Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| physiological and microbiological changes in the abomasum of sheep infected with large doses of haemonchus contortus. | the ph, po2 and the number of viable bacteria per ml of abomasal fluid were recorded before and after administering large doses of infective larvae of h. contortus to sheep. highly significant increases were observed in the ph, in numbers of viable bacteria and in the proportion of oxygen-sensitive bacteria in the abomasal fluid during the first 10 to 14 days of infection. at the same time a decrease in the abomasal fluid po2 was recorded. subsequently a slow recovery of ph, po2 and bacterial nu ... | 1987 | 3611432 |
| efficacy of fenbendazole-medicated feed blocks against gastrointestinal nematode infections in calves. | an anthelmintic trial was conducted to determine the efficacy of fenbendazole (fbz) incorporated into two types of feed blocks given daily for 3 or 10 days to calves naturally parasitized with gastrointestinal nematodes. each treated calf consumed 5 mg of fbz/kg of body weight. the fbz was greater than 99% effective in removing adults of haemonchus contortus, ostertagia ostertagi, o lyrata, cooperia punctata, c pectinata, c onchophora, trichostrongylus axei, bunostomum phlebotomum, and oesophago ... | 1987 | 3605803 |
| [benzimidazole-resistant haemonchus contortus in sheep in west germany]. | 1987 | 3593194 | |
| epidemiology of gastrointestinal nematodes of sheep and goats in haryana, india. | epidemiological studies on some gastrointestinal nematodes of sheep and goats in karnal, ambala and rohtak districts of haryana (india) revealed that haemonchus contortus and trichostrongylus spp. were responsible for parasitic gastroenteritis in these hosts. the adult parasites persisted in the host throughout the year and there was no indication of hypobiosis. the maintenance of the parasite population depended on a continuous cycle of infection between the host and the pasture. the agroclimat ... | 1987 | 3590608 |
| vaccination of young lambs by means of a protein fraction extracted from adult haemonchus contortus. | lambs aged 48-150 days which had been injected with extracts enriched in a functional antigen (contortin) obtained from adult haemonchus contortus developed specific circulating antibodies and were less susceptible to haemonchosis when challenged 1 month later with a single dose of 20,000-25,000 infective 3rd-stage larvae. sera from 18 out of a total of 19 lambs injected with the extract contained precipitating antibodies to 2-5 components of the extract. none of these lambs died. the one extrac ... | 1987 | 3588016 |
| parasites in sheep grazing on kikuyu (pennisetum clandestinum) pastures in the winter rainfall region. | regular worm counts were done post-mortem on sheep that had grazed on kikuyu pastures at the elsenburg research station near stellenbosch, a winter rainfall region. major species were trichostrongylus colubriformis, trichostrongylus axei, while ostertagia circumcincta was usually present in large numbers. minor species were haemonchus contortus, nematodirus spathiger, dictyocaulus filaria, oesophagostomum venulosum, trichuris spp., chabertia ovina and larvae of the arthropod oestrus ovis. muelle ... | 1987 | 3587925 |
| [microecological characterization of parasitic nematoda present in goats of arid zones of venezuela]. | goats from the venezuelan northern arid zones were found infested by the following nematodes: haemonchus contortus, trichostrongylus axei, t. colubriformis, cooperia curticei, oesophagostomum columbianum, skrjabinema ovis y trichuris globulosa. the shannon-weaver index of diversity values oscillated between 0.045 and 1.73 bits (means = 1.16 +/- 0.24 bits). the maximum value of montly diversity ranged from 1 to 2.80 bits (means = 2.49 +/- 0.28 bits) and the equitability ranged from 0.045 to 0.67 ... | 1986 | 3587000 |
| repeatability of ovine faecal egg counts and blood packed cell volumes in haemonchus contortus infections. | 1987 | 3583550 | |
| partial protection of lambs against haemonchus contortus by vaccination with a fractionated preparation of the parasite. | florida native lambs, less than 6 months of age, were successfully vaccinated against haemonchus contortus with a high mol. wt fraction (greater than 30,000 daltons) derived from a somatic extract of h. contortus larvae (sel) and excretions and secretions (es) of larvae isolated during in vitro development from the infective 3rd to 4th stage. a 59% reduction in adult worm numbers was obtained in vaccinates compared to naive lambs following challenge. the protection in vaccinated lambs was simila ... | 1987 | 3564350 |
| comparison of ivermectin and thiabendazole for treatment of naturally occurring nematode infections of goats in kenya. | the anthelmintic activity of thiabendazole (tbz) at 88 mg kg-1 and ivermectin at 0.2 mg kg-1 was examined in goats with naturally-acquired nematode infections. in one experiment, a herd of 450 does was treated with tbz or ivermectin at 4-week intervals for 9 months and efficacy was measured by reduction in faecal egg counts after each treatment. in a second experiment, 100 kids were treated with ivermectin and effectiveness measured at 2 and 4 weeks after treatment by comparison of their egg cou ... | 1987 | 3564349 |
| changes in lipids and free fatty acid fractions in adult haemonchus contortus during incubation in vitro. | adult haemonchus contortus (rud., 1803) has been investigated for its ability to utilize lipids with regard to the total lipids, sterols, free fatty acids, acylglycerols and phospholipids produced during incubation in vitro. all these components exhibit extensive fluctuations, decreasing at some times and increasing at others, thus indicating both biosynthesis and utilization. also, changes in fatty acid components of total lipids have been analyzed by gas liquid chromatography. these observatio ... | 1987 | 3564346 |
| comparison of inhibition of polymerisation of mammalian tubulin and helminth ovicidal activity by benzimidazole carbamates. | the correlation between the inhibition of hatching of haemonchus contortus eggs and inhibition of mammalian tubulin polymerisation by benzimidazole carbamates has been investigated. the hatching process was observed to be independent of the biomass (eggs plus debris) over a 6-fold range and the early (e1-e3) stages of egg development, but was dependent on the concentration of co-solvent (dmso) and time of incubation. benzimidazole carbamates with strong inhibitory activity against mammalian tubu ... | 1987 | 3564338 |
| the periparturient rise in fecal egg counts in three strains of florida native ewes and its value in predicting resistance of lambs to haemonchus contortus. | 1986 | 3528003 | |
