Publications

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
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
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 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
infection with haemonchus contortus in sheep and the role of adaptive immunity in selection of the parasite.		1988	3220647
resistance of young lambs to haemonchus contortus infection, and its loss following anthelmintic treatment.		1988	3220652
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
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
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
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
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
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
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
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
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
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
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
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
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
regulation of haemonchus contortus populations in sheep: mortality of established worms.		1988	3372130
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
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
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
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
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
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
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
haemonchus contortus: infectivity and resistance to benzimidazoles.		1989	2728285
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
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
efficacy of nitroxynil against a benzimidazole-resistant strain of haemonchus contortus in sheep.		1989	2763432
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
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
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
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
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
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
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
anthelmintic resistance by haemonchus contortus to ivermectin in brazil: a preliminary report.		1989	2929090
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
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
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
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
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
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
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
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
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
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
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
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
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
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
[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
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
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
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
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
failure of young goats to acquire resistance to haemonchus contortus.	two experiments were carried out to investigate the acquisition by goats of resistance to haemonchus contortus. in experiment 1, five saanen wethers reared worm-free and averaging 5 1/2 months of age at the start of the experiment, were dosed with 200 h. contortus infective larvae three times per week for 10 weeks (approximately 23 infective larvae/kg mean initial liveweight/week) and then given anthelmintic treatment. each goat and an equal number of worm-free controls were then challenged with ...	1989	16031502
multigeneric resistance to benzimidazole anthelmintics in sheep.	benzimidazole resistance involving several gastrointestinal nematode genera on a single sheep farm in new zealand is reported for the first time. a controlled slaughter trial showed that at the recommended dose rate of 12.5 mg/kg, mebendazole had efficacies of 0, 60, 66, 90, 54 and 38% against haemonchus contortus, ostertagia spp., nematodirus spp., intestinal trichostrongylus spp., strongyloides spp. and oesophagostomum venulosum, respectively. the relevance of such multigeneric resistance to p ...	1989	16031521
low susceptibility of the laboratory-reared afghan pika, ochotona rufescens rufescens to haemonchus contortus.		1990	2280496
influence of dietary protein on the immune responsiveness of sheep to haemonchus contortus.	twenty helminth-free lambs were fed diets containing either 169 g crude protein (cp) kg-1 dry matter (dm) or 88 g cp kg-1 dm from the age of seven months. one month later five lambs from each dietary group were vaccinated against haemonchus contortus by the oral administration of 10,000 irradiated larvae on two occasions, four weeks apart. four weeks following the administration of the second dose of irradiated larvae both the vaccinated and unvaccinated lambs were exposed to an experimental inf ...	1990	2300701
