moxidectin and closantel

Topics: Animals; Anthelmintics; Anti-Bacterial Agents; Cattle; Cattle Diseases; Drug Combinations; Female; Ivermectin; Macrolides; Male; Paramphistomatidae; Salicylanilides; Sulfanilamides; Trematode Infections

In a survey involving 34 sheep flocks spread over the Netherlands anthelmintic resistance (AR), based on a fecal egg count reduction (FECR) test, was determined for six different products. The study was conducted in ewes shortly after lambing during spring 2015. A FECR of less than 90%, indicating presence of AR against one or more nematode genera producing strongylid eggs, was found in 22 of 30 (73.3%) flocks against oxfendazole, 18 of 23 (78.3%) flocks against ivermectin, 15 of 32 (46.9%) flocks against moxidectin, and 2 of 26 (7.7%) flocks against monepantel. No AR was observed against levamisole. If oxfendazole resistance was observed, Haemonchus contortus was involved in 90.5% of the cases. If resistance against ivermectin, moxidectin or monepantel was observed, it invariably involved H. contortus. In the majority of cases resistance was also observed for Teladorsagia circumcincta and/or Trichostrongylus spp, between which no distinction was made in this study. Based on FECR 9 of 15 (60.0%) flocks showed resistance against closantel, which was mainly due to closantel not being effective against most other nematode species than H. contortus. However, in 44.4% of flocks showing reduced FECR it did involve H. contortus as well. Multi-drug resistance (excluding closantel) was found in 16 flocks, of which 8 showed resistance against 2 products, 7 against 3 products and 1 flock showed resistance against 4 products. If resistance against 3 or 4 products was present, there invariably was resistance against both ivermectin and moxidectin. Overall, of the 22 flocks in which both macrocyclic lactones (ML) were tested, 4 (18.2%) showed no resistance against both products, 9 (40.9%) showed resistance against ivermectin only, and 9 (40.9%) showed resistance against both MLs. It is concluded that AR is widespread in sheep in the Netherlands and involves products from all major anthelmintic classes, with possibly the exception of levamisole. It appears that the macrocyclic lactones have lost much of their efficacy against sheep nematodes over the last decade.

Topics: Aminoacetonitrile; Animals; Anthelmintics; Benzimidazoles; Drug Resistance; Feces; Haemonchiasis; Haemonchus; Intestinal Diseases, Parasitic; Ivermectin; Levamisole; Macrolides; Parasite Egg Count; Salicylanilides; Sheep; Sheep Diseases

Gastrointestinal nematodes resistant to anthelmintics have been reported in several regions of Brazil, and they may be associated with economic losses for the cattle industry. This study aimed to evaluate the resistance status of gastrointestinal nematodes from naturally infected beef cattle to several commercially available anthelmintics, as well as to test the efficacy of combinations of anthelmintics against multi-resistant gastrointestinal nematodes. Ten farms located in Rio Grande do Sul state were selected by: farmers' consent; extensive raising system; availability of calves aged from 7 to 9 months naturally infected by gastrointestinal nematodes; absence of anthelmintic treatment for 60 days before the study; and presence of 70-100 calves or more of both genders with ≥ 200 eggs per gram of feces (EPG) (sensitivity of 50 EPG). These calves were distributed into 10 groups (of 7-10 animals) per farm and treated with ivermectin, doramectin, eprinomectin, fenbendazole, closantel, nitroxynil, disophenol, levamisole, albendazole, or moxidectin. Feces were collected 2 days before treatment and 14 days after treatment. Additional groups of 7-10 calves were used to test six different two-drug combinations at four of the studied farms. In general terms, fenbendazole was the most effective drug, followed by levamisole, disophenol, and moxidectin. However, parasite resistance to multiple drugs was found in all herds, especially in the genera Cooperia spp., Trichostrongylus spp., and Haemonchus spp.. Some of the two-drug combinations were effective against nematode populations identified as resistant to the same compounds when used as single drugs. The most effective combinations were moxidectin + levamisole, doramectin + fenbendazole, and levamisole + closantel. In this study, parasites resistant to the main commercially available anthelmintics were found in all herds, and some combinations of two active components belonging to different chemical groups were effective against multi-drug resistant gastrointestinal nematodes.