| evaluation of three formulations of fenbendazole (10% suspension, 0.5% pellets, and 20% premix) against nematode infections in cattle. | anthelmintic efficacies of 3 formulations of fenbendazole were evaluated in cattle naturally parasitized with nematodes: a 10% oral suspension, 0.5% pellets as a top dressing on feed, and a 20% premix. all formulations of fenbendazole were greater than 99% effective in removing adults of haemonchus contortus, ostertagia spp, cooperia spp, and oesophagostomum radiatum. fenbendazole was greater than 96% effective in removing adults of strongyloides papillosus and greater than 85% effective in the ... | 1986 | 3516024 |
| effects of anthelmintics on haemonchus contortus (nematoda: trichostrongylidae). | the review summarizes and evaluates recent information about the effects of anthelmintics on haemonchus contortus. the topic is discussed under the headings effects of drugs on the absorptive surfaces, effects of drugs on metabolism, effects of drugs on the neuromuscular system, effects of drugs on developmental stages, anthelmintic efficacy, and resistant strains. possible future lines of work are suggested in the conclusions. | 1986 | 3511606 |
| [ecoepidemiology of haemonchus contortus bahiensis, ecotype present in sheep of arid zones of venezuela]. | the frequency distribution of female haemonchus contortus bahiensis grisi, 1974 in sheep from venezuelan arid zones is 15.32% for the type with vulvar flap, 51.6% for the vulvar-knob and 33.07% for smooth type. a shannon-weaver diversity index corresponding to 1.44 bits was calculated for these forms with similarities in the general size, egg-size and in the number of the longitudinal cuticular ridges. an aggregated kind of distribution in the host population according to the k parameter of a ne ... | 1987 | 3507572 |
| systemic release of a mast cell proteinase following nematode infections in sheep. | an enzyme-linked immunosorbent assay (elisa) for sheep mast cell proteinase (smcp) has been developed. concentrations of smcp in homogenates of abomasal tissue from parasite-immune sheep (341 micrograms smcp/g tissues) were raised when compared to those in normal (non-infected) abomasa (0.145 micrograms smcp/g tissue). smcp was not detected in sera from normal animals challenged with haemonchus contortus but was present (less than 1.0 ng smcp/ml) in sera from 8/11 immune sheep 2 h after intra-ab ... | 1987 | 3479741 |
| changes in the response of haemonchus contortus eggs to the ovicidal activity of thiabendazole during the course of infection. | hatching rates and susceptibility to thiabendazole were studied on haemonchus contortus eggs collected after either a single, a challenge or a trickle infection of sheep with a non-resistant strain. considerable changes were observed both in hatching rates and lc50 values for thiabendazole during the course of infection. peaks in lc50 suggested that a susceptible strain can produce eggs at least tolerant and perhaps slightly resistant at some days pi even without any previous contact with anthel ... | 1987 | 3451681 |
| further investigation of the primary mechanism of benzimidazole resistance in haemonchus contortus. | 1987 | 3440696 | |
| the anthelmintic efficacy of netobimin against naturally acquired gastrointestinal nematodes in sheep. | the broad-spectrum anthelmintic efficacy of netobimin (sch 32481, schering corporation) was evaluated using 30 cross-bred spring lambs with naturally acquired infections of gastrointestinal nematodes. three groups of 10 animals each were allotted into either control (given a tap water drench as a placebo) or 7.5 and 20 mg kg-1 dosage groups (given the netobimin as an oral drench). seven to fourteen days post-treatment, animals were necropsied and nematodes recovered by standard techniques. exami ... | 1987 | 3439008 |
| lipid biosynthesis from 14c-glycerol in haemonchus contortus (nematoda: trichostrongylidae), in vitro. | 1987 | 3434509 | |
| the genetics of resistance and resilience to haemonchus contortus infection in young merino sheep. | 1987 | 3429127 | |
| serial passage of haemonchus contortus in resistant and susceptible sheep. | a recently isolated field strain of haemonchus contortus was passaged through resistant (repeatedly reinfected) and susceptible (immunosuppressed) sheep for six and nine generations, respectively. infectivity of the resulting serially passaged strains was not significantly different when tested in groups of 1-year-old susceptible sheep. | 1988 | 3420791 |
| immune exclusion of haemonchus contortus larvae in sheep: dose dependency, steroid sensitivity and persistence of the response. | naive and immune sheep, treated with anthelmintic, challenged directly into the abomasum and killed 48 hours later were used to examine the steroid sensitivity, persistence and dose dependency of immune mechanisms which result in the failure of incoming haemonchus contortus larvae to establish (immune exclusion). immune exclusion was almost totally abolished by corticosteroid treatment, the mean percentage of larvae establishing in the mucosa of immune sheep was 1.4 per cent of the challenge inf ... | 1988 | 3406527 |
| laboratory selection of haemonchus contortus for resistance to ivermectin. | the eighth generation of adult haemonchus contortus, selected by subjecting infected pairs of sheep to suboptimal ivermectin treatment once per generation from parent (p; bbh isolate) through f7 (iv-a; selected isolate), required an approximate 4-fold increase in the ivermectin dose to produce 95% efficacy compared with its contemporary parent isolate. in a dose titration experiment the dose-response curve of the drug pressure-derived isolate, iv-a, was significantly (0.02 less than p less than ... | 1988 | 3397823 |
| regulation of haemonchus contortus populations in sheep: mortality of established worms. | 1988 | 3372130 | |
| a routine diagnostic assay for the detection of benzimidazole resistance in parasitic nematodes using tritiated benzimidazole carbamates. | resistance to benzimidazoles (bzs) in parasitic nematodes has recently been shown to be due to a reduction in the ability of bzs to bind the structural protein, tubulin, in resistant isolates. based on these observations the development and standardisation of a routine diagnostic assay has been undertaken by measuring the binding of tritiated mebendazole to crude supernatants of l3 larvae. the assay is rapid, requiring less than 2 h, and is robust, highly reproducible and sensitive to minor chan ... | 1988 | 3369079 |