pepsinogen types in worm-free sheep and in sheep infected with ostertagia circumcincta and haemonchus contortus.	pepsinogen isolated from the plasma of dorset wethers with abomasal burdens of ostertagia circumcincta was found to have the same proportions of three zymogen subtypes as that isolated from the plasma of merino wethers with abomasal burdens of haemonchus contortus. it appears that the underlying pathophysiological response which causes increased plasma pepsinogen concentrations during abomasal parasitism may be the same irrespective of the breed of sheep or species of parasite.	1990	2300702
scanning electron microscopy of the sheathed infective larva and parasitic third-stage larva of haemonchus contortus (nematoda: trichostrongyloidea).	scanning electron microscopy was used to describe the infective and parasitic third-stage larvae of haemonchus contortus, the large stomach worm of ruminants. infective larvae are ensheathed in the cuticle of the second stage, so the descriptions are of the second- and third-stage cuticles. both larval stages had an inner circle of 6 labial papillae, an outer circle of 6 labial papillae and 4 somatic papillae, and lateral amphidial pits. infective larvae (cuticle of the second stage) had the 6 i ...	1990	2319426
closantel resistance in haemonchus contortus from sheep.		1990	2334373
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
the efficacy of netobimin against a benzimidazole susceptible and a resistant strain of haemonchus contortus in sheep in the netherlands.	netobimin was tested for efficacy against haemonchus contortus using 7 groups of 5 parasite-free lambs of six months age. the lambs in group 1 and 2 were infected with 10,000 larvae of a benzimidazole susceptible strain and those in groups 3-7 with the same dose of a resistant strain. the following treatment scheme was applied 21 days after infection: lambs in groups 2 and 4-7.5 mg kg-1 netobimin, in group 5-20 mg kg-1 netobimin, in group 6-5 mg kg-1 oxfendazole and in group 7--3.8 mg kg-1 alben ...	1990	2270650
response to helminth infection of sheep selected for resistance to haemonchus contortus.	lines of merino sheep selected for increased (irh) and decreased (drh) resistance to haemonchus contortus were compared with an unselected (ch) line, after approximately four generations of selection. measurements were recorded on 69 irh, 47 drh and 84 ch animals. following artificial challenge with h. contortus, the irh line had significantly (p less than 0.001) lower faecal egg counts than the ch and drh lines (2730, 12,720 and 17,400 epg, respectively). significant differences (p less than 0. ...	1990	2074125
the epidemiology of helminthosis in small ruminants under the traditional husbandry system in eastern nigeria.	the epidemiology of helminth infections in west african dwarf sheep and goats under the traditional husbandry system prevailing in the derived savanna area of eastern nigeria was studied for 12 months. the infections observed were due to haemonchus contortus (87.1%), trichostrongylus spp. (63.8%), metacestodes of taenia hydatigena (30.2%), oesophagostomum columbianum (22.4%), strongyloides sp. (18.8%), cooperia spp. (17.2%), gaigeria pachyscelis (6.0%), moniezia expansa (6.0%), bunostomum trigon ...	1990	2247944
[principal helminths of small ruminants in ituri (upper zaire)].	from august 1986 to november 1987, about 180 slaughtered sheep and goats were examined at bunia (haut-zaïre) in order to establish the main helminth parasites. seventeen and fifteen species were identified in sheep and goats respectively. the occurrence of stilesia hepatica, oesophagostomum multifoliatum and muellerius capillaris as well as the absence of echinococcus granulosus constituted the original features of this check-list in the area. parasitism the most frequently encountered both in s ...	1990	2369171
effect of haemonchus contortus infection on the clearance of antipyrine, sulfobromophthalein, chloramphenicol, and sulfathiazole in lambs.	a study was made to determine the effect of haemonchus contortus parasitic infection in lambs on the clearance of several iv administered drugs. clearance of sulfobromophthalein or sulfathiazole from the plasma of lambs was unaffected by infection with h contortus. clearance of antipyrine was enhanced by the infection, and thiabendazole treatment did not alter this effect. clearance of chloramphenicol (cap), administered as the succinate ester (caps), was not changed by the infection, but it was ...	1990	2085232
a developmentally regulated cysteine protease gene family in haemonchus contortus.	the nucleotide sequence of a gene encoding a 35-kda thiol protease of the parasitic nematode haemonchus contortus has been determined. the gene, designated ac-2, shares 97% nucleotide sequence identity and 98% amino acid identity with previously characterized ac-1 cdnas encoding the thiol protease. the ac-2 gene spans 8 kb and appears to contain 11 introns, ranging in size from 57 bp to over 5.2 kb. one of the introns interrupts the proposed active site region that is conserved between the h. co ...	1990	2090940
