| the effects of photoperiod during development and of storage on maturation of haemonchus contortus larvae. | | 1977 | 915637 |
| anthelmintic activity of albendazole against gastrointestinal nematodes in calves. | anthelmintic activities of albendazole were evaluated in a controlled experiment. forty calves experimentally infected with gastrointestinal nematodes were allotted to 4 groups. calves in group 1 were used as nonmedicated controls; calves in groups 2, 3, and 4 were given (by oral route) a suspension containing albendazole at dose concentrations of 2.5, 5.0, and 7.5 mg/kg of body weight on the 35th day after administration of infective nematode larvae. in groups 2, 3, and 4 calves, average overal ... | 1977 | 921039 |
| effect of temperature on survival of free-living stages of haemonchus contortus. | one percent or more unembryonated eggs of haemonchus contortus survived in sheep fecal pellets less than 0.5 hour at -95 c, 2 hours at -28 c, 1 hour at -10 c, 4 days at 4 c, and 1 hour at 45 c. one percent or more embryonated eggs survived 1 hour at -95 and -28c, 12 hours at -10 c, 64 days at 4 c, and 12 hours at 45 c. over half the unembryonated and embryonated eggs survived only 1 and 4 days, respectively, at 4 c. one percent or more 1st-stage larvae did not survive 0.5 hour at -95 c but did s ... | 1976 | 949128 |
| the anthelmintic efficacy of fenbendazole against thiabendazole-resistant strains of haemonchus contortus and trichostrongylus colubriformis in sheep. | the anthelmintic efficacy of fenbendazole (methyl 5-(phenylthio)-2-benzimidazole carbamate) was tested in sheep against standardised strains of hcaemonchus contortus and trichostrongylus colubriformis, known to be resistant to thiabendazole (ld90 for thiabendazole against h ontortus was 200 mg/kg bodyweight and against t colubriformis was 150 mg/kg). fenbendazole at dose rates of 5, 10 and 20 mg/kg per os reduced total worm counts in h contortus infected sheep by 66, 90 and 100 per cent respecti ... | 1976 | 968192 |
| response of haemonchus contortus cayugensis to a change in the ratio of smooth to linguiform. | the equilibrium of vulvar phenotypes in haemonchus contortus cayugensis was changed by infecting lambs with either a selected strain of smooth or of linguiform worms. subsequently the lambs grazed the same pasture and observations were made on changes in worm populations in the lambs, and on pasture it appeared that the seasonal change in the relative frequencies of a and b linguiform worms was related to density-dependent factors in the host. in the spring, when lambs first become infected, the ... | 1976 | 980542 |
| biological controls in mixed trichostrongyle infections. | the parasite reaction phenotype of 80 lambs was determined with natural infection on pasture. these lambs were then assigned to outcome groups and randomized into treatment groups. developing some simple but unusual analytical techniques it was possible to demonstrate that mixed natural infections of trichostrongyles with the chief biomass component haemonchus contortus cayugensis protected against superinfections with 35000 infective larvae but protected against superinfections with 1000 infect ... | 1976 | 985666 |
| changes in the hatch rate of haemonchus contortus eggs between geographic regions. | vulvar phenotypes and the rate of development of eggs over a range of temperatures were used to compare haemonchus contortus populations in new york state and ohio. these parameters indicated that the westernmost boundary of the subspecies haemonchus contortus cayugensis is the chautauqua valley in new york. the haemonchus ecotype in ohio had a vulvar phenotype formula similar to that described for the subspecies haemonchus contortus contortus. the relationship between slope and intercept of the ... | 1976 | 988532 |
| the ageing process in infective larvae of the roundworms haemonchus contortus and nippostrongylus brasiliensis: carbohydrate content. | trehalose, glycogen and traces of glucose were the only anthrone sensitive carbohydrates identifiable. the variation of 13-22% of the dry weight in different populations of haemonchus contortus l3 is shown to be due to their capacity to synthesize glycogen during ageing. this contrasts with the larvae of nippostrongylus brasiliensis in which a low level of carbohydrate remains constant with time. it is suggested that h. contortus can convert lipid to carbohydrate as is the case for several other ... | 1976 | 988680 |
