Publications

the abomasal histology of worm-free sheep given primary and challenge infections of haemonchus contortus.	the histological changes in the abomasal mucosa of pairs of worm-free ewes and lambs were compared at various stages after infection and reinfection with 350 haemonchus contortus l3 per kg bodyweight. in terms of worm burdens the ewes were relatively resistant to reinfection compared with the lambs and the histological changes in the abomasum at most stages after infection were more marked in the adult animals. these included increases in the numbers of mast cells, globule leucocytes, eosinophil ...	1984	6543052
anthelmintic efficacy of avermectin b1a and dihydroavermectin b1a against ovine gastrointestinal nematodes in 1977.	in a critical study, 40 female mixed-breed lambs with experimental infections of cooperia spp, trichostrongylus colubriformis, ostertagia circumcincta, t axei, and haemonchus contortus were allocated to 8 groups in 1977. groups 1 and 5 served as controls. groups 2 to 4 were treated orally with avermectin b1a at dosage levels of 25, 50, and 100 micrograms/kg of body weight, respectively. groups 6 to 8 were given oral dihydroavermectin b1a at dosage levels of 50, 100, and 200 micrograms/kg, respec ...	1984	6547280
efficacy of ivermectin against internal parasites of sheep.	ivermectin in an oral formulation was evaluated by the non-parametric method against a wide range of endoparasites of sheep in 15 trials involving a total of 297 sheep. ivermectin at 200 micrograms/kg was more than 80% effective in more than 80% of the treated animals (i.e. class a) against induced infestations of 3rd and 4th stage larvae and adults of chabertia ovina, dictyocaulus filaria, haemonchus contortus (including a benzimidazole-resistant strain), nematodirus spathiger, oesophagostomum ...	1984	6549472
the effect of haemonchus contortus infection on the pregnant and lactating ewe.		1983	6618756
investigation with dexamethasone of the processes which moderate immunity against the nematode, haemonchus contortus, in sheep.	treatment of sheep with the corticosteroid, dexamethasone, was used to investigate some properties of the immunoregulatory process which dampens the expression of protective responses against the abomasal nematode, haemonchus contortus, and which may occur as an adaptation for evasion of host immunity by this parasite. the protective responses released by giving dexamethasone early in infection operated during a series of superimposed infections. accordingly, they may also operate during field e ...	1983	6626053
morphology and histochemistry of the spicules and gubernaculum of haemonchus contortus (nematoda: trichostrongylidae).	a study has been made of the morphological, histological and histochemical characteristics of spicules and gubernaculum in haemonchus contortus (rud., 1803). the correlation coefficients of body length and left and right spicule lengths, left and right spicule lengths, and the distance of barb from the distal end of left and right spicule ends have been found to be statistically significant while the correlation coefficient of body length and gubernaculum length has been found to be non-signific ...	1983	6629205
haemonchus contortus from the vaal ribbok, pelea capreolus, and the bontebok, damaliscus dorcas dorcas, in the bontebok national park.	during a survey of the parasites of antelope in the bontebok national park, swellendam, cape province, specimens of haemonchus contortus with exceptionally long spicules were recovered from 5 out of 8 bontebok, damaliscus dorcas dorcas, and 3 out of 5 vaal ribbok, pelea capreolus, but not from 4 springbok, antidorcas marsupialis. typically, h. contortus has spicules 0,466 +/- 0,085 mm long, but those recovered from vaal ribbok had spicules 0,581 +/- 0,02 mm long and were recovered in large numbe ...	1983	6646659
population dynamics of haemonchus contortus and trichostrongylus spp. in sheep.		1983	6654581
observations on the self-cure reaction and other forms of immunological responsiveness against haemonchus contortus in sheep.		1983	6654583
erythrocyte potassium concentration: a simple parameter for erythropoiesis in sheep infected with haemonchus contortus.	a number of haematological parameters were monitored in eight-month-old merino wethers, six infected with 10,000 haemonchus contortus and 13 controls. blood loss caused by infection was reflected in a decrease in packed cell volume (r = -0.78; p less than 0.001), and was correlated with faecal egg excretion (r = 0.89; p less than 0.001). infected animals showed a decline of serum iron content and increased serum transferrin levels. erythrocyte potassium concentration showed a high correlation wi ...	1983	6665309
stimulatory effects of prostaglandin f2 alpha on faecal egg production in haemonchus contortus infected sheep.	the effect of prostaglandin f2 alpha on the pattern of faecal egg count was tested in 10- to 12-month-old sheep infected with 20,000 haemonchus contortus larvae. prostaglandin was infused intravenously 25, 50 and 75 days after infection for four hours at a rate of 5 micrograms/kg/minute and the egg counts in the faeces were determined daily for 110 days. treatment on days 50 and 75 was followed by a significant rise in egg count lasting 19 and 12 days respectively. this observed rise seems to be ...	1983	6665312
immune exclusion, a mechanism of protection against the ovine nematode haemonchus contortus.	the fate of exsheathed haemonchus contortus larvae injected directly into the abomasal lumen was studied in groups of naive and hyperimmune sheep. within 48 hours of challenge, more than 90 per cent of the larvae were lost from hyperimmune sheep. the larvae had a propensity to associate with the superficial mucus in both groups and, in naive sheep, approximately 50 per cent of the larvae entered glandular tissue within four hours of challenge. by contrast, although initially associated with the ...	1983	6665320