infection of immunosuppressed mice with the abomasal nematode parasite of ruminants, haemonchus contortus.	infective larvae of haemonchus contortus established in mice either immunosuppressed with the corticosteroid, dexamethasone, or the cytotoxic drug, cyclophosphamide, or treated with the histamine h2 inhibitor, cimetidine. infections persisted for as long as the immunosuppressive treatment (7 days) and growth of larvae was similar to that seen in sheep. virtually no larvae survived in untreated mice. accordingly, it would appear that adaptive immunity is an important barrier against primary infec ...	1990	2121657
studies on the presence and release of proteolytic enzymes (proteinases) in gastro-intestinal nematodes of ruminants.	the proteolytic activity of worm homogenates prepared from the third stage larval (l3) and adult stages of the ovine gastro-intestinal nematodes, nematodirus battus, ostertagia circumcincta, trichostrongylus colubriformis, trichostrongylus vitrinus and haemonchus contortus, and the rodent intestinal nematode, nippostrongylus brasiliensis, has been examined using the protein substrates azocasein, azocoll and elastin-orcein. activity detected in third stage larvae was usually higher than that obse ...	1990	2185170
molecular cloning and primary sequence of a cysteine protease expressed by haemonchus contortus adult worms.	we have cloned cdnas encoding a 35-kilodalton cysteine protease that is a major component of protective extracts isolated from blood-feeding haemonchus contortus adult worms. near full-length cdnas for the protease were isolated by immunoscreening an adult worm cdna expression library with a rabbit antiserum prepared against the protein eluted from preparative sds gels and by rescreening the library with oligonucleotide probes. the protein predicted from the nucleotide sequence of the cdnas and ...	1990	2385265
experimental haemonchus contortus infection in three breeds of sheep.	nine- to 10-month-old florida native, st. croix and dorset/rambouillet sheep were infected with haemonchus contortus. the primary infection was terminated by anthelmintic treatment 9 weeks later and animals were then reinfected with h. contortus. dorset/rambouillet sheep showed higher fecal egg counts and decreased packed cell volumes and plasma protein levels compared with the other two breeds during the primary infection. however, no breed differences were found in total worm burdens in either ...	1990	2399644
effect of copper oxide wire particle treatment on establishment of major gastrointestinal nematodes in lambs.	eighty-four 10-week-old lambs were used to investigate the effect of copper oxide wire particle treatment on the establishment of major gastrointestinal nematodes. they were maintained on pasture previously treated to minimise larval contamination. five grams of uniform sized copper oxide wire particles were given orally five days before infection with either 20,000 trichostrongylus colubriformis larvae, 20,000 ostertagia circumcincta larvae or 3000 haemonchus contortus larvae given as three dos ...	1990	2236907
biochemical and immunochemical characterization of 125i-labeled cuticle components of haemonchus contortus.	live haemonchus contortus developmental stages were radioiodinated and then subjected to a stepwise extraction procedure consisting of a buffer extract (with or without detergent) to solubilize putative surface-associated antigenic macromolecules, followed by a detergent/beta-mercaptoethanol (bme) extract to solubilize putative cuticle collagen proteins. a buffer-extracted iodinated 100-kda protein was present in the free-living, infective l3(2m) stage. this labeled protein was released during i ...	1990	2270098
strategies for vaccination against gastro-intestinal nematodes.	a great diversity of gastro-intestinal nematodes parasitise man and his animals. each nematode is antigenically highly complex with distinct developmental stages. the parasites occupy a range of niches in the host gut and have a variety of feeding habits. hosts have evolved only partially successful local immune responses. the host and parasite factors modulating these responses are described. strategies for vaccination are surveyed. it is argued that the best route to successful vaccines will b ...	1990	2132697
strategies for detoxification of aldehydic products of lipid peroxidation in helminths.	crude extracts from a number of helminths including schistosoma intercalatum and fasciola hepatica were able to detoxify known aldehydic products of lipid peroxidation. a major route for alk-2-enal and alka-2,4-dienal detoxification in parasitic helminths was via glutathione conjugation and glutathione transferase appeared to be responsible for the activity. as yet uncharacterised nadph-linked systems may provide an important secondary pathway for detoxification of alk-2-enals and alka-2,4-diena ...	1990	2270103
effect of nilzan and albendazole on the absorptive surfaces of haemonchus contortus (nematoda)--a histoenzymic study.	haemonchus contortus, incubated in 10 micrograms/ml and 50 micrograms/ml concentrations of nilzan and albendazole in tyrode solution were stained for histoenzymatic demonstration of various phosphatases, oxido-reductases and esterases. the intestine showed major alterations after drug treatments. the alkaline phosphatases (akpase), adenosine triphosphatase (atpase), glucose-6-phosphatase, succinic dehydrogenase (sdh), glutamate dehydrogenase (gdh), reduced nicotinamide adenine dinucleotide phosp ...	1990	1963279