| experimentally induced haemonchus contortus infections in the rabbit. | haemonchus contortus originally derived from an ontario field strain was used to infect laboratory rabbits. both enshealthed and artificially exsheathed larvae were given at doses of up to 10 million larvae per rabbit. only artifically exsheathed larvae were infective and a dose of at least 50,000 was required to produce a significant level of infection. h. contortus completed its development in the rabbit, but at a slower rate than in the sheep. although a few fecund females were found 35 days ... | 1976 | 993571 |
| efficacy of albendazole against gastrointestinal nematodes of cattle. | forty-five calves with artificial and pasture-acquired nematode infections were medicated with albendazole at dose levels of 0, 2.5, 5.0, or 10 mg/kg of body weight. a dose level of 2.5 mg/kg removed at least 99% of adult trichostrongylus axei, trichostrongylus colubriformis, cooperia oncophora, and bunostomum phlebotomum. burdens of haemonchus contortus, strongyloides papillosus, and ostertagia ostertagi were reduced 79, 88, and 97%, respectively. at a dose level of 5.0 mg/kg, at least 95% of a ... | 1976 | 999077 |
| nematodes parasitizing domestic ruminants in afghanistan. | a total of 12 nematode species were determined in the collection recovered from domestic ruminants in afghanistan. ten of them were found for the first time in this region: trichocephalus globulosus, trichostrongylus probolurus, cooperia bisonis, nematodirus spathiger, n. abnormalis, thelazia rhodesi, bunostomum phlebotomum, haemonchus contortus, dictyocaulus filaria and oesophagostomum radiatum. morphological and metrical characteristics of t. globulosus, t. skrjabini and c. bisonis, based on o ... | 1976 | 1034588 |
| pathophysiology of single and challenge infections of haemonchus contortus in merino sheep: studies on red cell kinetics and the "self-cure" phenomenon. | | 1975 | 1078813 |
| manifestations of resistance to haemonchus contortus in sheep: worm populations and abomasal changes in sheep superinfected with 1,000,000 larvae of h. contortus. | | 1975 | 1116899 |
| haemonchus contortus: new data on its genetic constitution. | | 1975 | 1126417 |
| failure to vaccinate lambs against haemonchus contortus with functional metabolic antigens identified by immunoelectrophoresis. | | 1975 | 1140881 |
| the anthelmintic efficacy of fenbendazole against a mixed nematode infection in sheep. | fenbendazole (methyl-5-(phenylthio)-2-benzimidazole carbamate) at dose rates of 5 mg/kg and above was 100 per cent effective in eliminating a naturally acquired dictyocaulus filaria infection in sheep. the drug was 100 per cent effective in eliminating concurrent infections of adult trichostrongylus axei, haemonchus contortus, haemonchus placei, ostertagia circumcincta, ostertagia ostertagii, cooperia oncophora, cooperia mcmasterii, nematodirus spathiger, neumatodirus filcollis, oesophagostomum ... | 1975 | 1153893 |
| the effect of ageing on the antigenicity of haemonchus contortus larvae. | viable haemonchus contortus larvae used as a source of antigen in complement fixation tests showed a decrease in antigenic potency following storage for approximately two months at 5 degrees c. in contrast, larvae killed by freezing and stored at --15 degree c showed no such decline over a similar period. it is suggested that this loss of potency with ageing may be partly responsible for increased worm populations in sheep in spring. | 1975 | 1153895 |
| age group interaction of haemonchus contortus in premunized lambs. | lambs premunized with a relatively less pathogenic (rlp) isolate of haemonchus contortus were challenge exposed each day with 500 3rd-stage larvae (l3) of a normally pathogenic isolate of the same worm, starting on day 9 of the premunition-induced infection. in 6-month-old lambs, there was a fourfold decrease in egg production by the premunizing rlp isolate with challenge exposure compared with egg production in lambs given only the premunizing rlp isolate and not challenge exposed. premunized l ... | 1975 | 1155835 |
| effect of cambendazole, thiabendazole, and levamisole on fumarate reductase in cambendazole-resistant and -sensitive strains of haemonchus contortus. | | 1975 | 1165565 |
| cross-resistance to other anthelmintics in an experimentally produced cambendazole-resistant strain of haemonchus contortus in lambs. | | 1975 | 1165566 |