| the population biology of the parasitic stages of haemonchus contortus. | the population biology of the parasitic phase of the haemonchus contortus life-cycle is discussed within the context of a mathematical model of those processes which regulate population density. parasite death is assumed to be attributable to at least three processes: failure of the 3rd-stage larvae (l3) to exsheath following ingestion, failure to become established following exsheathment (immune exclusion), and mortality of 4th- and 5th-stage worms on the mucosal surface. the proportion of worm ... | 1988 | 3362575 |
| epidemiology of ovine helminthiasis in haryana, india. | tracer lambs were used to study the pasture contamination with infective stages of helminth parasites during one annual cycle in a subtropical climate. post-mortem worm counts indicated that low infections with haemonchus contortus occurred throughout the year except in june. however, twenty five or more h. contortus per lamb were recorded in january, april, may and august. trichostrongylus colubriformis infection was detected throughout the year and 150 or more worms per lamb were recorded duri ... | 1988 | 3354055 |
| interactions between the predacious fungus arthrobotrys oligospora and third-stage larvae of a series of animal-parasitic nematodes. | interactions between the predacious hyphomycete arthrobotrys oligospora and third-stage larvae of nine animal-parasitic nematodes were tested in vitro. the trap-inducing capabilities of the ruminant trichostrongylus cooperia oncophora, c. curticei, haemonchus contortus and ostertagia ostertagi and of equine cyathostomes were almost comparable to those of free-living soil nematodes, and significantly higher than those of the porcine oesophagostomum dentatum and oe. quadrispinulatum and of the mur ... | 1988 | 3347992 |
| anthelmintic activity of continuous low doses of fenbendazole into the rumen of sheep. | fenbendazole (fbz) was continuously infused for 30 days into the rumen of 103 lambs which had mature or developing benzimidazole-susceptible or thiabendazole-resistant haemonchus contortus and susceptible trichostrongylus colubriformis infections. ovicidal, larvicidal and adulticidal activities were exhibited against benzimidazole-susceptible and benzimidazole-resistant h. contortus worms by fbz at a dose level of greater than or equal to 0.2 mg kg-1 body weight day-1. reasonably consistent high ... | 1988 | 3347991 |
| two field strains of haemonchus contortus resistant to rafoxanide. | two field strains of haemonchus contortus, one from pretoria on the highveld and the other from white river in the lowveld of the transvaal, showed pronounced resistance to rafoxanide at a dosage rate of 7.5 mg/kg live mass per os. both of these strains originated from kikuyu pastures under irrigation. resistance in south africa to rafoxanide and other anthelmintics, namely, closantel, ivermectin and the benzimidazoles is reviewed. it is concluded that apart from avoiding farming practices where ... | 1987 | 3306550 |
| [benzimidazole resistance in haemonchus contortus in a south german sheep herd]. | 1987 | 3297604 | |
| the effect of haemonchosis and blood loss into the abomasum on digestion in sheep. | 1. an experiment was conducted to determine the effect of the abomasal parasite, haemonchus contortus, on the pattern of digestion and nutrient utilization in merino sheep. there were three groups of sheep: infected with h. contortus (300 larvae/kg live weight) (n 5), sham-infected by transferring blood from the jugular vein to the abomasum, and uninfected (control) sheep (n 9) which were fed daily rations equal to amounts consumed by 'paired' animals in the two other treatment groups. a diet co ... | 1988 | 3257884 |
| selection of ivermectin-resistant trichostrongylus colubriformis in lambs. | a mixed population of haemonchus contortus, teladorsagia circumcincta and trichostrongylus colubriformis was passed for four generations through lambs. in successive passages and on day 6 (d6), lambs were dosed subcutaneously with ivermectin at 100, 200, 250 and 225 micrograms kg-1 body weight, respectively. no larvae of h. contortus were recovered after the first passage and following the third drug exposure only t. colubriformis was present. larvae of the selected strain of t. colubriformis de ... | 1988 | 3245107 |
| a field evaluation of benzimidazole and nonbenzimidazole drugs in a herd of dairy goats. | a study was conducted to investigate the efficacy of six anthelmintics in a herd of dairy goats. pretreatment larval cultures indicated that the goats were infected with haemonchus contortus and trichostrongylus colubriformis. three separate treatment regimens were administered. in each trial, mature nonlactating goats were allocated into two treatment groups and a control group. treatment groups received thiabendazole (tbz) or levamisole (lev), mebendazole (mbz) or fenbendazole (fbz), and moran ... | 1988 | 3225804 |
| larval development test for detection of anthelmintic resistant nematodes. | the growth, using freshly cultured escherichia coli with ampicillin or heat-treated lyophilised e coli as a food source, of the larvae of the mouse nematode nematospiroides dubius and the infectivity of resulting third stage larvae were determined. concentrations of e coli between 0.5 and 1 mg dry weight ml-1 permitted optimal larval development for both n dubius and trichostrongylus colubriformis. development of larvae of susceptible and cambendazole-resistant strains of haemonchus contortus in ... | 1988 | 3222553 |
| influence of dietary protein on the pathophysiology of haemonchosis in lambs given continuous infections. | mixed-sex groups of three-month-old finn dorset and dorset horn lambs were given complete diets containing either high or low protein. a trickle infection with haemonchus contortus of 200 larvae, given three times a week, began one month later for a 17 week period. erythrokinetic, metabolic, digestibility and balance studies were conducted with the male lambs during weeks 12 to 14 of the infection. clinical signs of haemonchosis became evident only in the low protein diet group. the infection wa ... | 1988 | 3222552 |
| hypergastrinaemia of sheep infected with haemonchus contortus. | radioimmunoassay of plasma gastrin has shown that a hypergastrinaemia occurs in yearling sheep, after infection with 10(6) infective third stage larvae of haemonchus contortus. plasma gastrin concentrations began to rise two to four days after infection, that is, at about the same time as, or slightly before, the abomasal ph was observed to increase. | 1988 | 3222544 |
| resistance of young lambs to haemonchus contortus infection, and its loss following anthelmintic treatment. | 1988 | 3220652 | |
| infection with haemonchus contortus in sheep and the role of adaptive immunity in selection of the parasite. | 1988 | 3220647 | |
