Efficacy of a fenbendazole-triclabendazole combination against Fasciola hepatica and gastrointestinal nematodes in sheep

A fenbendazole and triclabendazole combination was tested against experimentally induced 6-and 14-week-old infections of Fasciola hepatica and naturally acquired infections of gastrointestinal nematodes in sheep. Forty-eight sheep were divided randomly into six treatment groups of eight animals each. At 7.5 and 10.0 mg kg-1 body weight (BW) (3.75 and 5.0 mg kg-1 BW of each drug), the drug combination was 98.3 and 99.7% effective against 6-week-old F. hepatica infections, and 100 and 99.9% effective against 14-week-old infections. At the same drug dosages, the drug combination was effective against naturally acquired adult Ostertagia spp. (97.3-100%) and adult Nematodirus spp. (90.3-99.9%). No adverse effects associated with treatment were noted.     

Efficacy of a moxidectin/triclabendazole oral formulation against mixed infections of Fasciola hepatica and gastrointestinal nematodes in sheep

We have evaluated the efficacy in sheep of a combination drench formulation at the recommended dose rate of 0.2 mg moxidectin/kg bodyweight and 10 mg triclabendazole/kg bodyweight against an experimental infection with Fasciola hepatica and a natural infection with gastrointestinal nematodes. We confirmed that the efficacy of reducing fecal egg output was 98.3% for trichostrongyle eggs and 100% for F. hepatica eggs. Based on adult worm and fluke recovery, the efficacy varied according to the target species. A reduction was found in the number of Teladorsagia circumcincta, Trichostrongylus spp., Nematodirus spp., and Trichuris spp. greater than 95%, but the efficacy for Oesophagostomum spp. varied, with values below 90%. The reduction in F. hepatica was higher than 95% for all stages. The effectiveness of the formulation was also confirmed by an increase in total proteins and albumin following treatment.     

Efficacy of concomitant early summer treatment with fenbendazole and clorsulon against Fasciola hepatica and gastrointestinal nematodes in calves in Louisiana

The efficacy, safety, and compatibility of fenbendazole (FBZ) and clorsulon (CLN) were tested after oral administration of label recommended and of higher (5x) dosage rates to calves naturally infected with gastrointestinal nematodes and Fasciola hepatica. Results for 42 calves allotted to 4 treatment groups indicated a similar efficacy against mature F hepatica by FBZ (5 mg/kg of body weight) and CLN (7 mg/kg) in a combined oral suspension, compared with CLN (7 mg/kg) alone (100 vs 99% reduction). A lesser efficacy was observed against immature flukes (88.6 and 84.9% reduction, respectively). Calves given 25 mg of FBZ/kg and 35 mg of CLN/kg had nearly complete reduction of both mature (99.6%) and immature flukes (99.1%). Fasciola egg counts were reduced by greater than 99.5% in all treated groups. Against Ostertagia ostertagi, the percentage of efficacy of the combined FBZ (5 mg/kg) and CLN (7 mg/kg) treatment was 94.3% against adults and 81.3% against inhibited larvae. Efficacy against all other nematodes was 100%, except against Cooperia spp adults (98.3%) and immature Oesaphagostomum radiatum (88.0%). At 5 x dosage rates for FBZ and CLN, percentage of removal of adults and inhibited larvae of O ostertagi was 99.3 and 99.0%, respectively, and 99 to 100% for other nematodes. Results indicate that FBZ and CLN are compatible when mixed together and administered as an oral suspension to cattle and that the efficacy is similar to that of the drugs individually. On the basis of further results, we suggest that summer treatment may be superior in preventive value for gastrointestinal nematodes and F hepatica, compared with spring treatment, because of seasonal infection dynamics of the major cattle parasites in Louisiana.     

Efficacy of moxidectin against gastrointestinal nematodes of cattle.

Three groups of 11 naturally infected crossbred beef calves were injected subcutaneously with moxidectin 1 per cent injectable at 0.2 or 0.3 mg moxidectin/kg bodyweight or with the unmedicated vehicle. Nematode infections had been acquired during grazing from December to April. Based on the faecal egg counts and total worm counts of the control calves at necropsy (11 to 13 days after treatment) most of the calves had heavy parasitic burdens. Ostertagia ostertagi was predominant and the mean numbers of adults, developing fourth stage larvae (L4) and inhibited early L4 were 45,906, 10,061 and 68,918, respectively. Haemonchus placei and Trichostrongylus axei were also present in the abomasa. Three species of Cooperia, Oesophagostomum radiatum L4 and T colubriformis adults were found in the intestinal tract. Both dosages of moxidectin were equally effective (P < 0.05) against all the abomasal nematodes (99.9 to 100 per cent) and the intestinal tract nematodes (99.4 to 100 per cent). No adverse reactions to the moxidectin treatment were observed. Abomasal pathology characteristic of heavy O ostertagi infection was observed in the control calves, but not in the treated calves.     