Topics: Albendazole; Animals; Animals, Domestic; Antinematodal Agents; Brazil; Cattle; Cattle Diseases; Drug Resistance, Multiple; Drug Therapy, Combination; Feces; Fenbendazole; Haemonchus; Intestinal Diseases, Parasitic; Intestines; Ivermectin; Levamisole; Macrolides; Nematoda; Nematode Infections; Parasite Egg Count; Red Meat; Salicylanilides

Early in 2015, sheep in a summer rainfall area of NSW, Australia, displayed signs of haemonchosis despite treatment with monepantel. A faecal egg count reduction test (FECRT) was performed on yearlings with natural field infections using various anthelmintics. Only a four-way combination drench achieved a reduction in faecal egg count (FEC) greater than 95%. The combination contained abamectin, albendazole, levamisole and closantel. Treatments with a derquantel/abamectin combination, monepantel and moxidectin reduced FECs by 93, 31, and 30% respectively. Sheep treated with abamectin displayed an increase in FEC of 22%. Larval differentiation counts conducted 10days post-treatment showed that 100% of survivors were Haemonchus sp. This result confirms for the first time monepantel resistant Haemonchus in sheep in NSW, and is amongst the first of the Australian cases in sheep not associated with goats. A second FECRT was performed using sheep from the moxidectin and abamectin treatment groups in the first FECRT. In this second FECRT, monepantel treatment reduced FECs by 51% and 29% in the sheep previously treated with moxidectin and abamectin respectively. This suggests monepantel, in combination with moxidectin, may give some control against severely abamectin resistant Haemonchus.

Topics: Albendazole; Aminoacetonitrile; Animals; Anthelmintics; Australia; Drug Therapy, Combination; Feces; Haemonchiasis; Haemonchus; Indoles; Ivermectin; Macrolides; Male; Oxepins; Parasite Egg Count; Random Allocation; Salicylanilides; Sheep; Sheep Diseases; Treatment Failure

The strategic use of moxidectin or closantel in combination with levamisole (LEV) to control gastrointestinal nematodes of sheep in the highlands of central Kenya was examined. Thirty Corriedale female lambs aged between 6 and 8 months were assigned to three treatment groups of ten lambs each. The three groups of lambs were set stocked on separate paddocks for the entire study period of 12 months. Lambs in Group 1 were dewormed strategically with moxidectin at 0.2 mg/kg body weight and those in Group 2 with closantel at 10 mg/kg body weight together with LEV at 7.5 mg/kg body weight. These strategic treatments were given 3 weeks after the onset of both the short and long rains and at the end of the long rainy season. The third group of lambs remained untreated (control group). Nematode infections in the treated groups of lambs and larval infectivity for the pastures on which the lambs were grazing were well controlled compared with the untreated control group. This resulted in higher weight gains and packed cell volume (PCV) in the treated lambs compared with the untreated lambs. These parameters were comparable between the lambs treated with moxidectin and those treated with closantel plus LEV. The estimated monitory benefit per animal from the control of gastrointestinal nematodes using moxidectin or closantel in combination with LEV when compared with animals in the control group were US dollars 26 and 25, respectively. It was concluded that worm control strategies for sheep in the study area, which are based on anthelmintic treatments during the rainy seasons, are effective. Due to the extended period during which pastures remain infective in the high rainfall central highlands of Kenya, anthelmintics with sustained action such as moxidectin or closantel may be most effective. On farms where resistance to the commonly used benzimidazoles or LEV groups of anthelmintics has developed, moxidectin or closantel may be used in helminth control programs for sheep.

Topics: Animals; Anti-Bacterial Agents; Antinematodal Agents; Drug Therapy, Combination; Female; Gastrointestinal Diseases; Kenya; Levamisole; Macrolides; Nematode Infections; Salicylanilides; Seasons; Sheep

The faecal egg count reduction test (FECRT) was conducted on 39 sheep farms and 9 goat farms located in Peninsular Malaysia. The anthelmintic groups used in these tests were the benzimidazoles, levamisole, the benzimidazole/levamisole combination, macrocyclic lactones and closantel. Results indicated that the prevalence of resistance to the benzimidazole group was high, with approximately 50% of the sheep farms and 75% of the goat farms having resistant nematode parasite populations present. Resistance to levamisole, closantel and ivermectin was also detected. Differentiation of the infective larvae derived from faecal cultures indicated that by far the most predominant parasite species was Haemonchus contortus.