| the effect of immunosuppression with dexamethasone on haemonchus contortus infections in genetically resistant merino sheep. | the effect of immunosuppression with the glucocorticosteroid, dexamethasone, on the susceptibility to haemonchus contortus infection of a highly resistant merino genotype was investigated. higher faecal egg counts, larger worm burdens and heavier worms were recorded in immunosuppressed wethers. the characteristic globule leucocyte infiltrate in the abomasum of resistant wethers (12-month-old castrated males) was absent in immunosuppressed animals. treatment with dexamethasone abolished differenc ... | 1988 | 3217128 |
| lymphocyte phenotypes in the abomasal mucosa of sheep infected with haemonchus contortus. | lymphocyte subpopulations in the abomasal mucosa of worm-free and parasitized sheep were assessed in situ. a preponderance of t-lymphocytes, with approximately equal numbers of cells expressing cd5, cd4 and cd8 antigens, was found. most of the lymphocytes expressing cd8 lacked cd5. using a panel of 15 monoclonal antibodies to ovine leucocyte antigens, abomasal lymphoid follicles in the mucosa were shown to resemble lymph node follicles phenotypically. abomasal epithelial cells contained major hi ... | 1988 | 3217127 |
| in vitro response of haemonchus contortus larvae harvested during different times of the patent period to anthelmintics. | three commercially available ruminant anthelmintics and an investigational drug were evaluated for effects on the motor function/motility of third stage (ensheathed) haemonchus contortus. helminth ova were collected at one, five, nine and 13 weeks during the patent period, cultured to the third larval stage and assayed for sensitivity to four different drugs. all four drugs (100 and 10 micrograms ml-1) significantly affected the motility of third stage h contortus larvae cultured from eggs passe ... | 1988 | 3194601 |
| the influence of cryopreservation on a benzimidazole-resistant isolate of haemonchus contortus conditioned for inhibited development. | larvae of a fenbendazole (fbz)-selected, benzimidazole-resistant strain of haemonchus contortus were conditioned for inhibited development during 7 weeks at 15 degrees c. sheep raised nearly worm-free were infected with nonfrozen larvae (l3). larvae from the same batch were exsheathed and cryopreserved over liquid nitrogen for 1 year, and another group of sheep was infected with the same dose of these l3 larvae after thawing. egg hatch assays for all sheep were done between 21 and 30 days post i ... | 1988 | 3194369 |
| size of inoculum dose regulates in part worm burdens, fecundity, and lengths in ovine haemonchus contortus infections. | density-dependent factors frequently have been shown to regulate population parameters of free-living and parasitic helminths. to test the effects of various infection levels of haemonchus contortus on fecundity and worm size, lambs were inoculated with 3,000, 10,000, and 30,000 infective larvae. daily eggs per gram (epg) and daily total fecal production per lamb were monitored continuously. worms were collected from abomasa on 6, 15, 22, and 30 days postinfection (pi). female worms were smaller ... | 1988 | 3193336 |
| haemonchosis in sheep and goats in sierra leone. | the incidence of haemonchosis in sheep and goats in sierra leone showed a seasonal variation with a high peak in the dry season (october to january) and a low one from march to may. mean relative densities were significantly higher in young hosts and showed two peaks, a high one from august to december and a low one from april to june while the mean relative densities of old hosts were low and exhibited an irregular seasonal pattern with no defined peaks. the peak seasons in young hosts coincide ... | 1988 | 3192917 |
| evaluation of haemonchus contortus infections in sexually intact and ovariectomized ewes. | three experiments were conducted to investigate experimentally the occurrence of periparturient nematode egg rise in ewes and the hormonal modulation of haemonchus contortus infections. in the first experiment, fall-bred and winter-bred pregnant (n = 4 and 14, respectively) and nonpregnant (n = 5 and 29, respectively) ewes were treated with anthelmintic and were pastured together on fields that were contaminated with h contortus. three weeks before lambing, all ewes were placed in concrete pens; ... | 1988 | 3189989 |
| field observations on the control of ovine parasitic gastroenteritis in south-east england. | three worm control strategies, on a commercial farm in south east england, were monitored parasitologically for a grazing season. three peaks of larval infection in june, late august and late october/early november occurred on paddocks grazed by dosed ewes and lambs on a new ley (preventive strategy). lambs dosed and moved on to a hay aftermath in july (evasive strategy), had a mean egg count of 2090 by late august, attributable to infection with haemonchus contortus. three weekly drenching of l ... | 1988 | 3188346 |
| resistance of field strains of haemonchus contortus to ivermectin, closantel, rafoxanide and the benzimidazoles in south africa. | after a first description in 1975 of a strain of haemonchus contortus resistant to the benzimidazole anthelmintics in south africa, further strains of the same species developed resistance to rafoxanide and closantel, and a strain of ostertagia species became resistant to the benzimidazoles. recently five further strains of h contortus have been found which show resistance to these anthelmintics. of these, four showed varying degrees of resistance to ivermectin and one was resistant to three ant ... | 1988 | 3176284 |
| the effect of dexamethasone on a single and a superimposed infection with haemonchus contortus in sheep. | 1988 | 3170067 | |
| the effect of selenium supplementation on immunity, and the establishment of an experimental haemonchus contortus infection, in weaner merino sheep fed a low selenium diet. | immunity in 12 weaner merino sheep fed a low selenium (se) diet (low se sheep) was compared with that in 10 matching sheep fed the same diet but each given an intraruminal se pellet (high se sheep), while the sheep were housed in individual, sheltered pens. all sheep were challenged with killed brucella abortus cells (days 0 and 28), rabbit red blood cells (days 0, 7 and 28) and corynebacterium pseudotuberculosis toxoid (days 0 and 28), and serum antibody titres were measured weekly for 8 weeks ... | 1988 | 3138968 |