Efficacy of thiophanate and albendazole against natural infections of Dicrocoelium dentriticum, Fasciola hepatica, and gastrointestinal nematodes and cestodes in sheep

The anthelmintic efficacy of thiophanate and albendazole was compared in sheep with heavy infestations of Dicrocoelium dentriticum. The effectiveness of each drug was determined by counting the numbers of D. dentriticum in animals killed 21 days after treatment. In one group, the dose of thiophanate recommended for use against gastrointestinal (GI) nematodes (50 mg kg-1 live weight) was found to be 74.4% effective against D. dentriticum. Two tablets (each containing 76 mg of active ingredient) of albendazole per 30 kg live weight were given to a second group and the dose repeated after 1 week. Under this regime, albendazole was found to be 12.7% effective against D. dentriticum. The effect of each drug on other parasites was as follows; thiophanate had no effect against Fasciola hepatica or cestodes, while albendazole was 71.5% effective against F. hepatica and 100% effective against cestodes. Both drugs were highly effective against GI nematodes.     

Efficacy of clorsulon against mature, naturally acquired Fasciola hepatica infections in cattle and sheep

Clorsulon (3.5 or 7 mg/kg of body weight) was given orally to mature cows (dairy or beef) and to mature mixed-breed sheep harboring patent infections of Fasciola hepatica. Eighteen animals of each species were assigned to a control group (drug vehicle) or to 1 of 2 treatment (3.5 or 7.0 mg/kg) groups of 6 animals each. On posttreatment days 8 (cows) or 14 (sheep), the animals were slaughtered for recovery of flukes. In cows, the efficacy (P values for treatment groups vs control) of clorsulon against infections of mature F hepatica was 99.21% (P less than or equal to 0.0065) at 3.5 mg/kg and was 100% (P less than or equal to 0.0039) at 7 mg/kg. In sheep, the efficacy was 93.33% (P less than or equal to 0.0104) at 3.5 mg/kg and was 100% (P less than or equal to 0.0039) at 7 mg/kg. These results indicate that clorsulon is a highly effective compound for the treatment of mature F hepatica in cows and sheep.     

Efficacy of febantel paste against naturally acquired gastrointestinal nematodes of cattle

Twenty calves with naturally acquired gastrointestinal nematode infections were assigned to 10 replicates of 2 calves each and were treated with febantel paste (5 mg/kg of body weight, PO) or an equivalent volume of paste vehicle (control calves). Adverse reactions were not observed after febantel treatment. At necropsy, gastrointestinal nematode counts in febantel-treated calves, compared with control calves, were reduced by over 99% for all major species except Trichuris discolor, counts of which were reduced by only 69%. Counts of gastrointestinal nematode eggs in feces of febantel-treated calves were reduced by 100% after treatment.     

Comparative efficacy of clorsulon and albendazole against Fasciola hepatica in cattle

In a dosage-confirmation trial, anthelmintic activities of clorsulon and albendazole against Fasciola hepatica were evaluated and compared. Twenty-eight cattle (8 to 12 months old) with natural F hepatica infections were randomly allotted to 4 groups of 7 cattle each: group 1, no treatment (controls); group 2, clorsulon suspension given orally at 3.5 mg/kg of body weight; group 3, clorsulon suspension given orally at 7 mg/kg; and group 4, albendazole paste given orally at 10 mg/kg. At necropsies, performed 7 and 8 days after treatment, control cattle harbored a geometric mean of 133.2 F hepatica, 16.0 of which were immature. Clorsulon administered at 3.5 mg/kg or 7 mg/kg resulted in greater than 99% removal of F hepatica, including immatures. Albendazole treatment resulted in a 76% overall reduction in F hepatica, including a 91% reduction of immatures. Fascioloides magna also were found in the cattle, but neither clorsulon nor albendazole caused significant reductions of the parasite. Adverse reactions to the 2 drugs were not observed.     

三氯苯咪唑混悬剂对牦牛肝片吸虫的驱虫试验

应用三氯苯咪唑混悬剂,选择自然感染肝片吸虫的牦牛60头进行了驱虫试验。结果表明:①三氯苯咪唑混悬剂5mg/kg体重剂量对肝片吸虫的虫卵转阴率、减少率分别为83.3%、90.0%,对成虫的驱净率和驱虫率分别为91.7%、93.8%,对童虫的驱净率和驱虫率分别为83.3%、90.1%;10、15mg/kg剂量对肝片吸虫虫卵转阴率、减少率及成虫、童虫的驱净率和驱虫率均达100%;②三氯苯咪唑混悬剂10mg/kg剂量与同剂量三氯苯咪唑片剂的驱虫效果无明显差异;③三氯苯咪唑混悬剂3个剂量组试验牛未见异常反应。试验证明三氯苯咪唑混悬剂10、15mg/kg剂量驱除牦牛肝片吸虫高效安全,临床使用以10mg/kg剂量为宜。     