| the use of disophenol in studies of the pathogenicity of the arrested fourth-stage larvae of haemonchus contortus in the sheep. | disphenol was administered to sheep infected with haemonchus contortus in order to prevent the development of populations of adult worms, and studies were made of the pathogenicity of the arrested fourth-stage larvae which remained. the treated sheep showed elevated plasma pepsinogen and abomasal ph, predominantly negative dry-matter balance, and evidence of greater fluid loss, including plasma, into the gastro-intestinal tract. it was concluded that arrested larvae may cause damage to the aboma ... | 1975 | 1166136 |
| inhibited development in haemonchus contortus. | inhibited development of haemonchus contortus was studied in single experimental infections of worm-free lambs. chilling of the infective larvae at +4 degrees c was without effect on the percentage of larvae subsequently becoming inhibited and a period of exposure to autumnal conditions was unnecessary to induce a high rate of inhibition. it was concluded that seasonal inhibition of h. contortus in east anglia is brought about primarily by an environmental stimulus acting upon the preparasitic s ... | 1975 | 1187184 |
| field studies on inhibition of haemonchus contortus. | the epidemiology of haemonchus contortus was studied in north east england in lambs reared under field conditions with infected ewes. the parasite population was monitored by pasture larval counts, faecal egg counts and lamb postmortems. from 25 june to 11 november, eight lambs were slaughtered each month, together with eight worm-free tracer lambs. postmortem worm counts showed that on 25 june, small numbers of adult h. contortus were present but no inhibited larvae. however, subsequently the n ... | 1975 | 1187186 |
| observations on the development of haemonchus contortus in young sheep given a single infection. | worm free lambs 2-4 months old were given a single infection of 50,000 haemonchus contortus larvae. the changes in packed red cell volume were compared with those of uninfected sheep and the infected sheep were divided into two groups according to the rate of change of packed cell volume. in group 1, packed cell volume fell sharply from the 10th day of infection and the sheep eventually died. in group 2, the fall was less marked and the packed cell volume returned to normal after about 40 days. ... | 1975 | 1202415 |
| the resistance of a field strain of haemonchus contortus to five benzimidazole anthelmintics in current use. | using artificially infected sheep, the response of a laboratory strain of haemonchus contortus, which had not been subjected to anthelmintics for three years, was compared with that exhibited by a parbendazole resistant field strain following treatment with each of seven anthelmintics, the laboratory strain proved fully susceptable to thiabendazole, parbendazole, cambendazole, mebendazole, fenbandazole, levamisole and haloxon, in contrast to the field strain which showed a moderate to marked res ... | 1975 | 1223291 |
| micrometeorological factors involved in development and survival of free-living stages of the sheep nematodes haemonchus contortus and trichostrongylus colubriformis. a review. | | 1975 | 1232063 |
| relationship of pasture rotation to acquisition of gastrointestinal nematodes by sheep. | in a study of the relationship between pasture rotation in illinois and acquisition of nematodes (mostly haemonchus contortus) and body weight gains by lambs grazing with their ewes, 2 pasture rotation systems were tested. (1) lambs and ewes were rotated through a series of 12 alfalfa-bromegrass-lespedeza pastures, each pasture being grazed for 3 to 4 days and rested for 5.5 weeks; 4 complete rotations were done during a 168-day grazing season. (2) lambs and ewes were moved every 2 days, and 3 c ... | 1975 | 1238039 |
| [changes in the serum proteins in lambs experimentally infected with haemonches contortus]. | infected were experimentally eight lambs with larvae of haemonchus contortus. the test lambs were divided into two groups and were given each, by groups, 2500 and 5000 h. contortus larvae. prior to infection and on the 10th, 20th, 30th, 40th and 50th day following it electrophoretic studies on the blood serum were performed. results showed that certain quantitative changes in the protein fractions took place. they consist in the drop of the albumin and the rise of the globulin fractions. | 1975 | 1239856 |
| the efficacy of thiabendazole against the arrested larvae of some trichostrongylidae and chabertia ovina in sheep. | the activity of thiabendazole at 100 mg/kg was tested against the arrested larvae of ostertagia spp, haemonchus contortus, trichostrongylus axei, nematodirus spp and chabertia ovina in natural infections, in 10-month-old lambs. the result, assessed by means of worm counts, showed the treatment to be very effective. | 1976 | 1257622 |