| placental transfer of specific antibodies during ovine congenital toxoplasmosis. | the passage of non-toxoplasma antibodies from dam to fetus through damaged placenta was studied in sheep inoculated with toxoplasma gondii. six ewes were inoculated with chicken globulins and leptospira bacterins 2 months before oral inoculation with toxoplasma gondii oocysts. ewes were euthanatized between 42 and 62 days after t gondii inoculation. antibody titers against chicken globulins, leptospira spp, haemonchus contortus, sarcocystis spp, and t gondii were measured in the maternal and fet ... | 1987 | 3105371 |
| field trials with closantel and haemonchus contortus in sheep in papua new guinea. | sheep treated once with closantel at 7.5 or 15.0 mg/kg and grazing with untreated sheep remained free of haemonchus contortus for at least 4 to 5 weeks and 6 to 7 weeks respectively after treatment. when the whole flock was treated with 15.0 mg/kg, h. contortus began to become re-established 7 to 8 weeks later. maximum benefit of the residual anthelmintic effect of closantel against h.contortus was obtained only when all sheep in the flock were treated; it took 10 weeks longer for h.contortus to ... | 1988 | 3056375 |
| incorporation of carbon from 14c-labelled precursors into major chemical fractions of haemonchus contortus in vitro. | 1986 | 3034006 | |
| haemonchus contortus: lipid biosynthesis from 14c-labelled palmitic acid and sodium bicarbonate. | 1986 | 3034005 | |
| parasites as stressors: plasma cortisol responses of goats infected with the stomach worm haemonchus contortus to exogenous corticotropin (acth). | ten male, juvenile pigmy goats of similar age and weight were allocated randomly to two groups. goats in one group were each inoculated with 20,000 infective larvae of haemonchus contortus. the other group served as uninfected controls. goats were housed together, and precautions were taken to avoid the creation of differential, between group, stressogenic circumstances. body weights, nematode egg production, hematocrits, and clinical signs were monitored over a 61-day period following inoculati ... | 1987 | 3031870 |
| haemonchus contortus: effect of ph and temperature on some dehydrogenases. | 1985 | 2940824 | |
| anthelmintic resistance by haemonchus contortus to ivermectin in brazil: a preliminary report. | 1989 | 2929090 | |
| post-mortem changes in the abomasal mucosae of sheep infected with haemonchus contortus compared with those in uninfected sheep. | progressive post-mortem changes were observed, with fibre optic endoscopy, in the abomasum of uninfected sheep and sheep infected with h. contortus. loss of epithelial cells was observed 14 to 16 min after death in the uninfected sheep. the loss exposed the underlying lamina propria. this loss became more widespread as the time after death increased. epithelial cell loss was observed earlier (as early as 6 min after death) in the infected sheep. three of the infected sheep also displayed dispers ... | 1989 | 2918107 |
| the physiology of infection with nematodes: the role of intracellular ph in the development of the early parasitic stage. | 1. h2co3, the host's signal which induced (less than 25 min) the ca2+-dependent development of the first parasitic stage of haemonchus contortus, produced a diphasic change in the phi (less than 30 min), measured with 5,5-dimethyl-2,4-oxazolidinedione, in the infective stage. the intensity of the diphasic change was related to the [h2co3] and so to the efficiency of the stimulus for development. 2. mes and hepes buffers induced a rapid rise in phi of infective stages in step with pho. ortho-and ... | 1987 | 2890466 |
| transcuticular solute movement in parasitic nematodes: relationship between non-polar solute transport and partition coefficient. | the rate constants (k) for steroid transport across the isolated cuticle of ascaris suum were, linearly related to partition coefficients (p) of steroids in model solvents. the slope of log p vs log k for an isolated cuticle was closest to unity for the more polar solvents, octanol and ether, suggesting that the barrier to steroid movement across the cuticle has partition properties similar to these solvents. the transcuticular movement of steroids into intact adult a. suum and infective larvae ... | 1986 | 2874926 |
| no association between the ovine leucocyte antigen (ola) system in the australian merino and susceptibility to haemonchus contortus infection. | a genetic analysis has been made of the ovine leucocyte antigenic (ola) system in australian merinos. the animals consisted of sires, dams and their progeny. the typing data were consistent with previous findings of a high degree of polymorphism. at least two closely linked loci with several alleles at each are necessary to explain the data. no evidence was found for an association between ola types and three measures of susceptibility to infection by the blood-sucking parasite haemonchus contor ... | 1989 | 2807725 |
| controlled dosage titration of febantel paste in naturally parasitized cattle. | a controlled anthelmintic trial was conducted to determine the efficacy of febantel paste (45.5%) at dosages of 2.5, 5.0, 7.5, and 10.0 mg/kg in calves harboring natural gastrointestinal nematode infections. dosages of 5.0, 7.5 and 10.0 mg of febantel/kg of body weight were greater than 96% effective in removing adults of haemonchus contortus, ostertagia spp, cooperia spp, and oesophagostomum radiatum. the 2.5 mg/kg dosage was considered suboptimal because of low efficacy against ostertagia and ... | 1989 | 2802334 |
| lack of reversion of a benzimidazole resistant strain of haemonchus contortus after six years of levamisole usage. | the resistance level of haemonchus contortus was studied on a farm where benzimidazole resistance had been detected in 1980 and where, since 1982, only levamisole had been used for worm control. egg development tests gave ld50 values of 0.18, 0.19 and 0.21 microgram ml-1 thiabendazole for samples taken from ewes in 1988 compared with 0.21 microgram ml-1 in 1981. studies on sheep experimentally infected with larvae cultured from the faeces of these ewes confirmed the continued resistance of h con ... | 1989 | 2799086 |
| effects of irrigation on appearance and survival of infective larvae of goat gastro-intestinal nematodes in guadeloupe (french west indies). | in guadeloupe (french west indies), faeces from naturally infected goats were deposited during the dry season on three plots, irrigated with long (plot a) or short herbage (b) and non-irrigated with long herbage (c). microclimatic data and the evolution of l3 population size in faeces, on soil surface and on herbage were followed over a period of 26 days. the initial nematode egg population was comprised of 58% haemonchus contortus (hc), 25% trichostrongylus colubriformis (tc) and 17% oesophagos ... | 1989 | 2777463 |