radiolabeling of infective larvae of haemonchus contortus (nematoda: trichostrongyloidea) with 75se-methionine and their performance as tracers in sheep.	haemonchus contortus infective larvae incorporated between 5 and 12 pci/larva for each muci of 75se-methionine added per gram of fecal sediment. thorough admixture of 75se-methionine and fecal sediment was necessary to obtain approximately normal distribution and low variance of individual larval radioactivities. ecdysis induced by treatment with 0.025% hclo in vitro resulted in loss of approximately 40% of the 75se label of infective larvae. loss of 75se by parasitic larvae and adult h. contort ...	1983	6672167
epidemiology of gastrointestinal parasites of awassi sheep in iraq.	studies on the epidemiology of gastrointestinal nematodes of sheep, conducted at two different farms in the baghdad area, in 1979, revealed two peaks in worm egg counts in ewes, one in spring and the other in autumn; the latter coincided with the lambing season. similarly in lambs, two peaks of infection were apparent, but the spring peak was not so well defined. during the hot and dry summer months of iraq, helminthic infection was at a low level. faecal culture for larvae and their identificat ...	1983	6683037
endotube-brush border complexes dissected from the intestines of haemonchus contortus and ancylostoma caninum.	a procedure for the blunt dissection of the syncytial intestine of haemonchus contortus to separate the endotube-brush border complex is described. a similar complex can be obtained from the partially cellular intestine of ancylostoma caninum. the structural features of the complexes from the two sources are compared. the main differences are in the retention of terminal bars by the endotube from a. caninum and in the extent and organization of the microfilaments associated with the basal side o ...	1983	6684761
the effects of transfer factor, parasitic antigen and precipitated immunoglobulin treatments in lambs infected with haemonchus contortus.	significant reductions in adult worm burdens in lambs less than six months old infected with 5000 third stage haemonchus contortus larvae were achieved following the combination of a single transfer factor treatment with multiple parenteral treatments of adult parasitic antigen and precipitated immunoglobulin. specific cellular responses in the abomasa associated with individual treatments were discernible in all the experimental groups and quantitative differences in these responses reflected t ...	1983	6684825
a survey of seasonal changes in nematode faecal egg count levels of sheep and goats in senegal.	a survey of the gastro-intestinal nematodes in domestic sheep and goats of the sahelian zone of senegal was undertaken. their prevalence and the egg production were estimated by faecal egg count in 2234 sheep and 577 goats slaughtered at the dakar slaughterhouse during a 12 month period. the highest prevalence (%) and highest mean egg counts (epg) were recorded at the end of the wet season. amongst the species of nematodes encountered there are two of potential importance: haemonchus contortus a ...	1983	6686379
the effects of dl-tetramisole and rafoxanide on tricarboxylic acid cycle enzymes of haemonchus contortus, in vitro.	various enzymes of the tricarboxylic acid cycle (tca) viz., aconitase (e.c. 4.2.1.3), isocitrate dehydrogenase (e.c. 1.1.1.42), succinate dehydrognease (e.c. 1.3.99.1), fumarate reductase (nadh: fumarate oxido-reductase), fumarase (e.c. 4.2.1.2) and maltate dehydrogenase (e.c. 1.1.1.37) were detected in adult haemonchus contortus (nematoda: trichostrongylidae), in vitro. low activities of aconitase and isocitrate dehydrogenase suggested that the tca cycle has a minor function and the pathway of ...	1983	6686386
in vitro activity of various anthelmintic compounds against haemonchus contortus larvae.	twenty-five known anthelmintic compounds were evaluated in vitro against the highly motile exsheathed non-feeding third-stage of haemonchus contortus larvae. activity was based on lack of motility or death of larvae after 24 h of chemical exposure. six compounds (avermectins, closantel, levamisole, morantel, phenylhydrazone and ticarbodine) were active at a concentration of 100 micrograms cm-3 or less. the most active compounds were avermectins and levamisole. when higher in vitro concentrations ...	1983	6686387
antiparasitic efficacy of ivermectin in naturally parasitized sheep.	sixteen sheep harboring naturally acquired parasitisms were allocated to 1 of 2 treatment groups: (i) sheep given ivermectin in an oral solution at the dosage rate of 200 micrograms/kg of body weight, and (ii) those given the vehicle at a dosage rate of 0.25 ml/kg. all animals were necropsied at 2 weeks after treatment. parasites and percentages of parasitic reductions, as demonstrated in this trial, were: dictyocaulus filaria (99.4%), oestrus ovis first stage instars (100%), trichuris ovis (98. ...	1983	6689112
nematoda: aerobic respiratory pathways of adult parasitic species.	aerobic respiratory pathways have been compared in adult parasitic nematodes, including trichostrongylus colubriformis, nippostrongylus brasiliensis, ostertagia ostertagi, cooperia oncophora, haemonchus contortus, oesophagostomum venulosum, chabertia ovina, dictyocaulus filaria, dictyocaulus viviparus, and ascaridia galli. respiration was measured in both whole worm or tissue homogenates and isolated mitochondrial fractions, and delineated into the mammalian type or alternative respiratory pathw ...	1984	6692887
use of coproantibody measurement to assess the influence of diet on local immune responses of sheep vaccinated against haemonchus contortus.	local antibody responses to challenge with 10,000 normal haemonchus contortus larvae were evaluated in vaccinated and control blackface sheep fed either a high or low protein diet. anti-parasite antibody activity was found in faecal extracts of both vaccinated and control animals after infection. the coproantibody levels showed some correlation with abomasal mucosa antibody levels and faecal antibody activity was mostly associated with iga. the low protein diet reduced local antibody responses i ...	1984	6718823
