretory (es) products were analyzed. the optimum activity of es proteases was at ph 5.0, although activity was observed over a wide range of ph tested (ph 3.0-9.0). four protease bands were observed on gelatin-containing polyacryl ... | 1993 | 8224091 |
| an in vitro assay utilising parasitic larval haemonchus contortus to detect resistance to closantel and other anthelmintics. | a new assay for detecting resistance to anthelmintics in vitro is described. the assay uses a simple culture system in which the ability of anthelmintics to kill or inhibit the migration of parasitic third and fourth stage haemonchus contortus larvae through a 50 microns aperture mesh is assessed. the assay detects 2-10-fold resistance to closantel. resistance to benzimidazoles, levamisole and ivermectin can also be detected. | 1993 | 8225759 |
| comparative kinetic disposition of oxfendazole in sheep and goats before and during infection with haemonchus contortus and trichostrongylus colubriformis. | the kinetic disposition of [14c]-oxfendazole (ofz) and its metabolites, fenbendazole (fbz) and fenbendazole sulphone (fbz.so2), in plasma and abomasal fluid were determined in merino sheep and angora goats before and during infection with trichostrongylus colubriformis and haemonchus contortus. the systemic availability (area under the plasma curve, auc) of ofz was significantly lower in goats (13.5 micrograms.h/ml) than in sheep (22.2 micrograms.h/ml) and was reduced with infection in goats (5. ... | 1993 | 8230395 |
| activity of morantel citrate against strains of benzimidazole-resistant nematodes of sheep in the united kingdom. | the activity of morantel citrate (5.94 mg/kg base) was determined in laboratory tests against field isolates of benzimidazole-resistant nematodes. its efficacies against adult and seven-day-old worms were 100 per cent and 100 per cent for cooperia curticei, 95.1 per cent and 69.8 per cent for haemonchus contortus and 100 per cent and 82 per cent for ostertagia circumcincta. morantel citrate was 100 per cent effective against benzimidazole-susceptible nematodirus battus and trichostrongylus vitri ... | 1993 | 8236701 |
| 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 |
| ivermectin-resistant haemonchus contortus in australia. | | 1993 | 8240179 |
| lamb serum recognition of infective larvae and adult haemonchus contortus antigens. | sixteen- to eighteen-week-old lambs were infected with 2500 3rd stage larvae (l-3) of haemonchus contortus or kept as uninfected controls. two months later all animals were challenged with 5000 l-3 of this parasite. soluble antigens of h. contortus l-3 and adult worms were analyzed by sds-page and western blotting during experimental infection and challenge. antigens from both sources, particularly of low molecular weight under reducing conditions, were recognised by the pooled sera of infected ... | 1993 | 8249249 |
| laboratory selection for ivermectin resistance in haemonchus contortus. | a strain of haemonchus contortus, susceptible to ivermectin (ivm), was submitted to a selection procedure using ivm at 0.02 mg kg-1 during nine successive passages in lambs. treatment reduced worm egg counts (epg) by more than 99% up to the seventh passage, but thereafter there was no significant reduction in epg. the efficacy of ivermectin against the ninth selected generation compared with the original susceptible strain was assessed. the results showed that animals infected with the selected ... | 1993 | 8249250 |
| parasite spectrum and seasonal epidemiology of gastrointestinal nematodes of small ruminants in the gambia. | one hundred and four post mortem examinations of randomly selected sheep (52) and goats (52) were carried out weekly from march 1990 to february 1991. gastrointestinal parasites were identified and counted. a large spectrum of 16 helminth species was found in 101 (97%) infected animals. the nematodes infecting small ruminants were, in order of predominance: trichostrongylus colubriformis (96% of all animals), oesophagostomum columbianum (82%), haemonchus contortus (67%), strongyloides papillosus ... | 1993 | 8249251 |
| the prevalence of concurrent trypanosome and gastrointestinal nematode infections in west african dwarf sheep and goats in nsukka area of eastern nigeria. | the prevalence of concurrent nematode-trypanosome infections in traditionally reared west african dwarf sheep and goats in eastern nigeria was monitored over a 12-month period during 1987-1988. the most prevalent nematodes were haemonchus contortus and trichostrongylus colubriformis, which usually occurred together in all nematode infected animals. their combined prevalence rates ranged from 90 to 100% throughout the year and they accounted for 66 to 98% of the total monthly worm burdens. of the ... | 1993 | 8249254 |