| the ecology of the free-living stages on haemonchus contortus. | | 1976 | 1260414 |
| the passive transfer of humoral immunity from sows infected with hyostrongylus rubidus (hassal and stiles, 1892), the red stomach worm, to their offspring and its significance in the conferring of protective immunity. | sows repeatedly infected with large single doses of third stage infective hyostrongylus rubidus larvae show an anamnestic circulating agglutinin response to the parasite as detected by the passive haemagglutination reaction. at farrowing the circulating antibody level dropped, whereas the colostral agglutinating antibody level increased for a period of a few hours. the predominant class of immunoglobulin which had agglutinating activity against h. rubidus was igg. offspring which had suckled the ... | 1976 | 1262052 |
| haemonchus contortus infection in ewes: blastogenic responses of peripheral blood leukocytes to third stage larval antigen. | | 1976 | 1262125 |
| influence of potassium ion and osomtic pressure on development of haemonchus contortus in vitro. | development of infective larvae of haemonchus contortus to the fourth stage in vitro was impaired if the concentration of potassium ion in the medium was 0.26 mm or less. at or below 0.015 mm, development was almost completely stopped. high concentrations of potassium, in solutions with a ratio of sodium to potassium from 150 down to 1.3, were all equally favorable for development, but solutions composed only of salts of potassium were unfavorable. development was impaired by osmotic pressures b ... | 1976 | 1263034 |
| effect of desiccation on the survival of infective haemonchus contorus larvae under laboratory conditions. | when stored in water at 4 and 20 c, respectively, 42 and 36% of free 3rd-stage, infective larvae of haemonchus contortus were alive after 256 days. when stored at -95 c, 73% of the free, desiccated larvae died during the 1st half hour and 80% during the 1st half day; thereafter no more died for 255 days, the duration of the experiment. desiccation protected the larvae against death on storage at temperature below freezing, but it was harmful at temperatures above freezing. h. contortus larvae do ... | 1976 | 1263035 |
| efficacy of p-toluoyl chloride phenylhydrazone against gastrointestinal helminths in ovines. | a new anthelmintic candidate, p-toluoyl chloride phenlylhydrazone, was administered to lambs in a paste formulation. the efficacy of this drug was determined at dose rates of 20, 30, 40, and 50 mg of active ingredient per kilogram of body weight. helminths expelled by these dosages included haemonchus contortus, ostertagia circumcicta, trichostrongylus colubriformis, t. axei, nematodirus filicollis, cooperia curticei, strongyloides papillosus, oesophagostomum columbianum, bunostomum trigoncephal ... | 1976 | 1263040 |
| a possible relationship between haemonchosis and haemoglobin polymorphism in merino sheep in kenya. | it is known that sheep show polymorphism for haemoglobin in that three phenotypes (hba, hbb and hbab) are normally found. since it has been suggested, on the basis of haematological values, that hba type sheep are more able to survive in haemonchus contortus endemic environments, a preliminary study was conducted on the performance of set-stocked merino ewes and lambs in relation to their haemoglobin phenotypes. the results provided some evidence that, in merino sheep at least, those with hba ... | 1976 | 1265360 |
| resistance of selected lines of haemonchus contortus to thiabendazole, morantel tartrate and levamisole. | | 1976 | 1279076 |
| 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 |
| efficacy of moxidectin against an ivermectin-resistant strain of haemonchus contortus in sheep. | the efficacy of moxidectin was determined against ivermectin-susceptible and resistant strains of haemonchus contortus. at the onset of the trial, 40 lambs were each infected with 5000 third stage larvae of one of two strains of haemonchus contortus. the lambs were randomly sorted into eight treatment groups 28 days post-infection and were treated as follows: group 1, susceptible strain with no treatment; group 2, resistant strain with no treatment; group 3, susceptible strain treated with 0.2 m ... | 1992 | 1502793 |