Topics: Animal Husbandry; Animals; Anthelmintics; Anti-Bacterial Agents; Benzimidazoles; Drug Resistance; Feces; Goat Diseases; Goats; Haemonchiasis; Haemonchus; Ivermectin; Levamisole; Macrolides; Malaysia; Parasite Egg Count; Prevalence; Salicylanilides; Sheep; Sheep Diseases

A culture medium in which 1st instar larvae of Oestrus ovis can survive for up to 2 months has been developed with Dulbecco's Modified Eagle's Medium (DMEM) pH 7.7, penicillin 100 U/ml, streptomycin 100 micrograms ml-1, gentamicin 10 micrograms ml-1 and foetal calf serum (50%) added. Larvae were incubated in flat plastic tissue culture bottles (3 ml of medium) in a 5% CO2 atmosphere at 37 degrees C in darkness. Subsequently an antiparasitic in vitro screening test was developed with moxidectin and closantel. These drugs were not as effective in vitro as in vivo. This might be due to the fact that they cause damage to parasites and host immune responses, then contribute to their death.

Topics: Animals; Anti-Bacterial Agents; Antiparasitic Agents; Diptera; Drug Evaluation, Preclinical; Insecticides; Larva; Macrolides; Salicylanilides

A strain of Haemonchus contortus (CAVR) isolated in Australia was found to be resistant to ivermectin (IVM) with 0.4 mg kg-1 of the anthelmintic failing to significantly reduce worm burdens. Resistance to IVM was sex-influenced in the CAVR strain with adult males showing a greater sensitivity to IVM. Cross resistance to moxidectin was evident with approximately 15% of the population surviving a dose of 0.1 mg kg-1. The free-living stages of the CAVR isolate had a reduced sensitivity to avermectin (AVM) inhibition of development and motility. Similar structure-activity patterns and resistance factors were obtained for a series of related AVMs as inhibitors of larval development and L3 motility in CAVR and White River II, an IVM-resistant H. contortus isolate from South Africa. Further, both isolates were found to be 3 times more sensitive to paraherquamide than a susceptible H. contortus isolate. This suggest that the same resistance mechanism is operating in both isolates. The CAVR strain is susceptible to the benzimidazoles, levamisole and closantel.

Topics: Animals; Anthelmintics; Anti-Bacterial Agents; Australia; Benzimidazoles; Drug Resistance; Drug Therapy, Combination; Female; Haemonchiasis; Haemonchus; Ivermectin; Levamisole; Macrolides; Male; Salicylanilides; Sheep; Sheep Diseases

The anthelmintic efficacy of benzimidazoles, levamisole, closantel, ivermectin and moxidectin was evaluated on an institutional farm in Malaysia using faecal egg count reduction tests, controlled slaughter trials and an in vitro egg hatch assay. The results of this study indicated simultaneous resistance of Haemonchus contortus against benzimidazoles and ivermectin and of Trichostrongylus colubriformis against benzimidazoles and levaminsole on the same farm. Moxidectin was effective against the ivermectin resistant H. contortus.

Topics: Animal Husbandry; Animals; Anthelmintics; Anti-Bacterial Agents; Benzimidazoles; Drug Resistance; Haemonchiasis; Haemonchus; Ivermectin; Levamisole; Macrolides; Malaysia; Parasite Egg Count; Salicylanilides; Sheep; Sheep Diseases; Trichostrongylosis; Trichostrongylus

The efficacy of moxidectin at 0.2 mg kg-1 live body mass against the multiple anthelmintic resistant White River Krtz strain of H. contortus was determined and compared to that of ivermectin, a benzimidazole, a salicylanilide and levamisole. Moxidectin and levamisole were effective against this strain of H. contortus and reduced the arithmetic mean burdens of this parasite in the sheep by 99.98% and 99.59%, respectively, while the efficacy of ivermectin, albendazole and closantel was only 29.1%, 33.75% and 78.3%, respectively.

Topics: Albendazole; Animals; Anthelmintics; Anti-Bacterial Agents; Drug Resistance; Haemonchiasis; Haemonchus; Ivermectin; Levamisole; Macrolides; Salicylanilides; Sheep; Sheep Diseases