| factors affecting the prevalence and severity of footrot in a merino flock selected for resistance to haemonchus contortus. | an outbreak of virulent footrot occurred in three lines of sheep selected for different levels of resistance to haemonchus contortus, providing an opportunity to examine the factors affecting footrot severity. the selection lines did not differ significantly in average footrot score, but various other factors were found to have an effect. in breeding ewes, the average score was 10.2 (maximum possible score 20) and the prevalence of footrot was 96%. there was a significant age effect, with averag ... | 1993 | 8257313 |
| benzimidazole resistance of haemonchus contortus in goats in malaysia. | | 1993 | 8279113 |
| acute or chronic administration of prolactin alters ovine infections of haemonchus contortus. | prolactin has been implicated as a modulator in the phenomenon of periparturient egg rise during ovine nematodiasis. in the first experiment, lambs (4 months of age) with patent infections (10,000 infective larvae) of haemonchus contortus were injected daily (days 28-39 post-inoculation (pi)) with prolactin (20 or 200 iu) or saline. fecal egg concentrations and total daily egg production were monitored for each lamb. after 12 days, lambs injected with the lower dose of prolactin had the highest ... | 1993 | 8291185 |
| the efficacy and persistent anthelmintic effect of ivermectin in sheep. | the direct efficacy and the long-term persistent anthelmintic effect of an oral suspension and an injectable formulation of ivermectin at a dose rate of 0.2 mg kg-1 was studied in sheep. lambs were infected experimentally with haemonchus contortus, trichostrongylus vitrinus and cooperia curticei. after 3 weeks they were treated with an oral suspension or with an injection, and reinfected with the same dose of larvae 3, 6 or 10 days after treatment. post-mortem worm counts showed no persistent ef ... | 1993 | 8291186 |
| comparison of the effects on milk production of concurrent infection with haemonchus contortus and trichostrongylus colubriformis in high- and low-producing dairy goats. | the impact of nematode parasitism of the digestive tract on milk output and milk quality was examined in dairy goats. in addition, the consequences of worm infection were compared in goats with different lactation performance (ie, with initial high or low milk production). forty-eight goats in the second month of lactation were allotted equally to 2 groups. the first group was given 5,000 haemonchus contortus and 20,000 trichostrongylus colubriformis larvae. the 24 additional goats remained free ... | 1993 | 8291768 |
| acetylcholinesterase in infective-stage larvae of haemonchus contortus, ostertagia circumcincta and trichostrongylus colubriformis resistant and susceptible to benzimidazole anthelmintics. | the amounts of acetylcholinesterase (ache) in homogenates of infective-stage larvae of strains, from different countries, of haemonchus contortus, ostertagia circumcincta and trichostrongylus colubriformis resistant or susceptible to benzimidazole (bz) anthelmintics, were compared using a rapid colorimetric assay. the levels of ache were much greater in those strains which were bz-resistant than in bz-susceptible populations. the larvae of susceptible and resistant h. contortus contained less ac ... | 1993 | 8295794 |
| cloning and characterization of ribosomal rna genes from three species of haemonchus (nematoda: trichostrongyloidea) and identification of pcr primers for rapid differentiation. | genomic dnas prepared from adult worms of haemonchus contortus, haemonchus placei, and haemonchus similis were used to clone and map complete ribosomal rna gene repeats from each species. the lengths of the repeating units were estimated at 7.2, 7.2, and 7.4 kb, respectively, with a second and distinct repeat 6.9 kb in length identified from h. contortus only. restriction enzyme recognition sites within all ribosomal rna genes were fully conserved except for the loss of a sali site within the la ... | 1994 | 8299758 |
| susceptibility of two crossbreeds of sheep to haemonchus contortus. | studies were conducted on 20 crossbred lambs of 4-5 months old. ten lambs were nali x corriedale cross (hisardale) and the other 10 were nali x lohi cross (munjal). seven lambs each of both crossbreeds were infected with 10,000 infective larvae of haemonchus contortus. three lambs of each crossbreed served as uninfected controls. clinicopathological examinations were done before and after infection and all the lambs were necropsied 28 days post-infection. the body weight gain, haemoglobin and pa ... | 1993 | 8300294 |