changes in liveweight gain, blood constituents and worm egg output in goats artificially infected with a sheep-derived strain of haemonchus contortus.	two groups of goats were dosed with 10,000 and 20,000 sheep-derived strain (sds) larvae of haemonchus contortus respectively. over a period of 42 days goats dosed with 20,000 larvae lost more weight than those dosed with 10,000 larvae. infected goats showed anaemia from about 2 weeks after infection as well as reduced levels of total serum proteins and albumins.	1990	2271911
a larval development test for the detection of anthelmintic resistance in nematodes of sheep.	first stage larvae of a number of species of parasitic nematodes of sheep have been shown to develop to third stage larvae in the presence of a defined medium consisting of earle's balanced salt solution and yeast extract. a larval development test, based on this culture technique, was used as a screen for detecting the presence of anthelmintic resistance in nematodes of sheep. it was found to be sensitive and simple to use and also appeared capable of detecting resistance to any of the main ant ...	1990	2236917
gastro-intestinal nematode infections in a goat breeding farm in north-western sri lanka.	faecal egg counts were used to study patterns of nematode infestation of adult female goats and their offspring according to season, pregnancy and lactation or age on a goat farm (n = 2000) in north-western sri lanka. average rainfall in the area is 825 mm and temperature is between 23 and 33 degrees c throughout the year. the only nematode species present on the farm were haemonchus contortus and oesophagostomum columbianum. in adult females the faecal egg output was not influenced by season an ...	1990	2288007
the seasonal epidemiology of gastrointestinal nematodes in n'dama cattle in the gambia.	from june 1987 to june 1988, a total of 180 n'dama cattle were necropsied to identify and enumerate parasites present, including 39 sick calves and 25 dead calves from local village herds, and 116 adult cattle from a local abattoir. of 175 animals infected with one or more helminths (97%), haemonchus contortus was found in 67% of all necropsied animals, cooperia punctata in 75%, cooperia pectinata in 55%, oesophagostomum radiatum in 71% and bunostomum phlebotomum in 21%. there was a wide range o ...	1990	2238429
the localization of somatostatin-like immunoreactivity in the alimentary tract of the sheep with observations on the effect of an infection with the parasite haemonchus contortus.	cells containing somatostatin immunoreactivity were localized in the alimentary tract of parasite-free sheep by indirect immunocytochemistry, using an antiserum raised to ovine somatostatin. nerve fibres showing somatostatin-like immunoreactivity were identified in the oesophagus, reticulum wall and groove, rumen pillar and wall, omasum sulcus and abomasum. varicose fibres were found in the myenteric plexuses of the duodenum, jejunum, ileum and colon. the greatest distribution of endocrine cells ...	1990	1980195
a novel anthelmintic model utilizing jirds, meriones unguiculatus, infected with haemonchus contortus.	currently, no in vivo laboratory model is available for evaluating anthelmintics against the important ruminant helminth haemonchus contortus. this report outlines a novel anthelmintic assay utilizing immunosuppressed (0.02% hydrocortisone in feed) jirds, meriones unguiculatus, infected with h. contortus. immunosuppressed jirds were inoculated with approximately 1,000 exsheathed infective larvae of h. contortus, treated per os on day 10 postinoculation (pi), and necropsied on day 13 pi. each sto ...	1990	2319415
absence of hypobiosis in abomasal nematodes of sheep and goats in egypt.	a total of 96 abomasa from sheep and goats at the zagazig abattoir, sharkia province, egypt, were examined, during the four climatic seasons from april 1986 to march 1987, for the presence of adult and larval nematodes. adults of trichostrongylus axei were most numerous followed by adult haemonchus contortus. adult ostertagia sp. and parabronema skrjabini were less prevalent. there was no significant difference between sheep and goats in infection rates, but worm burdens of the nematodes other t ...	1990	2238430
specific interaction of benzimidazole anthelmintics with tubulin: high-affinity binding and benzimidazole resistance in haemonchus contortus.	the specific (high-affinity) binding of tritiated benzimidazole [(3h]bz) anthelmintics-mebendazole [(3h]mbz) and oxibendazole [(3h]obz) to, and the specific displacement (inhibition) of these radioligands by unlabelled bzs (oxibendazole, mebendazole, oxfendazole, albendazole, fenbendazole and thiabendazole) from crude tubulin extracts prepared from thiabendazole (tbz)-susceptible (s) or tbz-resistant (r) strains of adult haemonchus contortus, have been examined. the most striking difference betw ...	1990	2325707