| efficacy of levamisole against immature and mature nematodes in goats with induced infections. | anthelmintic efficacy of levamisole against induced infections with 7- and 21-day-old haemonchus contortus, ostertagia circumcincta, trichostrongylus axei, and t colubriformis was evaluated as an oral drench in goats. group 1 (n = 8) was not treated, group 2 (n = 8) was given 3.96 mg of levamisole/kg of body weight, group 3 (n = 8) was given 7.92 mg of levamisole/kg, and group 3 (n = 7) was given 11.88 mg of levamisole/kg. efficacy against all worms was low in goats given 3.96 mg of levamisole/k ... | 1989 | 2774328 |
| development and survival of free-living stages of gastrointestinal nematodes of sheep and goats on pasture in the nigerian derived savanna. | four grass plots were sequentially contaminated with goat faeces containing known numbers of unembryonated eggs of predominantly haemonchus contortus and trichostrongylus spp. between october 1982 and april 1983. four other plots were similarly contaminated with sheep faeces between february and may 1987. an additional plot was repeatedly contaminated with sheep faeces from february to april 1987. populations of free-living stages in faeces and of infective larvae (l3) in the herbage were subseq ... | 1989 | 2773307 |
| the epidemiological control of nematodes in new england lambs. | epidemiological control of nematodes in weaned lambs in new england was investigated over three grazing seasons (n = 58, n = 52 and n = 62 lambs, respectively). spring prophylactic treatment, clean pasture and mid-summer treat-and-move to hayfield strategies were compared to traditional fall treatments (control). in these studies when lambs were weaned prior to grazing, the most abundant nematodes were nematodirus sp. under these conditions, where only low levels of haemonchus contortus were pre ... | 1989 | 2766746 |
| motility response of levamisole/benzimidazole-resistant haemonchus contortus larvae. | electronic measurements of the motility of third stage larvae of a susceptible and a levamisole/benzimidazole-resistant strain of haemonchus contortus were made after incubation in solutions of anthelmintics for 24 h. results confirmed the resistance to benzimidazoles, but failed to show differences in response to levamisole. visual observations of paralysis of first and third stage larvae in solutions of levamisole also failed to show significant differences between the two strains. the tests a ... | 1989 | 2763445 |
| efficacy of nitroxynil against a benzimidazole-resistant strain of haemonchus contortus in sheep. | 1989 | 2763432 | |
| experimental haemonchus contortus infections in guinea pigs. | approximately 40% of exsheathed haemonchus contortus larvae administered to guinea pigs established in the stomach and developed into fourth stage larvae. most worms were then lost between 5 and 7 days after infection and the guinea pigs were resistant to a second infection. haemorrhage, oedema and infiltration with inflammatory cells, especially eosinophils, developed in the stomach wall of infected guinea pigs and reactive hyperplastic changes occurred in the gastric lymph node. h. contortus i ... | 1989 | 2759770 |
| colorimetric assay for the detection of benzimidazole resistance in trichostrongyles. | a modified version of the aphid tile-test, which is used to detect insecticide resistance in single adult aphids that are resistant or susceptible to organophosphate or carbamate insecticides, was used to compare the levels of non-specific esterases in strains of the trichostrongyle nematodes haemonchus contortus, ostertagia circumcincta and trichostrongylus colubriformis which were known to be resistant or susceptible to benzimidazole (bz) anthelmintics. this colorimetric assay has shown that t ... | 1989 | 2740631 |
| seasonal prevalence of gastrointestinal nematodes of goats in pernambuco state, brazil. | during each of 36 1-month periods from april 1979 to march 1982, 3-4 goats selected from typical farms were necropsied and examined for gastrointestinal nematodes. the goats were male, 12 months old, born on the farm and raised without any anthelmintic application. at the beginning of each month, from april 1981 to march 1982, three 12-month-old male goats shown to be free of gastrointestinal nematodes after anthelmintic treatment were grazed with a flock of naturally infected goats (tracer goat ... | 1989 | 2728324 |
| haemonchus contortus: infectivity and resistance to benzimidazoles. | 1989 | 2728285 | |
| parasites of south african wildlife. iii. helminths of common reedbuck, redunca arundinum, in natal. | twenty-six common reedbuck, redunca arundinum, were shot in pairs at monthly intervals for 13 consecutive months in the himeville region of natal. ten nematode species, 2 cestodes and 1 trematode were recovered from these animals. cooperia yoshidai was both the most numerous and most prevalent worm and peak burdens occurred during summer. thirty-one reedbuck, killed at different intervals in various localities within the st. lucia reserve, harboured between 4 and 11 nematode species, 1 cestode a ... | 1989 | 2726193 |
| the problem of escalating resistance of haemonchus contortus to the modern anthelmintics in south africa. | during the past decade in south africa there has been a continual increase in sheep of strains of gastrointestinal helminths resistant to the modern anthelmintics. five strains of haemonchus contortus are described in this paper. despite the fact that 2 of the 5 strains were tested for susceptibility only to ivermectin, a total of 10 instances of resistance were found. four of the 5 strains were resistant to ivermectin, 2 to closantel, 2 to rafoxanide and 2 to the benzimidazoles. one of these st ... | 1989 | 2726192 |
| a preliminary evaluation of factors affecting an experimental system for vaccination-and-challenge with haemonchus contortus in sheep. | a preliminary evaluation of factors affecting an experimental system for vaccination-and-challenge with haemonchus contortus in sheep. international journal for parasitology 19: 169-175. studies were made with haemonchus contortus in sheep to ascertain the influence of a range of factors in the domain of the host, the parasite or the vaccine on the formulation of protocols for vaccination-and-challenge to be used in identifying protective immunogens. the results corroborate earlier findings that ... | 1989 | 2722389 |
| helminth parasites of intermingling axis deer, wild swine and domestic cattle from the island of molokai, hawaii. | helminth infections of axis deer (cervus axis), wild swine (sus scrofa) and domestic cattle (bos taurus) were studied among intermingling herds on the puu-o-hoku ranch, molokai, hawaii. twenty-four species of helminths were collected from the 10 deer, 10 swine and 10 cattle. capillaria bovis, cooperia punctata, haemonchus contortus and trichostrongylus axei infected both axis deer and cattle, whereas gongylonema pulchrum infected both axis deer and wild swine. none of the species of helminths oc ... | 1989 | 2716106 |
