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1.
Results of real-time PCR analysis of coproculture third stage larvae (L3) using genus specific TaqMan minor groove binder probes were compared with the results of morphological differentiation of L3 after coprocultured and direct morphological worm differentiation from gastrointestinal samples of eight sheep with naturally acquired nematodes infections. Faecal egg counts prior to postmortem confirmed infections with trichostrongyles with a geometric mean count of 4828 eggs per gram for all sheep. Individual egg counts correlated positively with total worm counts (correlation coefficient 0.794). Five different nematode species and one genus were found in the abomasi and small intestines: Cooperia curticei, Haemonchus contortus, Nematodirus spp., Teladorsagia (Ostertagia) circumcincta, Trichostrongylus axei and Trichostrongylus colubriformis. Coproculture of faecal eggs yielded five of these, Cooperia spp., Haemonchus spp., Ostertagia/Teladorsagia spp. and Trichostrongylus spp. Comparison between morphological L3 and worm differentiation data showed high congruence (94%). The agreement between PCR analysis of L3 after coproculture and direct morphological worm differentiation was 84%. Thus, real-time PCR was found to be suitable as a speedy and reliable diagnostic tool for the assessment of gastrointestinal nematode infections of ruminants in the field.  相似文献   

2.
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 possible future options for controlling anthelmintic resistant sheep trichostrongylids is briefly discussed.  相似文献   

3.
Clinical parasitism associated with multigeneric resistance to benzimidazole anthelmintics was investigated in four sheep flocks during February and March 1989. The genera considered resistant were Haemonchus and Nematodirus spp. on all four farms and Trichostrongylus and Ostertagia spp. on three of the four farms. It is suggested that when investigating cases of suspected drench resistance, post-drenching worm counts are useful to help identify the resistant worm species present.  相似文献   

4.
Larval cultures were used to determine the identities and occurrences of those parasites (excluding Nematodirus) represented by strongylid eggs at the time of anthehnintic administration in ovine faecal egg count reduction tests submitted to the Batchelar Animal Health Laboratory between 1992 and 1994. The numbers of individual nematode genera recorded in pre-treatment samples from these cases ranged from one to five and included infections of Haemonchus, Ostertagia, Ttichostrongylus, Cooperia and Oesophagostomum/Chabertia. Adequate egg representation for testing purposes by all five genera simultaneously was found to occur in only 17 (10%) of the 163 cases examined, with the majority (71%) of them containing between one and three nematode genera. The greatest representation occurred in those tests conducted during the months of February to May. However, even during this period, worm eggs of all five genera were concurrently present on only 16% of occasions. The importance of knowing what nematode genera are adequately represented at the time of routine faecal egg count reduction testing and the relevance of this information to reducing the likelihood of being misled when under- taking assessments of farm resistance status are discussed.  相似文献   

5.
The number and species of helminth parasites from three gemsbok (Oryx gazella) were recorded, and their faecal nematode egg counts and the level of pasture contamination determined. Six nematode genera were recovered and four species identified, of which Trichostrongylus rugatus was the most prevalent. Other nematode species recovered were Cooperia sp., Agriostomum sp., Haemonchus contortus, Nematodirus spathiger and Ostertagia ostertagi. None of the worms were present in all animals studied, and no new host associations were found. Cysticerci were recovered from the mesenteries of one gemsbok and a further two unidentifiable helminths were recovered from the abomasum and the kidney fat layer of another antelope.  相似文献   

6.
Larval cultures and faecal egg count reductions were used to determine the identities and frequencies of occurrence of nematode genera involved in cases of ovine anthelmintic resistance submitted to the Batchelar Animal Health Laboratory between 1992 and 1994. Based on an examination of 102 cases, it was found that, while there were some differences relating to the method of assessment, the genera most frequently involved were Trichostrongylus, Ostertagia and Nematodirus. Also implicated, although less commonly, were infections of Oesophagostomum/Chabertia, Haemonchus and Cooperia. The majority of cases involved resistance in two or more genera, with resistance in a single nematode genus occurring in 45% of cases. Most such monogeneric resistances comprised infections of Trichostrongylus (52%), Ostertagia (17%) or Nematodirus (11%). Anthelmintic resistance involving Haemonchus alone was found in only three cases. These results suggest that the potential role of narrow-spectrum drenches in the management and control of anthelmintic-resistant worms in New Zealand sheep is likely to be strictly limited.  相似文献   