immunological unresponsiveness of lambs to infection with haemonchus contortus. modulation of responsiveness by exposure to soluble larval antigen.	the in vitro transformation of lymphocytes in the presence of antigen was used to assay the response of lambs to antigens of haemonchus contortus. neither uninfected lambs nor lambs infected with h. contortus up to 9 weeks of age developed in vitro lymphocyte responsiveness to antigen. a slight and transient increase in reactivity was demonstrable in some of the infected lambs when these were reinfected with h. contortus at 26 weeks of age. this lack of responsiveness could be modulated through ...	1984	6720032
immunological unresponsiveness of lambs to infection with haemonchus contortus. effect of infection in the ewe on the subsequent responsiveness of lambs.	specific antigen-induced lymphocyte transformation in vitro and haemagglutinating antibody responses were absent from lambs infected with haemonchus contortus. however, when lambs were injected with soluble third stage larval antigen of h. contortus, given on five occasions during the first 6 weeks of life, specific antigen-induced lymphocyte transformation and haemagglutinating antibodies were induced to the antigen. in particular, a periparturient increased susceptibility to infection and the ...	1984	6720033
control of hypobiotic and benzimidazole-resistant nematodes of sheep.	in studies comprising a total of 117 naturally infected crossbred lambs, it was found that lambs turned out to spring pasture were exposed to immediate infection with overwintered ostertagia, nematodirus, and trichostrongylus spp, but did not acquire haemonchus contortus infection until july. with all species, there appeared to be only one major disease-producing generation of worms per year; it was responsible for serious worm burdens and clinical disease from july onward. high frequencies of h ...	1984	6725108
haemonchus contortus: lipid biosynthesis from c14-labelled acetate and glucose.		1984	6730798
respiratory metabolism and thiabendazole susceptibility in developing eggs of haemonchus contortus.		1984	6735578
glutathione-s-transferase, a possible drug-metabolizing enzyme, in haemonchus contortus: comparative activity of a cambendazole-resistant and a susceptible strain.		1984	6735580
the relevance of in vitro anthelmintic screening tests employing the free-living stages of trichostrongylid nematodes.	the response of the free-living stages of nippostrongylus brasiliensis, nematospiroides dubius, haemonchus contortus, trichostrongylus colubriformis and ostertagia ostertagi to a wide variety of antiparasitic agents in vitro was investigated. all the major broad spectrum veterinary anthelmintics showed good activity against each of these worms with ec50 values varying from about 0.0002 mg/l for certain benzimidazoles and ivermectin to about 6.5 mg/l for febantel. of 22 known narrow spectrum anth ...	1984	6747252
slight resistance to the residual effect of closantel in a field strain of haemonchus contortus which showed an increased resistance after one selection in the laboratory.	on the strength of a complaint of suspected resistance to closantel, a field strain of haemonchus contortus was isolated from sheep on a farm near pretoria and tested for resistance to the remedy, both without exposure to closantel in the laboratory (designated the "unselected" substrain of the parasite) and after a single selection with closantel (called the "selected" substrain). for comparative purpose a few sheep were treated with rafoxanide to ascertain whether the efficacy of this drug was ...	1982	6764253
the role of carbon dioxide in the metabolism of adult haemonchus contortus, in vitro.	adult haemonchus contortus worms simultaneously excrete and fix co2. their initial content of co2 was measured as 4.55 mumoles/100 mg wet weight and their excretion rate in air as 1 mumol/100 mg wet weight/h for at least 4 h. when the worms were incubated either aerobically or anaerobically with 14co2 most of the metabolized radioactivity was associated with propan-1-ol and propionate but small amounts were found in succinate and lactate. no radioactivity was associated with ethanol or acetate, ...	1980	6770322
the glucose metabolism of adult ostertagia circumcincta, in vitro.	adult ostertagia circumcincta from freshly killed sheep were incubated at 39 degrees c in a medium containing inorganic salts, antibiotics and d-[u-14c] glucose. the worms appeared healthy even after incubation for as long as 72 h. all the radioactivity was recovered either within the worms or in the incubation vessel in the form of metabolic products or unmetabolized glucose. incubations were carried out at low oxygen tension except for those in which co2 was measured. these were either aerobic ...	1981	6782539
haemonchus contortus: immunodiffusion patterns of antigens from phenotypically different females.		1982	6800835
effects of two consecutive experimental haemonchus contortus infections on abomasal pepsin and electrolytes and serum pepsinogen and electrolytes of sheep.	pepsinogen, sodium, potassium and chloride concentrations in blood, and pepsin, ph and ionic concentrations in abomasal contents were measured in 4 lambs each fitted with a permanent abomasal cannula infected with 25 000 h. contortus larvae at intervals of 39 days. no significant change in blood sodium, potassium and chloride concentrations occurred after infections while the pepsinogen level increased rapidly to reaching a maximum (600% of control) 7-8 days after infection. this increase was as ...	1981	6805407
glucose metabolism of haemonchus contortus adults: effects of thiabendazole on susceptible versus resistant strain.	analyses of the in vitro glucose metabolism of haemonchus contortus adults have confirmed a complex series of end-products: ethanol, n-propanol, propionate, acetate, and co2 as the major end-products of catabolism. no difference in end-product accumulation was seen between the cambendazole sensitive (bpl) and cambendazole resistant (cr) strains. thiabendazole (5 mm) in vitro depressed ethanol, propanol, acetate, and propionate accumulation by approximately 42% in the bpl strain. however, in the ...	1982	6813445
changes in optical path difference in the oesophageal region and the excretory cells during exsheathment in haemonchus contortus.		1982	6819242
infectivity of haemonchus contortus in sheep after freezing for ten years over liquid nitrogen.		1983	6827445