| comparison of anthelmintic control programs for sheep in virginia. | haemonchus contortus is the most serious parasitic problem encountered by sheep producers in southwestern virginia. four anthelmintic control programs for grazing lambs were tested. group tr received monthly sc injections of ivermectin (200 micrograms/kg of body weight). group si received the same dose of ivermectin at 0, 3, 6, 9, and 12 weeks after the start of the grazing season. group sl was given levamisole (8 mg/kg, po) 0, 3, 6, 9, and 12 weeks after the start of the grazing season, and gro ... | 1992 | 1506250 |
| efficacy of moxidectin, nemadectin and ivermectin against an ivermectin-resistant strain of haemonchus contortus in sheep. | the efficacies of ivermectin, nemadectin and moxidectin were evaluated when administered orally to lambs infected with either a susceptible laboratory strain of haemonchus contortus or a strain reported to be resistant to ivermectin. groups of 24 dorset cross cheviot cross suffolk lambs were infected with either the susceptible or resistant strain of h contortus and allocated to treatment groups according to their faecal egg counts 27 days after infection. one day later the lambs were dosed oral ... | 1992 | 1514227 |
| controlled tests on activity of contemporary parasiticides on natural infections of helminths in lambs, with emphasis on strains of haemonchus contortus isolated in 1955. | ten controlled tests were done between 1972 and 1989, in lambs on pasture, evaluating activity of fenbendazole (fbz; 5 mg/kg of body weight), oxfendazole (ofz; 3.5 and 10 mg/kg), oxibendazole (obz; 10 mg/kg), pyrantel pamoate (prt; 25 mg of base/kg), and thiabendazole (tbz; 44 and 50 mg/kg) against natural infections of helminths, with emphasis on 2 strains (a and b) of haemonchus contortus. strain a was phenothiazine-susceptible and strain b was phenothiazine-resistant when isolated in 1955. fo ... | 1992 | 1539921 |
| interaction between the nematode-destroying fungus arthrobotrys robusta (hyphomycetales) and haemonchus contortus infective larvae in vitro. | in an in vitro trial, the effect of the nematode-destroying fungus arthrobotrys robusta on haemonchus contortus infective larvae was evaluated in petri dishes containing corn meal agar. after seven days incubation at 25 degrees c, 92.33% (+/- 4.1) predation was recorded. | 1992 | 1561755 |
| levamisole-resistant haemonchus contortus in goats. | | 1992 | 1566537 |
| localization of immunoglobulin-containing cells in the abomasum of sheep following infection with haemonchus contortus. | abomasal cannulation followed by serial collection of biopsies was used to study the kinetics of appearance of iga-, igg1-, igg2- and igm-containing cells in the abomasum of sheep following infection with haemonchus contortus. very few immunoglobulin-containing cells (icc) were found in the abomasum of sheep before infection. following h. contortus infection, there were increased numbers of icc in the submucosa of the abomasum. seven days after infection, the numbers of iga-, igg1- and igm-conta ... | 1992 | 1570678 |
| cloning and sequence comparisons of four distinct cysteine proteases expressed by haemonchus contortus adult worms. | three new members of a developmentally regulated cysteine protease gene family of the parasitic nematode haemonchus contortus have been isolated and characterized. one of the new genes, ac-3, was found to be linked in tandem to the previously characterized ac-2 gene. nucleotide sequence analyses revealed that the first 90 amino acids of ac-3 are organized into four exons, similar to the situation in ac-2. a cdna that appears to be a near full-length copy of the ac-3 gene was isolated using the p ... | 1992 | 1574079 |
| gut-specific and developmental expression of a caenorhabditis elegans cysteine protease gene. | a caenorhabditis elegans cysteine protease gene fragment, amplified by pcr using conserved eukaryotic protease gene sequences as primers, was used as a probe to isolate cdna and genomic clones. the genomic clone, which had a coding sequence of 987 bp interrupted by 2 small introns, was physically mapped to the middle of linkage group v. the predicted amino acid sequence of the mature c. elegans cysteine protease was homologous to those of other eukaryotic cysteine proteases, particularly to that ... | 1992 | 1574082 |