| changes in anthelmintic resistance status of haemonchus contortus and trichostrongylus colubriformis exposed to different anthelmintic selection pressures in grazing sheep. | this experiment was designed to study, over a 5-year-period, the effect of different frequencies of treatment with three different anthelmintic groups, namely, benzimidazoles, levamisole and ivermectin, and different frequencies of alternation between them, on existing levels of anthelmintic resistance in the nematode parasites haemonchus contortus and trichostrongylus colubriformis of grazing sheep. no evidence of ivermectin resistance emerged, even in suppressively treated groups. likewise, h. ... | 1989 | 2707967 |
| south african field strains of haemonchus contortus resistant to the levamisole/morantel group of anthelmintics. | a strain of haemonchus contortus from the pietermaritzburg district of natal was found to be resistant to levamisole (geometric mean efficacy 76.5%), morantel (41.9%), the benzimidazoles (oxfendazole: 33.7%) and rafoxanide (82.0%), but apparently fully susceptible to closantel and disophenol. in the case of ivermectin, a mean of 5.2% of the h. contortus was not removed at a dosage of 200 micrograms kg-1 live mass. a second strain of h. contortus, from amsterdam in the south-eastern transvaal, sh ... | 1989 | 2696916 |
| purification of a 44 kilodalton protease which mediates the ecdysis of infective haemonchus contortus larvae. | we have characterized and purified a parasite protease which mediates the ecdysis of haemonchus contortus, and at least several other ruminant trichostrongyles. the protease, with an apparent approximate molecular weight of 44,000, is a zinc metalloprotein which hydrolyzes several large protein substrates in in vitro assays. in vivo and in biological assays on isolated second molt cuticles this protease hydrolyzes a specific circular region of the second stage cuticle which results in removal of ... | 1989 | 2651914 |
| light and scanning electron microscopy of the ecdysis of haemonchus contortus infective larvae. | during the second ecdysis of ruminant trichostrongyles, a region of the second molt cuticle is digested by a 44-kda zn-metalloprotease. we have examined this digestion process by light and scanning electron microscopy (sem). the substrate region of the cuticle appeared, during the ecdysis process, as an indented ring at the 20th cuticular annulus coincident with the anterior terminus of the lateral alae. continued digestion of the cuticle resulted in holes in the ring region that expanded until ... | 1989 | 2647956 |
| availability of infective larvae of parasitic nematodes of sheep grazing on kikuyu (pennisetum clandestinum) pastures in the winter rainfall area. | thirteen groups of 4 south african mutton merinos grazed for 4 weeks with the flock on kikuyu pastures and were slaughtered for total and differential worm counts at necropsy. subsequently 12 groups of 8 week tracers grazed on the pastures and were killed for worm counts post mortem. the following were present in most sheep: teladorsagia (syn. ostertagia) circumcincta, trichostrongylus axei, trichostrongylus colubriformis, dictyocaulus filaria and oesophagostomum venulosum. haemonchus contortus, ... | 1989 | 2626260 |
| comparison of three in vitro techniques to estimate benzimidazole resistance in haemonchus contortus of sheep. | three in vitro assays to detect benzimidazole resistance, namely, the egg-hatch assay, tubulin-binding assay, and a larval-development assay, were evaluated by estimating the level of benzimidazole resistance in three field isolates of haemonchus contortus compared with a susceptible reference strain. comparisons were also made with estimates of benzimidazole resistance of the three field strains obtained from an in vivo controlled anthelmintic efficacy test. all three in vitro tests showed simi ... | 1989 | 2617826 |
| cuticle collagen genes of haemonchus contortus and caenorhabditis elegans are highly conserved. | several genes and partial cdnas encoding cuticle collagens have been isolated from the sheep parasitic nematode haemonchus contortus. dna sequencing and southern blot hybridization studies reveal that h. contortus collagens comprise a large family of related, but non-identical genes. the genes appear to be dispersed throughout the genome. the predominant size of collagen mrna in molting worms was found to be between 1.0 and 1.2 kb. the one complete gene that was sequenced contains two short intr ... | 1989 | 2615789 |
| [the helminth fauna of the gastrointestinal tract of young cattle in northwest germany]. | ten unmedicated animals of a controlled anthelmintic trial were used to analyse the present gastrointestinal helminth fauna of young cattle from the northwest of germany. this survey done in august revealed ostertagia ostertagi to represent the most prevalent and abundant species followed by cooperia oncophora and nematodirus helvetianus. o. lyrata, o. leptospicularis, c. zurnabada, c. punctata, trichostrongylus axei, haemonchus contortus, bunostomum phlebotomum, capillaria bovis and trichuris d ... | 1989 | 2598802 |
| cross-immunity between haemonchus contortus and trichostrongylus colubriformis in sheep. | cross-protective immunity between the nematode parasites, haemonchus contortus and trichostrongylus colubriformis, was examined in sheep vaccinated with irradiated larvae of either species. secondary immunological responsiveness stimulated in this manner protected only against challenge infection with the species used for vaccination. significant cross-protective immunity was not observed. titres of serum antibody to an extract of adult but not infective larval t. colubriformis reflected the spe ... | 1989 | 2592138 |
| the cuticular proteins from free-living and parasitic stages of haemonchus contortus--i. isolation and partial characterization. | 1. cuticles were isolated from the adult males, adult females, the second molt (2m) sheath from the infective larvae (l3(2m)), and the parasitic third stage (l3) of the sheep parasite haemonchus contortus by a combination of mechanical disruption and detergent treatment. 2. the 2me soluble cuticular proteins from adult males contained 4 or 5 major protein bands with molecular weights ranging from 100 to 56 kd with the most prominent band at 56 kd. the cuticular proteins from adult females were s ... | 1989 | 2591199 |