development of benzimidazole resistance in a haemonchus contortus strain in the netherlands following fenbendazole treatment of ewes at parturition.	in contrast to observations in former years treatment of ewes after parturition with 5 to 7.5 mg/kg fenbendazole was not fully effective in removing haemonchus contortus. comparison of the h contortus populations in the lambs of these ewes and those of untreated ewes later in the year revealed that the treatment resulted in fenbendazole resistance and also in side resistance to other benzimidazoles. though the faecal egg counts of the treated ewes were low, the prophylactic effect of the treatme ...	1983	6836180
changes in resistance in mixed infections of susceptible and benzimidazole resistant strains of haemonchus contortus and trichostrongylus colubriformis passaged in sheep.	benzimidazole resistant strains of haemonchus contortus and trichostrongylus colubriformis were each diluted with equal numbers of their respective susceptible genotypes and passaged in separate worm-free sheep. the progeny of the mixed susceptible and resistant infections were diluted with equal numbers of susceptible genotypes before passaging on two further consecutive occasions in worm-free sheep. in h contortus the amount of thiabendazole required to prevent a 50 per cent egg hatching (lc50 ...	1983	6836181
seasonal fluctuations and hypobiosis of gastro-intestinal nematodes of awassi lambs in iraq.	the results of an epidemiological study involving the estimation of worm counts of gastro-intestinal nematodes of lambs, during the period december 1978 to november 1979, in the baghdad area are reported. ostertagia spp. and trichostrongylus spp. were the most abundant nematodes in the weaned lambs used in this study. ostertagia spp. infection was present throughout the period of observation, the level of infection being the highest during early summer (may-june). trichostrongylus spp. infection ...	1983	6856333
observations on the fumarate reductase system in haemonchus contortus and their relevance to anthelmintic resistance and to strain variations of energy metabolism.	fumarate reductase activity in a thiabendazole-resistant strain of haemonchus contortus was found to be significantly lower than that from a susceptible strain. however, the fumarate reductase activity in a mebendazole-resistant strain did not differ from that in the susceptible strain, even though it was cross-resistant to thiabendazole. published reports of fumarate reductase activity in strains of h. contortus susceptible or resistant to benzimidazoles were reassessed. a second, unrelated aus ...	1983	6877276
ribonucleotide levels in six nematodes, a cestode and a trematode.	the levels of ribonucleotides in the nematodes haemonchus contortus, ostertagia circumcincta, trichostrongylus colubriformis, nippostrongylus brasiliensis, ascaris suum and stephanurus dentatus, the cestode moniezia expansa and the trematode fasciola hepatica were measured by high pressure liquid chromatography. the adenylate charge, atp and total adenine nucleotide levels were in general agreement with those determined enzymatically and with published data. udp and guanine nucleotide levels wer ...	1983	6877282
[resistance to nematodes to anthelmintics].	resistance of nematodes to anthelmintics is being increasingly observed throughout the world in recent years. benzimidazole-resistance of haemonchus contortus is also observed in the netherlands. there are a number of methods to detect resistance to anthelmintics of which only the in vitro techniques can be used to detect resistance in the field. factors such as dosage, frequency of treatment and the time of treatment may affect resistance.	1983	6879576
[observations on the effect of some measures for preventing gastrointestinal helminth infections in sheep].	prophylactic anthelmintic treatment of ewes about parturition has only a negligible effects on the most important species of helminths when the ewes and their lambs are not grazed on clean pasture. haemonchus contortus infections were completely prevented in some cases but usually severe infections occurred. as the build-up of these heavy infections in lambs was slightly delayed in comparison with that in the lambs of untreated ewes, treatment about parturition should still be regarded as useful ...	1983	6879577
pharmacokinetic behaviour and anthelmintic efficacy of 1-n-butyl carbamoyl oxfendazole given by intramuscular injection.	oxfendazole (ofz) was chemically modified to 1-n-butyl carbamoyl ofz (c4-ofz) in an attempt to improve the solubility of ofz and enable it to be administered by injection. after intramuscular injection to sheep and cattle, c4-ofz was metabolised to ofz which resulted in higher plasma ofz concentrations that persisted for a considerably longer period than those observed following administration of ofz orally. the anthelmintic efficacy of injected c4-ofz was tested, in sheep, against strains of tr ...	1983	6880009
a comparison of the effects of dialysed and non-dialysed transfer factor preparations on haemonchus contortus infections in young lambs.	significant reductions in worm burdens were achieved in lambs treated with dialysed transfer factor and challenged with 10,000 haemonchus contortus larvae, when compared with challenged control animals. non-dialysed transfer factor, from the same leucocyte pool, produced no protection, but was successful in reducing worm burdens when given after a primary infection of 1,000 h. contortus larvae with subsequent challenge of 10,000 larvae. while the results confirmed the previously reported inconsi ...	1983	6880013
worm burdens in cows. ii. an analysis of the population of nematodes in the abomasa of adult dairy cows.	over a period of one year, from february 1979-february 1980, the abomasa of four dairy cows were examined each week for the presence of parasitic nematodes. based on the identification of adult male worms, ostertagia ostertagi (94%) and trichostrongylus axei (75%) were the most prevalent species, and haemonchus contortus was absent. total worm burdens varied from zero (one cow) to 100,890. the geometric mean total number was 3011. the geometric mean number of arrested larval stages was 685. of t ...	1982	6890273