| persistence of acquired immunity to trichostrongylus colubriformis in sheep after termination of infection. | lambs were infected with 6000 trichostrongylus colubriformis l3 per week for 18, 12 or 6 weeks, beginning at ages 14, 20 and 26 weeks, respectively. at the end of the primary infection subgroups had geometric mean adult worm burdens of 5000, 15,000 and 18,000, respectively. in the remaining sheep the worm population was removed with anthelmintic, and sheep had no further larval intake until challenged with t. colubriformis 1, 6, 12, 18 or 24 weeks later. in the groups given 18 or 12 weeks primar ... | 1993 | 8300297 |
| new morphological characters for identifying individual specimens of haemonchus spp. (nematoda: trichostrongyloidea) and a key to species in ruminants of north america. | the large stomach worms haemonchus contortus, haemonchus placei, and haemonchus similis are important pathogens of cattle and sheep. this paper describes characteristics of surface cuticular ridges (synlophe), which for the first time provide morphological criteria for identifying individual adult specimens of either sex. the diagnostic patterns of the synlophe on the anterior half of specimens can be observed at 400x in temporary mounts on glass slides. the synlophe can be studied in cleared pr ... | 1994 | 8308643 |
| rejection of heterologous nematodes by sheep immunized with larval or adult trichostrongylus colubriformis. | sheep immunized by truncated larval infections or by the adoptive transfer of adult trichostrongylus colubriformis were subsequently challenged with single infections of t. colubriformis, nematodirus spathiger, haemonchus contortus or ostertagia circumcincta or combinations of the parasites. sheep vaccinated with larval infections were > 90% protected by 4 days after challenge (dac) against t. colubriformis l3 given in a single or combined infection, whereas no significant protection was exhibit ... | 1993 | 8314366 |
| kinetics of expulsion of haemonchus contortus from sheep and jirds after treatment with closantel. | experiments were conducted in sheep after intramuscular treatment with closantel and in jirds after oral treatment with closantel to determine when expulsion of established h. contortus commences. expulsion starts at about 8 h in sheep and coincides with the onset of reduced motility in worms recovered from the abomasum. in jirds, expulsion starts by 2 h after treatment. experiments also conducted in jirds showed that infective larvae are first killed by circulating closantel 3 days after infect ... | 1993 | 8314373 |
| characterization of proteinases in extracts of adult haemonchus contortus, the ovine abomasal nematode. | the degradation of several protein substrates, including the blood proteins haemoglobin, albumin and fibrinogen, by proteinases present in extracts of adult haemonchus contortus was examined over a broad ph range. these proteinases were further characterized on the basis of substrate specificity, inhibitor sensitivity and molecular size by spectrophotometric and substrate gel analysis. the majority of the proteinases capable of degrading the blood proteins tested were active at acidic ph and cou ... | 1993 | 8316437 |
| model predictions for anthelmintic resistance amongst haemonchus contortus populations in southern brazil. | a computer model developed to study ostertagia circumcincta resistance to anthelmintics in uk sheep flocks has been adapted for use with haemonchus contortus under southern brazilian conditions. the model simulates the effect of different anthelmintic control regimens on the year-to-year pattern of resistance in breeding ewes. the nematode control regimen most used by brazilian sheep farmers was found to increase the frequency of genes which confer resistance from approximately 3% to 14% in an h ... | 1993 | 8333136 |
| the ecology of animal parasitic nematodes in endemic areas of jos, nigeria. | a survey involving 3418 faecal samples collected from three areas of heavy human and animal activities in jos, nigeria showed that 2354 (68.9%) of the samples harboured various parasitic nematodes of man and animals. altogether, twelve species of parasitic nematodes were encountered. five of these, namely: ascaris lumbricoides, ancylostoma duodenale, necator americanus, trichuris trichiura and strongyloides stercoralis infect man while five others: trichostrongylus probolurus, t. colubriformis, ... | 1993 | 8334456 |
| immune responsiveness of lambs selected for resistance to haemonchosis. | several parameters of immune competence were measured in lambs with genetic resistance to haemonchus contortus and in lambs with average susceptibility to h contortus (random-bred). increase in skinfold thickness following intradermal injection was greater in resistant lambs for concanavalin a and to a lesser extent for phytohaemagglutinin. both mitogens induced infiltration of superficial and deep dermis by eosinophils, cd4+, cd8+ and t19+ lymphocytes, though the responses did not differ betwee ... | 1993 | 8337484 |