| efficacy of three broad-spectrum anthelmintics against gastrointestinal nematode infections of goats. | groups of 10 goats, harbouring both naturally acquired and experimental infections of gastrointestinal nematodes, were drenched with either levamisole (5 mg kg-1), albendazole (3.8 mg kg-1) or parbendazole (15 mg kg-1), or remained untreated. haemonchus contortus was the numerically dominant infection, with strongyloides papillosus, trichostrongylus colubriformis and oesophagostomum columbianum also present. at 5-6 days post-treatment, goats were killed and necropsied. post-mortem worm counts sh ... | 1989 | 2588471 |
| effects of exogenous progesterone and/or prolactin on haemonchus contortus infections in ovariectomized ewes. | reproduction can alter the course of ovine nematodiasis; fecal nematode egg concentrations often increase near lambing and throughout lactation, a phenomenon referred to as the periparturient rise. to identify the host mechanisms that might link these disparate events, i.e. lactation and the fecundity of gastrointestinal trichostrongyles, ovariectomized ewes were injected daily with progesterone and/or prolactin, or saline. progesterone treatment commenced 20 days before inoculation with haemonc ... | 1989 | 2588470 |
| restriction fragment length patterns of dna from parasitic nematodes of sheep. | high molecular weight dna obtained from sheep parasitic nematodes haemonchus contortus, ostertagia circumcincta and trichostrongylus colubriformis, was digested with various restriction endonucleases. digestion with eco r1 produced the most informative pattern of repeat sequence bands. h contortus adult or larval dna produced bands of 2.7, 3.0 and 1.4 kb. o circumcincta adult or larval dna had common 2.7 and 1.4 kb bands with adult specific bands of 2.2 and 0.9 kb and a larval specific 2.08 kb b ... | 1989 | 2564211 |
| identification and preliminary characterization of cuticular surface proteins of haemonchus contortus. | cuticular surface antigens of the xl3 and l4 stages of haemonchus contortus have been studied by surface labeling and immunological techniques. live worms were labeled with 125i and extracted with sodium dodecyl sulfate (sds) followed by sds + 2-mercaptoethanol. the sds-soluble surface proteins of xl3s and l4s were found to consist of relatively few major species. the pattern of labeled polypeptides was distinctive for each developmental stage. these proteins are refractory to digestion by bacte ... | 1989 | 2552312 |
| gastrointestinal nematode infections of goats in a sub-tropical and humid zone of india. | twelve hundred and twenty-eight goats (capra hircus l.) from a sub-tropical and humid zone of india were examined for gastrointestinal nematodes. the species encountered in the region were: haemonchus contortus, bunostomum trigonocephalum, oesophagostomum columbianum, trichuris globulosa, o. aspersum, and t. ovis. the overall infection rate was 86.8%. among various species found, h. contortus emerged as the most prevalent, although b. trigonocephalum and o. columbianum were also significantly in ... | 1989 | 2529697 |
| effects of the chitin synthesis inhibitor diflubenzuron on development of ascaris suum and haemonchus contortus. | the potential of the chitin synthesis inhibitor diflubenzuron (dfb) to alter the development of the parasitic nematodes (ascaris suum and haemonchus contortus was investigated. dfb given orally (10 mg kg-1 per day for 30 days) to sheep inoculated with h. contortus infective larvae did not prevent the establishment of adults or affect fecal egg output. however, there was a significant (greater than 90%) decrease in the number of infective larvae recovered from fecal cultures derived from lambs ha ... | 1989 | 2505433 |
| parasite-specific t cell responses of sheep following live infection with the gastric nematode haemonchus contortus. | helper t cell lines recognizing antigen in the context of mhc class ii molecules were generated from peripheral blood mononuclear cells (pbmc) of sheep undergoing a primary or secondary infection with the nematode parasite haemonchus contortus. the lines were used to identify 15-18, 25-29, 70-80 and greater than 100 kd immunodominant parasite larval antigens fractionated by sds-page under reducing conditions. non-specific mitogenic activity in the antigen fractions was not detected. during prima ... | 1989 | 2479901 |
| haemonchus contortus: a simple procedure for purifying surface proteins from third- and fourth-stage larvae. | surface proteins were solubilized from exsheathed third (xl3)- and fourth (l4)-stage larvae of haemonchus contortus by a one-step extraction procedure involving brief heat treatment of the worms in the presence of buffer and 100 mm sodium chloride. surface proteins also could be preferentially extracted from xl3s, but not from l4s, by heating the worms briefly in 1% sodium dodecyl sulfate. the major proteins extracted by these procedures were similar in molecular weight to those detected by surf ... | 1990 | 2404783 |
| haemonchus contortus: evidence that the 3a3 collagen gene is a member of an evolutionarily conserved family of nematode cuticle collagens. | rabbit antisera were raised against an 18 amino acid-long peptide that corresponds to the predicted sequence of the carboxy-terminal, nontriple helical region of the haemonchus contortus 3a3 collagen gene. this sequence is highly conserved and diagnostic for members of the col-l collagen family, which includes the 3a3 gene. we find that these antisera react predominantly with multiple, high molecular weight (greater than 68 kda) proteins on western blots of whole worm extracts. the number and mo ... | 1990 | 2404780 |
| haemonchus contortus with low inhibited development in sheep from the highveld of zimbabwe. | the abomasa of sheep grazing on natural pastures in the highveld of zimbabwe were examined for haemonchus contortus. of 304 abomasa, 213 (70%) harboured h. contortus. the worm burden increased during the rains to reach the peak in february-march. this was followed by a decline with low worm loads throughout the dry season. the fourth stage larvae (l4) accounted for 1-7% of the total h. contortus population, except during july and august when they comprised 22 and 54% of the worm burden, respecti ... | 1990 | 2399655 |
| experimental haemonchus contortus infection in three breeds of sheep. | nine- to 10-month-old florida native, st. croix and dorset/rambouillet sheep were infected with haemonchus contortus. the primary infection was terminated by anthelmintic treatment 9 weeks later and animals were then reinfected with h. contortus. dorset/rambouillet sheep showed higher fecal egg counts and decreased packed cell volumes and plasma protein levels compared with the other two breeds during the primary infection. however, no breed differences were found in total worm burdens in either ... | 1990 | 2399644 |