haemonchus contortus: egg laying influenced by abomasal ph in lambs.		1982	6891337
gastro-intestinal nematodes in sheep in kashmir.	examination at necropsy of the abomasum and intestinal tract of 62 sheep (including both sexes) of karnah breed, aged one to two years over a period of one year was conducted at handwara, situated in the north-west of kashmir valley. the following species of nematodes were found: haemonchus contortus, trichostrongylus axei, trichostrongylus colubriformis, bunostomum trigonocephalum, chabertia ovina, nematodirus spathiger, skrjabinema ovis and trichuris ovis. infections with trichostrongylus axei ...	1982	6891858
seasonal incidence of helminths in sheep and goats in south mozambique.	the seasonal fluctuations in faecal worm egg counts were studied at monthly intervals for over a year in 20 male sheep and goats on extensive grazing tracts at a farm near maputo, mozambique. larval differentiation from faecal cultures showed that haemonchus contortus and oesophagostomum columbianum were the most prevalent worm species. trichostrongylus colubriformis, cooperia spp., strongyloides papillosus, moniezia spp., paramphistomum spp. and trichuris spp. also occurred. after the onset of ...	1982	6892176
strongyle infections of small ruminants in nigeria.	a survey of strongyle infections was conducted in sheep and goats reared in a traditional extensive husbandry system in two ecological zones of nigeria. one zone had a seasonal pattern of infection. the majority of animals had faecal worm parasite egg counts of below 500 eggs per gram. kids, and lambs younger than 3 months did not carry strongyle worm burdens, and the highest infection rate was found in the 7-12 month age group. a high proportion of small ruminants shed strongyle eggs during the ...	1982	6892178
morphological changes in trichostrongylid eggs after treatment with fenbendazole.	the influence of daily doses of 0.05-0.1 mg fenbendazole/kg body weight on egg development was tested in twenty-seven lambs artificially infected with haemonchus contortus plus trichostrongylus colubriformis or ostertagia circumcincta, as well as in two additional sheep naturally infected with nematodirus spp. atypical eggs were detected before a reduction in the number of eggs. atypical eggs had blastomeres of different sizes and shapes; knot-like, crater-like or bubble-like. in isolated cases ...	1982	6892181
anthelmintic efficacy of 22,23-dihydroavermectin b1 against gastrointestinal nematodes in calves.	anthelmintic activities of 22,23-dihydroavermectin b1 (comprised to greater than or equal to 95% 22,23-dihydroavermectin b1a and less than or equal to 5% 22,23-dihydroavermectin b1b) against gastrointestinal nematodes in calves were evaluated in 2 controlled experiments. infective larvae of haemonchus contortus, ostertagia ostertagi, trichostrongylus axei, t colubriformis, cooperia oncophora, and c punctate were given to 11-week-old calves and oesophagostomum radiatum had been given 21 days earl ...	1981	6895285
anthelmintic efficacy of ivermectin against immature gastrointestinal pulmonary nematodes of calves.	anthelmintic efficacy of ivermectin (greater than or equal to 80% 22,23-dihydroavermectin b1a and less than or equal to 20% 22,23-dihydroavermectin b1b) was evaluated in a controlled experiment against immature nematodes. twenty calves raised to about 8 weeks of age under nematode-free conditions were allocated into 4 groups. infective larvae of haemonchus contortus, ostertagia ostertagi, trichostrongylus axei, t colubriformis, cooperia oncophora, c punctata, oesophagostomum radiatum, and dictyo ...	1981	6896121
oxfendazole: anthelmintic activity in sheep artificially infected with nematodes. results of trials against nine species including benzimidazole-resistant haemonchus contortus.	in a series of 11 trials, in which 281 lambs were artificially infected with 9 species of nematodes, larval anthelmintic tests were carried out to assess the activity of a dose of 5 mg/kg oxfendazole against all 3 parasitic stages of each species. an efficacy of over 99,4% was obtained against all stages of haemonchus contortus, ostertagia circumcincta, trichostrongylus colubriformis, nematodirus spathiger, gaigeria pachyscelis, chabertia ovina and oesophagostomum columbianum with the exception ...	1980	7005443
efficacy of ivermectin against naturally acquired and experimentally induced nematode infections in sheep.	the activity of ivermectin against common nematode parasites of sheep was examined in 2 experiments. in the 1st experiment, 14 sheep with naturally acquired infections were assigned to 2 groups of 7 sheep each. sheep in 1 group were treated with 200 micrograms of ivermectin/kg of body weight and the remainder served as nontreated controls. in the 2nd experiment, 15 sheep with experimentally supplemented infections (including a benzimidazole-resistant strain of haemonchus contortus) were assigned ...	1982	7041712
haemonchus contortus: abomasal transmural potential difference and permeability changes associated with experimental infection in sheep.		1982	7060704
[haemonchosis in lambs and the prophylactic effect of anthelmintic treatment; consequences of sub-therapeutic dosage and the presence of strains of haemonchus contortus resistant to benzimidazoles in the netherlands (author's transl)].		1982	7064137
[observations on the spring rise of faecal strongyle egg counts in goats (author's transl)].	examination of the faeces at regular intervals during the period from february to june 1980 in a group of multiparous dairy goats produced the following results: (a) a marked increase in faecal strongyle egg-counts, (b) haemonchus contortus was the worm mainly causing this increase, (c) differences in faecal egg-counts between dutch white (saanen) goats and toggenburger goats or between groups of goats of different ages were not observed, (d) no differences in faecal egg-counts were observed in ...	1982	7064140