| haemonchus contortus: ivermectin-induced paralysis of the pharynx. | how the avermectins cause the elimination of gastrointestinal nematodes from host animals has not yet been clearly identified. using visual and radiometric parameters to measure oral ingestion in haemonchus contortus, we showed that ivermectin (ivm) rapidly inhibited ingestion at concentrations > or = 10(-10) m. motility, monitored quantitatively with an automated motility meter, was unaffected by ivm at concentrations < or = 10(-8) m, while atp levels were unaffected at concentrations < or = 10 ... | 1993 | 8344410 |
| haemonchus contortus: a challenging parasite from immunological point of view. | | 1993 | 8346663 |
| the effect of feed intake on the rate of flow of digesta and the disposition and activity of oxfendazole in sheep. | within 3 h of intra-ruminal (ir) administration oxfendazole (ofz) was extensively associated with digesta particulate material. this association appeared to be a passive adsorption/desorption since sheep given dose equivalent ofz which was contained solely in rumen particulate digesta (obtained from ofz treated donor sheep) exhibited similar ofz disposition to the ir treated animals. the association of ofz with rumen particulate digesta is a major determinant of the pharmacokinetic behaviour of ... | 1993 | 8354599 |
| longistrongylus curvispiculum (nematoda: trichostrongyloidea) in free-ranging exotic antelope in texas. | longistrongylus curvispiculum was recovered from free ranging sable (hippotragus niger), addax (addax nasomaculatus) and biesa oryx (oryx beisa) on two ranches in central texas (usa). these nematodes represented a small portion of the total abomasal worm burden dominated by haemonchus contortus. female l. curvispiculum easily could be confused with other ostertaginae, but the spicules of the males were diagnostic. | 1993 | 8355363 |
| in vitro activity of paraherquamide against the free-living stages of haemonchus contortus, trichostrongylus colubriformis and ostertagia circumcincta. | paraherquamide, an oxindole alkaloid recently reported to have potent nematocidal activity, was shown to have a marked inhibitory effect on the motility of the free-living larval stages of h. contortus, t. colubriformis and o. circumcincta. the effect of paraherquamide on larval motility could be distinguished from that caused by levamisole and the avermectins. after 72 h exposure, the concentration of paraherquamide required to inhibit the motility of 50% of l3 larvae present was 0.033, 0.058 a ... | 1993 | 8359986 |
| an outbreak of haemonchosis associated with anthelmintic resistance in sheep. | an outbreak of haemonchosis associated with anthelmintic resistance was recorded in a flock of 150 crossbred lambs. closantel and ivermectin were 100% effective against haemonchus contortus while fenbendazole and morantel reduced faecal egg counts by 87 and 29%, respectively. levamisole showed an efficacy of 95%. at double the recommended dose (10 mg kg-1), fenbendazole had an efficacy of 99% against h. contortus infection. this appears to be the first report of an outbreak of haemonchosis assoc ... | 1993 | 8359992 |
| species-specific pcr for the parasitic nematodes haemonchus contortus and trichostrongylus colubriformis. | reliable species determination of gastrointestinal nematode parasites from sheep is usually carried out on third-stage larvae (l3) by visual differentiation. the culturing of l3 takes about 1 week so a reliable method that could use eggs for the determination would accelerate the procedure. we developed a polymerase chain reaction (pcr), using very small amounts of parasite dna and an oligonucleotide set according to parts of the dna sequence of a beta-tubulin gene from haemonchus contortus, tha ... | 1993 | 8359994 |
| demonstration of co-resistance of haemonchus contortus to ivermectin and moxidectin. | studies were conducted to determine whether organisms which are resistant to ivermectin are also resistant to moxidectin. the mechanisms of action of moxidectin and ivermectin were compared by measuring the changes in membrane conductance they induced in leg muscle fibres of the common shore crab (pachygrapsus crassipes) by using standard micro-electrode techniques. meriones unguiculatus (jirds) were infected with ivermectin-resistant or -susceptible strains of haemonchus contortus, treated with ... | 1993 | 8362470 |
| molecular characterisation of beta-tubulin genes present in benzimidazole-resistant populations of haemonchus contortus. | a beta-tubulin isotype 1 gene, gru-1, from a benzimidazole (bz)-resistant population of the nematode parasite, haemonchus contortus, was cloned and sequenced. the predicted gene organisation showed 10 exons and 9 introns, one of which was h. contortus specific. using probes and restriction sites selected from this sequence, restriction maps were constructed from and around beta-tubulin genes of 3 bz-susceptible and 7 bz-resistant populations. there was a reduction in beta-tubulin isotype 1 genes ... | 1993 | 8366887 |