7.
A controlled blind test was performed in 1984 to evaluate the anthelmintic activity of experimental formulations of compound F28249-alpha against gastrointestinal parasites in lambs in Kentucky. Twenty-five lambs were allotted to 5 groups of 5 lambs/group. The drug was administered SC to 2 groups (A, 0.2 mg/kg of body weight; B, 0.3 mg/kg) and orally to 2 groups (C, 0.2 mg/kg; D, 0.3 mg/kg). Group E received a placebo subcutaneously. Lambs were euthanatized 7 days after treatment for necropsy and identification and enumeration of worm parasites in the gastrointestinal tract. Group-E lambs harbored 7 genera (including 10 species) of nematodes and 1 genus of tapeworms. Worm collection data for group-A lambs indicated 97% to 100% of the mature Haemonchus, Ostertagia, Trichostrongylus, and Trichuris, and immature Haemonchus were removed; and 23% to 73% of the mature Cooperia, Nematodirus, and Strongyloides, and immature Nematodirus were removed. In group-B lambs, 94% to 100% of the mature Haemonchus, Nematodirus, Ostertagia, Trichostrongylus, and Trichuris, and immature Haemonchus were removed as were 70% to 84% of mature Strongyloides and immature Nematodirus, respectively, and 0% for mature Cooperia. The percentage of all nematodes removed in group C and D was 100%, except for Cooperia (95%) in group C and immature Nematodirus (93% and 95%), respectively. Toxicosis was not apparent. Small fibrotic or blood streaked lesions were observed at necropsy in muscle at the injection site of 2 lambs in group B and 1 lamb in group E.  相似文献   

8.
Critical anthelmintic tests and controlled trials were used to assess the efficiency of laevo -tetramisole hydrochloride against nematode infections in sheep and cattle.
In sheep, oral dose rates of 5 mg/kg and above were 94 to 100% effective against adult Haemonchus contortus , intestinal Trichostrongylus spp, Nematodirus spp, Oesophagostomum columbianum, O. venulosum and Chabertia ovina . A dose rate of 7.5 mg/kg was required for consistently high activity against Ostertagia spp, but activity against Trichostrongylus axei remained variable at this dose level. Efficiency against Trichuris ovis ranged from 76 to 100% at a dose rate of 10 mg/kg. The drug was 94 to 100% effective against 7-day old and 14-day old H. contortus , intestinal Trichostrongylus spp and O. colun bianum infections, and 83 to 89% effective against 14-day old Ostertagia spp and T. axei , at a dose rate of 5 mg/kg. Seven-day old Ostertagia spp larvae were highly resistant at a dose rate of 10 mg/kg, while activity against T. axei infections of the same age appeared variable at 5 and 10 mg/kg.
In cattle, subcutaneous treatment at dose rates of 1.5 mg/kg and above, and oral treatment at 7.5 mg/kg, were 93 to 100% effective against adult Haemonchus placei , intestinal Trichostrongylus spp, Nematodirus helvetianus, Cooperia spp and Oesophagostomum radiatum , and 84 to 98% effective against Ostertagia ostertagi . Against Trichostrongylus axei , a rate of 5 mg/kg subcutaneously was 83% effective, and a rate of 7.5 mg/kg orally 97% effective, while these dose rates gave 88 to 100% clearance of adult Dictyocaulus viviparous .  相似文献   

9.
Lambs severely parasitized by Haemonchus, Ostertagia, Trichostrongylus, Cooperia, Oesophagostomum, and Nematodirus were treated with fenbendazole (methyl 5-(phenylthio)-2-benzimidazolecarbamate) given at 3 dose levels: 3.5, 5.0, and 7.5 mg/kg of body weight. Efficacies against these genera, except Haemonchus and Nematodirus, were 100% at the 3 dose levels. Efficacies for the 3 doses against Haemonchus were 93.4, 95.3, and 99.8%, respectively, and against Nematodirus, 99.5, 99.6, and 100%. Efficacies for the doses against Trichuris were 69.1, 83.6, and 98.2%. Toxicosis due to the durg was not seen in these lambs, although they were severely debilitated.  相似文献   