gastro-duodenal motor and transit disturbances associated with haemonchus contortus infection in sheep.	abomasal and duodenal motility was investigated by electromyography in 4 lambs fitted with permanent abomasal and duodenal cannulae and infected twice with 25,000 haemonchus contortus larvae at an interval of 39 days. in addition, abomasal and duodenal ph, flow rate of digesta of the duodenum, and faecal water content were determined. the 80-90 min cycles of antral contractions were shortened for at least 3 weeks after infection. this was accompanied by a 26% increase in the number of duodenal m ...	1982	7070846
benzimidazole resistance in a field strain of haemonchus contortus in the netherlands.		1982	7072124
changes in the flow and composition of gastric lymph in sheep given a primary infection of 10,000 haemonchus contortus.	some aspects of the local immune response to a primary infection with 10,000 haemonchus contortus were studied in five sheep by monitoring changes in the flow and composition of gastric lymph continuously sampled for up to 34 days from the start of infection. increases in lymph flow rates were recorded in four animals at varying times after the start of infection. these were usually associated with an increase in the protein content of the lymph and were considered to be a consequence of inflamm ...	1982	7079599
attempts to immunise sheep against ostertagia circumcincta with irradiated larvae.	mature sheep immunised with two doses of 10,000 irradiated ostertagia circumcincta larvae were only slightly resistant to challenge with a single dose of 10,000 larvae. this slight resistance was abolished if the 'vaccine' worm population was removed one week before challenge. in contrast, seven of eight sheep immunised with irradiated haemonchus contortus larvae were highly resistant to homologous challenge. evidence of some cross protection against challenge with o circumcinta was observed in ...	1982	7089372
evaluation of the cornell-wisconsin centrifugal flotation technique for recovering trichostrongylid eggs from bovine feces.	several variables in the cornell-wisconsin centrifugal flotation technique were studied using helminthologically sterile bovine feces to which known numbers of haemonchus contortus eggs had been added. neither mode of mixing (levigation versus conventional), volume (15-60 ml) of water used for making the feces water suspension nor specific gravity (1.20-1.33) of the sucrose flotation solution affected egg recovery. optimal times for centrifugation at 264 x g of first the feces water and then the ...	1982	7093809
the pathogenesis of a single challenge dose of haemonchus contortus in lambs under six months of age.		1982	7096969
origin of the early digestive disturbances induced by haemonchus contortus infection in lambs.		1982	7103200
studies on haemonchus contortus. vi. attempts to stimulate immunity to abomasal trichostrongylids in merino sheep.	two doses of infective larvae of 20 000 trichostrongylus axei, dosed to merino lambs at an interval of 14 days and subsequently challenged with ostertagia circumcincta, caused a significant reduction (p less than 0.01) in the establishment of 5th and adult stages of the latter. t. axei was unable to protect merino sheep against homologous challenge nor was haemonchus contortus a successful vaccine against challenge with the same species. the vaccinated group showed a reduction (p less than 0,025 ...	1982	7122063
studies on haemonchus contortus. vii. the effect of treatment of trichostrongylus axei prior to challenge with h. contortus.	four-month-old worm-free merino lambs were dosed with 20 000 infective larvae of trichostrongylus axei on day 0 and again on day +14. on day +83 they were treated with mebendazole at 15 mg/kg. all lambs in this group and a further group of 11 worm-free merino control lambs were challenged with 50 000 infective larvae of haemonchus contortus dosed from day +90-day +92. at necropsy 27 and 28 days later there was no significant difference between the worm burdens of the 2 groups. t. axei must be pr ...	1982	7122068
effect of anthelmintic treatment of ewes at parturition and lambs at weaning on the build up of haemonchus contortus populations in lambs in the netherlands.	in two groups of ewes and lambs, grazing pastures which were used respectively by calves and sheep in the previous year, infection with haemonchus contortus was virtually prevented by a single treatment of the ewes with fenbendazole before turning out. in another group, grazing a pasture which was not grazed in the previous year, a delay of approximately eight weeks in the build up of high h contortus burdens in lambs was obtained by this treatment, compared with a group of untreated ewes grazin ...	1982	7134638
effect of removing anthelmintic selection pressure on the benzimidazole resistance status of haemonchus contortus and trichostrongylus colubriformis in sheep.		1982	7134649
time of onset and target of immune reactions in sheep with acquired immunity against haemonchus contortus.		1982	7141783
the response of sheep to parenteral vaccination and immunizing infections against the abomasal nematode, haemonchus contortus.		1982	7141784
the use of faecal egg counts for estimating worm burdens in sheep infected with haemonchus contortus.	clun forest sheep, worm-free from birth, were given a single dose of 20 000 infective larvae of haemonchus contortus. the total number of eggs/day in the faeces was recorded for 21 infections and data on population size, sex ratio and individual worm development were collected from 76 sheep. the female to male ratio was 1.28 +/- 0.07 (s.e.). the relation between increase in worm size and uterine egg content was linear. the number of eggs present in the uteri was found to be an accurate measure o ...	1982	7145469
the effect of ethoxyzolamide, an analogue of insect juvenile hormone, nor-adrenaline and iodine on changes in the optical path difference in the excretory cells and oesophagus during exsheathment in haemonchus contortus.		1982	7160957
enhanced resistance to infection with haemonchus contortus in sheep treated with a corticosteroid.		1982	7160958
haemonchus contortus: the in vitro effects of dl-tetramisole and rafoxanide on glycolytic enzymes.		1982	7160961