| systemic responses to challenge infection with haemonchus contortus in immune merino sheep. | some systemic responses to single-dose infection with 10,000 haemonchus contortus infective larvae were examined in sheep already shown to have protective immunity against the parasite. the major haematological finding was a neutrophil leukocytosis that occurred after the infections became patent but not during the pre-patent period. there was no definitive eosinophilia and no discernible change in the erythrocyte parameters. systemic hyperthermia was not conclusively evident during the pre-pate ... | 1993 | 8367936 |
| ascaris suum: cloning of a cdna encoding phosphoenolpyruvate carboxykinase. | a cdna encoding phosphoenolpyruvate carboxykinase (pepck) from ascaris suum was cloned by complementation of a strain of escherichia coli deficient in pepck and malic enzyme. the product of this cdna was enzymatically similar to a recombinant pepck obtained from haemonchus contortus by the same method. comparison of the predicted amino acid sequence of a. suum pepck with other pepcks showed that this enzyme is most closely related to the h. contortus enzyme. the two nematode enzymes share consid ... | 1993 | 8375484 |
| evaluation of aspects of the protection afforded to sheep immunised with a gut membrane protein of haemonchus contortus. | experiments were undertaken to evaluate the type of protection conferred against haemonchus contortus by immunising sheep with h11, a 'hidden' integral gut membrane protein isolated from this parasite. a serial kill experiment showed that worms began to be lost from immunised lambs between seven and 14 days after challenge with a single dose of larvae and adult female worms were more susceptible than male worms. seven-day-old juveniles survived immunisation even though their intestinal cells bec ... | 1993 | 8378601 |
| protection in lambs immunised with haemonchus contortus gut membrane proteins. | substantial protection against haemonchus contortus was induced in lambs by hyperimmunising them with an integral membrane extract of intestines dissected from adult worms. the procedure was effective in young growing animals but did not afford any cross protection against either ostertagia circumcincta or nematodirus battus. a serum transfer experiment suggested that the effector mechanism was serum antibody which bound to the brush border membrane of the parasites intestinal cells. sheep which ... | 1993 | 8434155 |
| efficacy of abamectin against nematodes in cattle. | eight controlled trials were conducted, using 96 cattle of european breeds, to evaluate the efficacy of abamectin against natural and artificially acquired infections of adult and fourth-stage larvae of all the economically important gastrointestinal nematodes and lungworms in germany and the united kingdom. half the animals were treated on one occasion with abamectin at a dose of 200 micrograms/kg bodyweight given subcutaneously while the other half remained untreated. worms were counted 14 or ... | 1993 | 8442334 |
| isotype-specific antibody responses to haemonchus contortus in genetically resistant sheep. | the kinetics of anti-haemonchus antibody responses in serum and faecal extracts of pasture-reared, genetically resistant and random-bred sheep infected with haemonchus contortus were examined using an isotype-specific elisa. anti-haemonchus antibodies of iga, igg1, igg2 and igm isotypes were detected in serum and faecal extracts of both resistant and random-bred sheep after challenge infection. serum igg1 and iga levels in resistant sheep were significantly higher than in random-bred sheep betwe ... | 1993 | 8446465 |
| effect of subclinical coccidiosis in kids on subsequent trichostrongylid infection after weaning. | seven-week-old female kids of the murciana-granadina breed naturally infected with coccidia were superinfected with a multispecific eimeria inoculum (300,000 oocysts) or treated to control the coccidial infection with amprolium (50 mg kg-1 liveweight day-1; 4 days every 14 days); 80 days later both animal groups received 2500 third-stage larvae of a sheep-derived mixture of trichostrongylus colubriformis (50%), teladorsagia circumcincta (40%) and haemonchus contortus (10%). kids experimentally s ... | 1993 | 8447060 |
| the ecology of haemonchus contortus in a winter rainfall region in australia: the development of eggs to infective larvae. | the seasonal pattern of development of haemonchus contortus eggs to infective larvae was investigated on the south coast of western australia. sheep faeces containing h. contortus eggs were deposited on pasture plots at intervals over a 3-year period, and pasture grass and faeces were sampled periodically for infective larvae (l3). the maximum recoveries occurred in late autumn and in late spring, when adequate moisture coincided with warm temperatures. larval development was low and sporadic ov ... | 1993 | 8447070 |