10.
Fifteen (36%) of 42 mixed gastro-intestinal nematode infections in sheep, identified as drench-susceptible by the undifferentiated faecal egg count reduction test, were found to harbour anthelmintic-resistant worms when analysed on the basis of changes in the egg counts of individual nematode genera. Most of these cases involved resistance in a single nematode genus, with Ostertagia and Trichostrongylus being implicated most frequently. The possible contributory role of larval culture results in helping to reduce the chances of the faecal egg count reduction test producing these and similar types of errors is discussed.  相似文献   

11.
Infective larvae of selected batched of the following nematode species from sheep and cattle were examined for survival and infectivity (by injection into either the abomasum, the duodenum, or the jugular vein) after having been stored in liquid nitrogen for 103-136 months: Haemonchus contortus, Haemonchus placei, Ostertagia circumcincta, Ostertagia ostertagi, Marshallagia marshalli, Cooperia spp., Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus falculatus, Nematodirus spathiger, Nematodirus helvetianus, Oesophagostomum columbianum, Oesophagostomum radiatum, Chabertia ovina and Dictyocaulus filaria. Excluding D. filaria, a mean of 97.7% of the ovine and 96.0% of the bovine nematode larvae were alive when thawed. Compared with previous investigations in this series, little or no reduction occurred with time in either the survival or the viability of the nematodes from cattle, or in the survival of those from sheep. In contrast, the larvae developed poorly in sheep, possibly owing to parenteral treatment of the animals with ivermectin at a dosage of 0.4 mg kg-1, either 6 or 8 days before they were infected.  相似文献   

12.
Over a period of 1 year, from November 1997 to October 1998, the abomasa, blood and faecal samples of 121 dairy cows in Belgium were collected and examined for nematode infections. Nematodes were present in the abomasa of 110 animals. Ostertagia was found in all 110, Trichostrongylus was seen in 65 and Haemonchus in 14 abomasa. Overall, 91% of all trichostrongyles recovered were Ostertagia. The geometric mean total number of Ostertagia was 2750, with an average of 74% inhibited early fourth stage larvae (EL4). Between November and February >90% of the Ostertagia worm burden were EL4 stages. The majority of the animals (56%) harboured a low Ostertagia burden (100-5000) and 15% had a high burden (>10,000). Sixty-four percent of the coprocultures were positive and the genera recovered were Ostertagia sp. (100%), Trichostrongylus sp. (42%), Oesophagostomum (32%), Haemonchus sp. (29%) and Cooperia sp. (16%). A seasonal pattern was evident for serum Ostertagia-specific antibodies and for serum pepsinogen concentration, with the highest levels during the summer, and low values during the winter. Dictyocaulus viviparus specific antibodies were detected in the serum of eight (7%) animals.  相似文献   

13.
Type II ostertagiosis was found at necropsy in 9 American bison (Bison bison) from 3 farms in New York. Clinical signs included severe diarrhea, emaciation, unthrifty coats, anemia, and weakness. In severely affected animals, the macroscopic abomasal changes consisted of irregular thickening and edema of the mucosa, resulting in a pebbly or morocco-leather appearance. Microscopically, many gastric pits and glands were dilated, lined by hyperplastic epithelium, and contained nematode sections or debris. Parasites recovered included Ostertagia ostertagi, Trichostrongylus axei, Trichostrongylus lerouxi, Cooperia oncophora, Haemonchus contortus, Nematodirus helvetianus, Trichuris discolor, Setaria labiato-papillosa, Dictyocaulus viviparus, Hypoderma lineatum, and Sarcocystis sp. Nodules in the small and large intestine were attributed to Oesophagostomum sp. Trichostrongylus lerouxi, Trichuris discolor, and Nematodirus helvetianus are reported from bison for the first time.  相似文献   