development and survival of infective larvae of haemonchus contortus and trichostrongylus colubriformis on pasture in a tropical environment.	a trial to determine the seasonal pattern of egg hatching and larval survival on pasture was carried out in representative wet and dry zones of fiji. fourteen plots were established on parasite-free pasture at each of two sites. one plot at each site was contaminated every month with faeces from naturally infected goats containing a known proportion of haemonchus contortus and trichostrongylus colubriformis eggs. pasture was sampled at regular intervals after contamination and infective larvae i ...	1990	2332275
resistance to benzimidazoles in haemonchus contortus of sheep in tanzania.	this study was undertaken to establish whether resistance to benzimidazole anthelmintics was present in gastrointestinal nematodes of sheep and goats at the university farm of sokoine university of agriculture, morogoro, tanzania. groups of lambs were treated with albendazole at 3.8 mg/kg (recommended dose rate), 5.6 mg/kg and 10.0 mg/kg and a fourth group was untreated. seven days after treatment, faecal egg count reductions (fecr) were found to be 94.3%, 97.6% and 99.3% and 14 days after treat ...	1990	1980804
molecular analysis of selection for benzimidazole resistance in the sheep parasite haemonchus contortus.	the molecular basis for the resistance of the sheep parasitic nematode haemonchus contortus to the benzimidazole (bz) group of anthelmintics was investigated. three bz-susceptible and three resistant populations from different geographical locations were characterized with respect to the egg-hatch assay with thiabendazole (tbz), mebendazole (mbz) binding tests and restriction fragment length polymorphism (rflp) after southern blotting. cloned h. contortus alpha- and beta-tubulin genes were used ...	1990	1981249
special problems of hair goats.	the majority of angora goats in the united states are in texas, although several other states have significant populations. angora goats have unique nutritional requirements, especially for protein, owing to their selection for mohair production. they are typically managed on extensive systems in which nutrition is marginal at certain times of the year. mineral requirements and plant toxicities may vary between regions where angora goats are raised. many toxic plants are unpalatable and a proble ...	1990	2245371
the population biology of the free-living phase of haemonchus contortus.	a deterministic model for the demography of the free-living stages of haemonchus contortus is described. the model consists of three compartments: the pre-infective stages, comprising the eggs and first- and second-stage larvae combined; third-stage larvae in the faeces; and third-stage larvae on the pasture. the mortality (mu j) of each of these stages was a function of temperature (k, where k = (degrees celsius + 30)/100) of the form, mu j = a j exp [alpha j k] + b j exp [-beta j k]. the minim ...	1990	2263426
[the nematode haemonchus contortus: antigenic characterization and immune response in rabbits and sheep].	in the first part of the study, various tissues of l3 larvae and adult haemonchus contortus were examined by indirect fluorescence to investigate their antigenicity. l3 larvae were studied in immunoblots as well. the following tissues contained antigens: the sheath and cuticle of l3 larvae; and the cuticle, muscles, epithelium and glandular tissue of the oesophagus and sheath of the spicules of adult nematodes. on the cuticle of exsheathed l3 larvae, we detected by light-microscope slightly rais ...	1990	2260078
is there a relationship between haemoglobin genotype and the innate resistance to experimental haemonchus contortus infection in merino lambs?	responses to a single or repeated infection with 7000 infective larvae of haemonchus contortus were studied in an experiment using a total of 106 3-month-old lambs with aa, ab or bb haemoglobin (hb) genotypes. results were assessed by faecal egg counts, adult worm counts, haematocrit values, haemoglobin concentrations, total serum protein and serum antibody igg1 and iga elisa titres. none of these parameters showed a strong relationship to the hb type. the prevalence of low responder (greater th ...	1990	2238431
faecal water content and egg survival of goat gastro-intestinal strongyles under dry tropical conditions in guadeloupe.	faeces from naturally infected goats were deposited on a natural grassland during the dry season in guadeloupe (french west indies) at different times throughout the day. the grass was either 7 or 20-30 cm tall. after a period of between several hours and 7 days, the number of viable strongyle eggs and the faecal water content were measured. faecal temperature was recorded continuously. faecal temperature was greater than 40 degrees-45 degrees c at midday and dehydration was rapid between 8 a.m. ...	1990	2352914
characterization of a high-affinity membrane-associated ornithine decarboxylase from the free-living nematode caenorhabditis elegans.	ornithine decarboxylase has been identified and characterized in the free-living nematode caenorhabditis elegans. unlike previously described ornithine decarboxylases, the enzyme activity is membrane-associated and remains in the membrane fraction after treatment with high salt, detergents or phosphatidylinositol-specific phospholipase c. ornithine has an apparent km value of 2.7 microm for ornithine decarboxylase. the enzyme is competitively inhibited by arginine and lysine with ki values of 4. ...	1990	2241895
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