the anthelmintic efficacy of artemisia herba-alba against haemonchus contortus infection in goats.	the anthelmintic activity of the powdered shoots of artemisia herba-alba was investigated in experimental haemonchosis in six nubian goats which had been infected with single doses of 800 to 1,000 infective haemonchus larvae. the clinical signs of caprine haemonchosis included inappetence, dullness and soft faeces and were correlated with the pathological findings. none of these changes were observed in four of the six goats following the treatment with 2, 10 or 30 g of artemisia shoots. this su ...	1982	7162537
the effects of treatment with transfer factor, parasitic antigen and precipitated immunoglobulin on the parasitological and histopathological responses in haemonchus contortus infection in lambs under six months of age.		1982	7166633
the trichostrongyloid parasites of sheep in south australia and their regional distribution.	the species of trichostrongyloid nematodes present in 376 sheep from different agricultural regions of the state of south australia were determined. parasites encountered in the abomasum were teladorsagia circumcincta, t. trifurcata, t. davtiani, camelostrongylus mentulatus, haemonchus contortus and trichostrongylus axei. t. circumcincta was the species most commonly encountered, but c. mentulatus was widespread in arid areas. h. contortus was present in a small number of sheep only, mainly in s ...	1982	7168719
gastrointestinal parasites and bacteria flora of wild animals in the borgu game reserve in nigeria.	faecal droppings from animals in the borgu game reserve were examined between the months of january and march 1981. these animals included buffalo, hartebeest, kob, roan antelope, genu cat, mangoose, warthog and monkey. haemonchus contortus was identified from the faeces of five buffalos, oesophagostomum species was identified from one warthog while strongyloides species was identified from two monkeys. no pathogenic bacteria was isolated in any of the faecal samples examined. the influence of w ...	1982	7174235
the seasonal incidence of helminth parasites and of oestrus ovis in karakul sheep in the kalahari region of south west africa, namibia.	the seasonal incidence of gastro-intestinal helminths and of oestrus ovis was determined by slaughter of successive groups of 4 tracer lambs, each exposed on pasture for 33 days. haemonchus contortus was present from march 1979 to early july 1979, with a generally increasing percentage of 4th stage larvae in each successive month. a "spring rise" in the egg count was seen in flock sheep in october 1978. oesophagostomum columbianum was recovered from tracers slaughtered in march 1979. apart from ...	1982	7177585
studies on haemonchus contortus. viii. attempts to protect suckling lambs against infestation with h. contortus.	a group of 12 merino lambs, 3,5 months of age, which were still suckling, were each dosed with 40 000 infective larvae of trichostrongylus axei on day 0. from day +62-day 64 each of these lambs and those of a 2nd group of 11 controls were dosed with 30 000 infective larvae of haemonchus contortus, and all the lambs of both groups were killed on day +90. attempts to use t. axei to protect them against subsequent challenge with h. contortus were unsuccessful.	1982	7177593
[effects of alternate grazing on faecal egg output of gastrointestinal nematodes and on the growth of calves and lambs].	during the period from 1975 to 1977, the faecal egg output of gastrointestinal nematodes and the gain in weight of a group of calves and a group of ewes with lambs on pastures alternately grazed by the two groups, were compared with the egg output and the gain in weight of a group of calves and a group of ewes with lambs not grazed alternately. the annual level of the egg output was identical in each comparable group. variations in larval differentiation were observed between the groups grazed a ...	1982	7179232
haemonchus contortus: the in vitro effects of anthelmintics on total glucose and glycogen contents, and total volatile fatty acids.		1982	7187820
an investigation of variables in a fecal flotation technique.	several variables in a standard vial fecal gravitational flotation technique were investigated. these were the specific gravity of the sodium nitrate flotation solution, duration of flotation and mesh sizes of strainers. the number of eggs which floated and adhered to a coverslip were counted and estimates of the number of eggs remaining in the strained fecal suspension and in the feces trapped on the strainer were made. eggs from hookworms, trichuris vulpis and toxocara canis in feces from dogs ...	1980	7190861
comparison of changes in resistance of haemonchus contortus eggs following withdrawal of thiabendazole selection.	two strains of haemonchus contortus with different levels of thiabendazole resistance were developed from the same parent strains by being subjected to different selection intensities. these two strains were each subdivided into two; one selected by thiabendazole in each generation, the other unselected for four generations. levels of thiabendazole resistance were monitored in each generation by an in vitro egg hatch technique. during this time the unselected strain with the higher level of resi ...	1982	7201152
self-curve and immunity following infection and reinfection in ovine haemonchosis.	egg expulsion and post mortem examination were used to compare self-cure and resistance to reinfection with haemonchus contortus in female merino sheep, aa and bb hemoglobin types. animals were infected by 500 or 5000 larvae of h. contortus once, or several times, before being challenged by 500 (low dose) or 500 (high dose) larvae. in aa sheep infected once by 500 larvae self-cure was detected by a challenge of either 500 or 5000 larvae while in multi-infected sheep only a challenge of 5000 l, i ...	1981	7201184
quantitative studies of ovine haemonchosis. 2. relationship between total worm counts of haemonchus contortus, haemoglobin values and bodyweight.	the relationships between haemonchus contortus burdens, haemoglobin levels and bodyweight, were examined in 50 commercial merino sheep, 9-18 months of age, in south-east queensland where haemonchosis was endemic. worm counts and haemoglobin levels were predictable (p less than 0.001, r = 0.68) from the equations log worm count = b.wt. x 0.06942 + log worm count x (-2.18896) + 12.51557. bodyweight was not predictable from either worm counts or haemoglobin levels. although bodyweight was represent ...	1982	7201195