Efficacy of ivermectin administered via sustained-release bolus against gastrointestinal nematodes in cattle

Twelve calves (mean weight, 175.5 kg) were used to confirm efficacy of ivermectin delivered from a prototype sustained-release bolus against naturally acquired gastrointestinal nematodes including early fourth-stage (inhibited) larvae of Ostertagia ostertagi. The calves were allocated by restricted randomization on weight to 1 of 2 groups: controls, to which a placebo bolus was given orally, and treated calves, to which a sustained-release bolus designed to deliver 8 mg of ivermectin/day at a steady rate was given orally. After treatment, the 2 groups were housed in separate pens with concrete flooring. Twenty-eight days after treatment, all calves were euthanatized and necropsied. The ivermectin-treated calves had no larval or adult Ostertagia spp and significantly (P less than 0.01) fewer adult Trichostrongylus axei and adult Cooperia (C oncophora, C punctata and C surnabada) than control calves. Efficacy of ivermectin was greater than 99% for Cooperia spp, and 100% for other parasites. Drug-related adverse reactions were not observed.     

国产三氯苯咪唑驱除山羊肝片形吸虫效果试验

以国产三氯苯咪唑对自然感染肝片形吸虫的山羊进行了驱虫试验，并以硝氯酚为药物对照。结果表明，三氯本咪唑5mg/kg体重的剂量对肝片形吸虫成虫和童虫的驱虫率分别为99.3%和92.9%，驱净率为75％；三氯苯咪唑10mg/kg体重的剂量对肝片形吸虫成虫和童虫的驱虫率均为100％，驱净率为100％；硝氯酚5mg/kg体重剂量对肝片形吸虫成虫驱虫率为100％，但对童虫的仅为74.3%，而驱净率仅为60％。在整个试验期间试验羊均无不良反应。     

Efficacy of orally administered moxidectin against naturally acquired gastrointestinal nematodes in cattle.

Anthelmintic efficacy of moxidectin, an experimental antiparasitic macrocyclic lactone, was evaluated in a group of 15 calves harboring naturally acquired gastrointestinal nematodes. Three groups of 5 calves each served as untreated controls (group 1) or principals that were given moxidectin PO at the rate of 0.2 mg/kg (group 2) or 0.4 mg/kg (group 3) of body weight. Equal numbers of control and treated calves were necropsied for parasite recovery on days 10 (3 control and 3 of each treatment group) and 11 (2 control and 2 of each treatment group) after treatment. Efficacies at both doses were greater than 99.8 and 99.9% against active and inhibited larvae and adults of Ostertagia spp, respectively. The overall mean efficacy of each dose was greater than 99.9%.     

Sero-diagnosis of Fasciola hepatica infections in cattle

An antigen was prepared from metabolic products which were produced by maintaining Fasciola hepatica adults in RPMI tissue culture medium for 24 h. The antigen compared favourably with a soluble extract of adult flukes when used in an enzyme-linked immunosorbent assay (ELISA). Experimentally infected calves were used to evaluate the sensitivity of the test and a survey from areas of both traditionally high and low incidence of the disease was carried out. Evidence is presented which suggests that this metabolic antigen could be used for the sero diagnosis of naturally occurring infections. In addition the use of a microcomputer to read, file and analyse the results enabled a very large number of samples to be processed daily.     

Resistance of Fasciola hepatica against triclabendazole in cattle in Patagonia (Argentina)

In the winter of 2008, cattle on a farm in the province of Neuquen, Argentina died from subacute and chronic liver fluke disease despite four previous treatments with Triclabendazole (TCBZ). In the spring of 2009, a preliminary efficacy test revealed good performance using nitroxynil, whereas TCBZ efficacy was only 18% by egg counts of Fasciola eggs in the faeces. Resistance to Fasciola hepatica to TCBZ has never been reported in South America, so in January of 2010 a controlled trial was conducted to confirm and to define the degree of resistance in this herd. In a clinical trial, the fluke egg output was monitored on Days 14 and 21 and serum enzymes gamma-glutamyl transpeptidase (GGT) and glutamic-oxaloacetic transaminase (GOT) on Days 0 and 21 in 36 calves treated with TCBZ or with closantel. The results showed a reduction of 100% in fluke egg output at Days 14 and 21 for closantel. The mean epg in the TCBZ-treated groups did not decrease. Because of the fact that in this study TCBZ treatment in cattle had no effect, even at double the recommended dose, it is highly indicative that resistance of F. hepatica against TCBZ is present on this farm. The GGT and GOT levels decreased in the closantel-treated group as a result of the treatment at 21 days after dosing. To evaluate the importance of TCBZ resistance in F. hepatica in Argentina, a study on more farms from endemic areas is needed.