14.
A study was made to compare the numbers of infective ovine nematode parasite larvae on an open pastured block and an adjacent block forested with Pinus radiata at 200 stems per hectare. Each block consisted of two paddocks which had similar nematode parasite egg contamination. Infective larvae of six genera were recovered over a 12 month period viz., Trichostrongylus spp., Ostertagia spp., Cooperia spp., Nematodirus spp., Chabertia/Oesophagostomum spp. and Haemonchus sp. A significantly higher recovery of Trichostrongylus spp. (p<0.01) and Ostertagia spp. (p<0.05) from the pine forested block was probably due to the more favourable climatic environment under the pines. The lower mean body weights of sheep grazing the pine block was considered to be due to the greater exposure to infective larvae and marginal under-nutrition.  相似文献   

15.
A study was initiated to (1) determine species of gastrointestinal nematodes present in cattle in selected areas of Oregon, (2) examine seasonal abundance of these nematodes as an indicator of periods of transmission, and (3) determine when developmental inhibition occurs in the major genera of nematodes encountered. Four study sites were chosen: Corvallis, Langlois, near Fort Rock, and southeast of Klamath Falls on the Oregon-California border. Eight sets of three to four tracer calves each were introduced onto pasture at each site over a 2 year period with time of turn out onto pasture corresponding to late spring, mid-summer, late fall and late winter. At Corvallis, a distinct seasonality in parasite transmission was evident, peaking during the fall and winter. At Langlois, transmission was fairly constant throughout the year. No discernible patterns were evident at either Klamath Falls or Fort Rock. Eight nematode genera were found during the study. Ostertagia, Cooperia, Nematodirus and Trichostrongylus were present at all study sites and were the most common genera at each. Trichuris was found at all sites except Klamath Falls. Oesophagostomum was present in tracers only from Langlois and Corvallis while Haemonchus was found only at Klamath Falls and Fort Rock. Capillaria was only present at Klamath Falls. Where possible, specific transmission patterns for Nematodirus, Cooperia, and Ostertagia were determined for each site. Nematodirus was transmitted fairly steadily at both Langlois and Corvallis but was quite variable at Fort Rock. Developmental arrest was detected in this genus at all study sites during the fall and/or winter. Cooperia exhibited the most seasonally defined pattern of transmission, peaking during the fall and winter at Langlois, Corvallis and Klamath Falls. Hypobiotic larvae of Cooperia were present during the fall and/or winter only at Langlois and Corvallis. Peak transmission of Ostertagia at Langlois and Corvallis occurred during the fall and winter. At Fort Rock, transmission was lowest in the fall and increased in the winter. Hypobiotic larvae were evident in the fall and winter at Corvallis, Fort Rock and Klamath Falls. These data suggest Type II ostertagiasis may occur in late winter through spring in these areas. Hypobiotic larvae of Ostertagia were not detected at Langlois. The lack of appropriate environmental stimuli is one possible explanation for the apparent lack of hypobiosis at that site.  相似文献   

16.
Calves experimentally infected with Haemonchus, Ostertagia, and Cooperia, and to lesser degrees with Trichostrongylus, Oesophagostomum, Nematodirus, and Bunostomum were used in a controlled experiment to record the anthelmintic efficacy of a benzimidazole compound methyl 5-(phenylthio)-2-benzimidazolecarbamate at dosage levels of 3.5, 5, and 7.5 mg/kg bodyweight. With the 3 dosages, reductions of Haemonchus were 96.7, 99.2, and 99.8%; of Ostertagia, 97.2, 97.2, and 99.5%; and of Cooperia, 99.9, 99.9, and 99.9%. Pronounced reductions were also recorded for Trichostrongylus, Nematodirus, Oesophagostomum, Trichuris, and Capillaria, but these populations were too numerically small or too unevenly distributed within the control groups to be given much emphasis. The experimental parasitic populations which developed in the 10 control calves amounted to 91, 763 worms (total).  相似文献   