| the ecology of haemonchus contortus in a winter rainfall climate in australia: the survival of infective larvae on pasture. | at sites near albany, on the south coast of western australia, sheep faecal pellets containing either eggs or infective larvae (l3) of haemonchus contortus were deposited onto natural pasture plots at intervals over 3 years. faecal and pasture samples were collected periodically and processed to detect l3. on annual pasture plots, l3 were recovered for from 10 to over 20 weeks from depositions made between autumn and early spring, at which time temperatures were mild or low, rainfall was frequen ... | 1993 | 8447071 |
| survival and development of ivermectin-resistant or susceptible strains of haemonchus contortus under field and laboratory conditions. | the free-living development of three strains of haemonchus contortus was studied in two experiments. day 21 faecal samples were collected from lambs infected with either a susceptible strain, a laboratory-selected ivermectin (ivm) resistant strain or a south african field strain showing multiple anthelmintic resistance, which included ivm. no eggs hatched in samples cultured at 4 or 10 degrees c. at 22 degrees c the laboratory-selected strain showed the highest rate of development while at 27 de ... | 1993 | 8460253 |
| the same fractions of haemonchus contortus soluble antigen induce lymphocyte responses in naive lambs and immune sheep. | soluble antigen extracted from third stage larvae of haemonchus contortus was divided into fractions based on molecular weight by sodium dodecyl sulphate polyacrylamide gel electrophoresis and electrotransferred to nitrocellulose. infection immunised adult sheep and h contortus naive lambs were used to examine the lymphocyte responses to these fractions in vitro. the results demonstrate that the same two fractions induced the strongest responses in both groups of animals. | 1993 | 8460267 |
| efficacy of closantel against fenbendazole and levamisole resistant haemonchus contortus in small ruminants. | sheep infected with a fenbendazole resistant strain of haemonchus contortus and goats with a levamisole resistant strain of the same parasite were used to evaluate the anthelmintic efficacy of closantel. closantel at the rate of 10 mg/kg body weight was 100% effective against the 2 resistant strains of the parasite as indicated by faecal egg count and worm reduction. the efficacy of fenbendazole in sheep and of levamisole in goats was 56.68 and 76.90%, respectively. | 1993 | 8465440 |
| ecdysteroids during development in the ovine parasitic nematode, haemonchus contortus. | 1. samples of embryonating eggs, infective larvae, fourth-stage larvae, young adults, and male and female mature adults of haemonchus contortus were collected for steroids analysis; lipids were extracted, partially purified, fractionated with hplc, and analyzed for ecdysteroids by radioimmunoassay. 2. free ecdysone and 20-hydroxyecdysone were detected in all samples; maximal concentrations occurred in the fourth-stage larvae and young adults. 3. conjugated ecdysone and 20-hydroxyecdysone were de ... | 1993 | 8472534 |
| vaccination of merino lambs against haemonchosis with membrane-associated proteins from the adult parasite. | groups of south african, farm-reared merino lambs about 4 months old were vaccinated with extracts of adult haemonchus contortus enriched with h11, an integral membrane protein from the parasite's intestinal microvilli, or with proteins soluble in tween 20. the lambs were challenged with 5000 infective 3rd-stage larvae. compared to the adjuvant-injected controls, lambs vaccinated with 350 micrograms/kg liveweight of the h11-enriched extract showed an 89% reduction in parasite egg production and ... | 1993 | 8479802 |
| biochemistry of the nematode cuticle: relevance to parasitic nematodes of livestock. | the cuticle of nematodes is a thin, flexible outer covering composed primarily of protein with trace amounts of lipid and carbohydrate. there has been considerable recent interest in the biochemistry, immunology and molecular biology of the cuticle of parasitic nematodes because of its role as an interface between parasite and host. the cuticle consists of: (1) collagen-like proteins that form the medial and basal layers; (2) non-collagen proteins that form the epicuticular and external cortical ... | 1993 | 8484203 |