quantitative studies of ovine haemonchosis. 3. the interpretation and diagnostic significance of the changes in serial egg counts of haemonchus contortus in a sheep flock.	an examination of the level and distribution of egg counts of h. contortus within an extensively managed flock of merino sheep in south-east queensland was carried out on three occasions over a ten week period. during this time the geometric mean egg count increased from 527 to 1331 eggs per gram, and although 26.3% of the flock were responsible for this increase, clinical evidence of haemonchosis was not observed. examination of the distribution of counts supported the hypothesis that counts fo ...	1982	7201196
relationship among particle size distribution, dissolution profile, plasma values, and anthelmintic efficacy of oxfendazole.	three mean particle sizes of oxfendazole raw material (1.65 micron, lot a; 3.2 micron, 10t b; 12.0 micron, lot c) were prepared and identically formulated as corresponding (a, b, and c) suspensions at 2.26% (w/v) concentration. studies involving microscopic examination, scanning electron microscope analysis, particle size distribution, and surface area measurement were carried out on raw materials. in vitro dissolution profiles were obtained for the suspensions. a comparative bioavailability stu ...	1980	7212443
the development, composition and maintenance of experimental populations of haemonchus contortus in sheep.	clun forest sheep, aged between 3 and 18 months and worm-free from birth, were given a single dose of 25 000 infective larvae of the nematode haemonchus contortus. the host animals were killed between 4 and 100 days after infection and the nematode populations were examined to determine size and composition. the relation between worm body length, dry weight and age was studied and growth curves were constructed. variations in the sex ratio for infections of different ages were noted. no evidence ...	1981	7220086
thiabendazole-resistant strains of haemonchus and ostertagia in california lambs.	ten parasite-free experimental lambs were inoculated intraruminally with a mixed-larvae inoculum which contained approximately 5,000 haemonchus contortus infective larvae. five lambs were treated with thiabendazole (66 mg/kg of body weight) and 5 were untreated controls. all lambs were killed 35 days after inoculations were done, and parasites present were recovered. reduction in numbers of recovered haemonchus contortus (25.7%) and ostertagia spp (26.8%) were not significant (p greater than 0.0 ...	1980	7224297
spermatogenesis in haemonchus contortus (nematoda: trichostrongylidae).	basic structure and development of spermatogonia, spermatocytes (primary and secondary), spermatids and spermatozoa have been studied in h. contortus (rud., 1803) with the aid of light microscopy.	1981	7227872
the impact of refugia on the development of thiabendazole resistance in haemonchus contortus.		1981	7228476
inorganic elements in the adults of haemonchus contortus (nematoda: trichostrongylidae).		1980	7229318
effect of oesophageal groove closure on the pharmacokinetic behaviour and efficacy of oxfendazole in sheep.	direct intraabomasal oxfendazole (ofz) administration resulted in the peak plasma ofz concentration occurring sooner and the area under the plasma ofz concentration curve being reduced when compared with intraruminal administration. glucose given directly into the abomasum of fistulated sheep caused a substantially greater elevation of plasma glucose levels than did direct administration into the rumen. this difference was subsequently used to indicate rumen bypass, by oesophageal groove closure ...	1981	7244379
experiments on inhibited development of haemonchus contortus and ostertagia circumcincta in sheep in the netherlands.	inhibited development of haemonchus contortus and ostertagia spp was studied in sheep. exposure of infective haemonchus contortus larvae for five weeks to 15 degrees c or 16 degrees c very effectively induced inhibited development but exposure to lower temperatures was much less effective. infection with fresh larvae cultured for seven or 12 days at 25 degrees c in the dark resulted only in very low rates of inhibited development. this was not much influenced by the age of the host or the month ...	1981	7244384
experimental cross-infections with gastrointestinal nematodes of sheep and cattle.	five parasite-free lambs and five parasite-free calves were infected experimentally with 20,000 third stage gastrointestinal nematode larvae cultured from faeces of sheep from five different farms. in the same way five lambs and five calves were infected with larvae cultured from faeces of calves from five different farms. host specificity of the nematodes was determined using the following parameters: infection rate; number, size, and stage of the worms; their distribution within the gastrointe ...	1981	7245840
resistance of haemonchus contortus to thiophanate.	the occurrence of a field strain of haemonchus contortus which was resistant to thiophanate and susceptible to thiabendazole and levamisole is reported. the ld95 of thiophanate for the strain was found to be 156.1 mg/kg and its resistance factor was 6.7. in possessing specific thiophanate resistance it differed from previously reported thiophanate resistant strains of h contortus which have been benzimidazole resistant worms that have possessed cross resistance to thiophanate.	1980	7255897
five generations of selection with benzimidazole and non-benzimidazole anthelmintics against benzimidazole resistant strains of haemonchus and ostertagia spp in sheep.	benzimidazole resistant strains of haemonchus contortus and ostertagia spp were subjected to selection pressure over five laboratory generations with the recommended dose rates of either cambendazole, oxfendazole or morantel. a change in response, with larger residual worm burdens remaining after treatment at the fifth generation, was shown for both cambendazole and oxfendazole against both species of nematode. no change in response against either species are shown for morantel. the results are ...	1981	7255903