17.
The efficacy of moxidectin, a new endectocide against natural nematode infections, was evaluated. Twenty-five calves were divided into two groups of eight calves each and a third group of nine calves. Moxidectin was administered s.c. to two groups (I, 0.2 mg kg-1 body weight (BW); II, 0.3 mg kg-1 BW) and the third group (III) received the vehicle (placebo) s.c. Two pre-treatment and one post-treatment faecal nematode egg count determinations were made from all calves, and they were necropsied 2 weeks after treatment for the identification and enumeration of nematode parasites. Group III calves, which received the drug-free vehicle, harboured eight species of nematodes (Ostertagia ostertagi, Trichostrongylus axei, Cooperia oncophora, Cooperia punctata, Nematodirus helvetianus, Trichuris discolor, Oesophagostomum radiatum and Dictyocaulus viviparus). The mean total worm burden for this group was 8935. There was a significant reduction in the numbers of many species of nematodes (Ostertagia, Trichostrongylus, Cooperia and Nematodirus) in both treated groups. Cooperia oncophora was reduced by 94% in Group I and by 96% in Group II, while all other nematode species were reduced by 99%. Immature stages of Ostertagia and Nematodirus were significantly reduced in the two treated groups. Two weeks after treatment, the mean faecal egg counts of both treated groups were reduced by more than 98%. There was no significant difference in mean total worm burdens or egg counts between the two treated groups.  相似文献   

18.
The efficacy of an oral formulation of the newly developed parasiticide, moxidectin, was tested against benzimidazole-resistant Haemonchus contortus, Trichostrongylus colubriformis, and Nematodirus spathiger, levamisole-resistant Ostertagia circumcincta, and susceptible Cooperia curticei infections in weaned lambs. Thirty-two lambs were experimentally infected with mixed doses of the above strains of nematodes. They were allocated into four treatment groups by stratified randomisation using liveweights and faecal egg counts 28 days later. One group received moxidectin at 0.2 mg/kg liveweight, one group oxfendazole at 4.5 mg/kg liveweight, one group levamisole at 7.5 mg/kg liveweight and the last group remained untreated as the control. Worm burdens in the lambs at slaughter 10 days after oral treatment confirmed the resistance status of the nematode strains used, and showed that moxidectin had a greater than 99.9% efficacy (p<0.01) against all of them. No adverse effects due to treatment with moxidectin were observed in any of the animals.  相似文献   

19.
Ten 4-month-old female sheep of the Karagouniko dairy breed were used to monitor the seasonal fluctuations of strongyle infections in sheep during the first year of grazing under the traditional production system in the region of Trikala, Greece, where control of nematodes is currently based exclusively on the frequent use of anthelmintics which might contribute to the appearance of anthelmintic resistance. The sheep grazed communal pasture plots and did not receive any anthelmintic treatment during the entire study period. Faecal egg counts (epg), plasma pepsinogen levels, blood values, and genera of parasitic strongyles recovered from coprocultures were recorded monthly. Mean epg for strongyle-type eggs were significantly higher during summer. Mean plasma pepsinogen levels were significantly higher during spring and summer. The genera of parasitic strongyles recovered from the faecal cultures were Haemonchus, Ostertagia, Trichostrongylus, Cooperia, Nematodirus, Oesophagostomum, and Chabertia. The percentages of larvae for Haemonchus, Ostertagia, Cooperia, and Oesophagostomum were significantly higher during winter. The percentages of larvae for Trichostrongylus were significantly higher during summer. During summer, levels of RBC, HGB, and HCT were depressed and levels of MCV, MCH, and MCHC were elevated. Mean epg for strongyle-type eggs had a significant inverse correlation with RBC, HGB, HCT, and positive correlation with MCH, MCHC, and percentages of eosinophils in differential leucocyte counts. The seasonal pattern of infection observed in the present study indicates that it is possible to decrease the number of treatments to one per year, thus, reducing the possibility for the appearance of anthelmintic resistance.  相似文献   

20.
The activity of thiabendazole at 100 mg/kg was tested against the arrested larvae of Ostertagia spp, Haemonchus contortus, Trichostrongylus axei, Nematodirus spp and Chabertia ovina in natural infections, in 10-month-old lambs. The result, assessed by means of worm counts, showed the treatment to be very effective.  相似文献   

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