| the role of inhibited development in the epidemiology of ostertagia infections. | seasonal patterns of inhibited larval development have been described for ostertagia spp. from many parts of the world; winter inhibition is found in areas where transmission of infections occurs mainly in summer and summer inhibition in areas where transmission is mainly from autumn to spring. there is no fixed regional seasonal inhibition pattern. depending on weather and farm management, the timing and level of inhibition will vary from year to year. moreover, differences in the propensity fo ... | 1993 | 8484216 |
| a key to the identification of arrested gastrointestinal nematode larvae of sheep in britain. | a simple key is presented for the identification of arrested larval nematodes recovered from the gastrointestinal tract of sheep slaughtered in britain. the parasites included in this key are those species which are most commonly seen to undergo arrested development in sheep. they include teladorsagia (ostertagia) spp., haemonchus contortus, trichostrongylus axei, intestinal trichostrongylus spp., nematodirus battus, nematodirus filicollis, and cooperia spp. easily identifiable morphological fea ... | 1993 | 8493769 |
| the potential value of integral membrane proteins in the vaccination of lambs against haemonchus contortus. | an extract of adult haemonchus contortus enriched in the parasite's intestinal microvillar membrane protein h11 and other integral membrane proteins but free of the protein contortin was evaluated as a potential vaccine in two breeds of sheep. the worm burdens of clun forest sheep injected with the extract and challenged with 25,000 infective larvae were reduced 89% by weight compared to the average for the controls. the worm burdens of dorset sheep (challenged with 10,000 infective larvae) were ... | 1993 | 8496009 |
| purification and evaluation of the integral membrane protein h11 as a protective antigen against haemonchus contortus. | a detergent extract of adult haemonchus contortus enriched in the integral membrane protein h11, previously shown to give protective immunity against the parasite, was fractionated by lectin and ion-exchange chromatography. the fractions were evaluated for their ability to immunize clun forest and dorset horn sheep against experimental haemonchosis. most of the protective activity was associated with h11. used in an approximately 95% pure form it gave a mean reduction in parasite egg output of 9 ... | 1993 | 8496010 |
| efficacy of moxidectin against internal parasites of sheep. | the efficacy of injectable and oral formulations of moxidectin, at a dosage of 0.2 mg kg -1 live mass was evaluated by the non-parametric method (npm) against the most common internal parasites of sheep in 9 trials involving a total of 201 sheep. both formulations obtained an a classification (more than 80% effective in more than 80% of the treated animals) against the third (l3) and fourth (l4) larval and adult stages of haemonchus contortus, teladorsagia circumcineta, trichostrongylus colubrif ... | 1993 | 8496891 |
| the pattern of faecal egg output in lambs infected with a multiple resistant strain of haemonchus contortus after treatment with albendazole. | worm-free lambs (n = 6) were infected with 5,000 l3 of an ivermectin/benzimidazole/closantel resistant strain of haemonchus contortus. on day 21 post infection animals were allocated, according to worm egg counts, to 2 groups of 3 animals each and on day 29 one group was treated with albendazole at 3.8 mg kg-1, while animals in the other group remained untreated as controls. all animals were slaughtered on day 44 when the treated group was found to have 2,083 +/- 1,718 worms and the controls 2,7 ... | 1993 | 8496892 |
| efficacy of moxidectin against a strain of haemonchus contortus resistant to ivermectin, a benzimidazole and a salicylanilide. | the efficacy of moxidectin at 0.2 mg kg-1 live body mass against the multiple anthelmintic resistant white river krtz strain of h. contortus was determined and compared to that of ivermectin, a benzimidazole, a salicylanilide and levamisole. moxidectin and levamisole were effective against this strain of h. contortus and reduced the arithmetic mean burdens of this parasite in the sheep by 99.98% and 99.59%, respectively, while the efficacy of ivermectin, albendazole and closantel was only 29.1%, ... | 1993 | 8496899 |
| controlled tests of activity of several antiparasitic compounds against natural infections of haemonchus contortus and other helminths in lambs from a flock established in 1962. | antiparasitic activity of several compounds was evaluated over a long period (about 25 years) in the same flock of sheep. haemonchus contortus was of special interest, including its relation to drug resistance, especially to thiabendazole and other benzimidazoles, in addition to phenothiazine. eleven compounds were evaluated in 15 controlled tests, done between 1966 and 1989 in naturally infected lambs (n = 145) born and raised on the same pasture. sheep were first placed on the pasture in 1962, ... | 1993 | 8498743 |