| effects of dietary molybdenum on nematode and host during haemonchus contortus infection in lambs. | the addition of molybdenum (0.05 mmol kg-1 dry-matter) to the diet of lambs given a trickle infection of haemonchus contortus larvae (500 third stage larvae d-1 over six weeks) reduced mean faecal egg counts (epg) from 3952 to 2312 +/- 402 by 32 days (p less than 0.02) and greatly reduced the mean number of worms recovered from the abomasum 14 days after infection ceased (907 compared with 4167: p less than 0.01). infection reduced haemoglobin concentrations less in lambs given molybdenum althou ... | 1992 | 1585080 |
| a comparison of superoxide dismutase (sod, ec:1.15.1.1) distribution in gastro-intestinal nematodes. | an examination of the distribution of superoxide dismutase (sod) activities in whole worm homogenates from six gastro-intestinal nematodes, at different life-cycle stages, demonstrated that the third larval stages of each species contained notably more activity than the corresponding adults. significant sod activities were detected in culture fluids following in vitro maintenance of third and fourth larval stage and adult trichostrongylus vitrinus and teladorsagia circumcincta (formerly ostertag ... | 1992 | 1587685 |
| field evaluation of an albendazole intraruminal capsule against benzimidazole-resistant haemonchus contortus. | | 1992 | 1595176 |
| 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 |
| 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 |
| seasonal variations in the numbers of trichostrongylid nematode eggs and their larvae in the faeces of farmed goats in malaysia. | faecal worm egg counts of goats from two farms in penang island, west malaysia, were monitored over a period of 14 months. the faecal egg count pattern followed that of total rainfall. the humid tropical environment was favourable for the development of various species of trichostrongylid nematodes, namely haemonchus contortus, trichostrongylus spp., oesophagostomum spp. and cooperia spp. generally, h. contortus was observed to be the predominant species, more so in the monsoon months of the yea ... | 1992 | 1615628 |
| 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 |
| 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 |
| resistance to ivermectin by haemonchus contortus in goats and calves. | efficacy of ivermectin on susceptible or resistant populations of the parasitic nematode haemonchus contortus was determined in cattle and goats held in a barn. goats were each infected with 3000 infective, ivermectin-susceptible or -resistant h. contortus larvae on day 0 and reinfected with 2000 infective larvae on day 24. goats were treated orally with 600 micrograms kg-1 ivermectin on day 31. no significant differences were detected in blood packed cell volume (pcv) or total protein (tp), pre ... | 1992 | 1639573 |
| no adaptation of haemonchus contortus to genetically resistant sheep. | a composite population of haemonchus contortus was established with larvae from seven diverse sources, then maintained in merino sheep bred to have either increased or decreased resistance to haemonchus. after five, seven and 14 parasite generations, the two resulting lines of parasites were used to infect sheep from the increased resistance line, an unselected control line and the decreased resistance line. line of sheep had a highly significant effect on average faecal egg counts 4 and 5 weeks ... | 1992 | 1639574 |
| differential stability of the benzimidazole (bz)-tubulin complex in bz-resistant and bz-susceptible isolates of haemonchus contortus and trichostrongylus colubriformis. | the binding of [3h]mebendazole ([3h]mbz) to tubulin from bz-susceptible (bz-s) and bz-resistant (bz-r) isolates of haemonchus contortus and trichostrongylus colubriformis was investigated using charcoal extraction and gel filtration techniques. the amount of [3h]mbz bound at infinite free ligand concentration (bmax) was significantly reduced for the bz-r isolate compared with the bz-s isolate in both species when assayed by charcoal extraction. however, bmax was increased to comparable levels fo ... | 1992 | 1639577 |
| 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 |
| 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 |
| 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 |
| 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 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| local eradication of haemonchus contortus using closantel. | | 1991 | 1755790 |
| 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 |
| 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 |
| 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 |
| 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 |
| [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 |