monepantel and Intestinal-Diseases--Parasitic

To determine the efficacy of monepantel, a developmental compound from the amino-acetonitrile derivative class of anthelmintics, against field infections of gastrointestinal nematodes in sheep.. Comparisons of efficacy (using standard faecal worm egg count reduction tests) and safety (on the basis of visual observations) were made in a large-scale field study in Australia, between groups of sheep treated with either an oral solution of monepantel or a registered anthelmintic. The sheep were naturally infected with the major gastrointestinal nematode genera present in Australia.. The post-treatment efficacy results for monepantel were: at 7 days (+/-1 day) efficacy was >98%; at 14 days (+/-1 day) it was generally close to or >99%; and at 21 days (+/-1 day) efficacy was consistently >99%. A high proportion of the targeted nematode populations were confirmed as being resistant to one or more of the currently available anthelmintic classes.. Monepantel when used under field conditions at a minimum dose rate of 2.5 mg/kg was highly effective against mixed-genus natural field infections of the major gastrointestinal nematode genera including Haemonchus, Teladorsagia (Ostertagia), Trichostrongylus, Nematodirus, Chabertia and Oesophagostomum. This result included efficacy against some populations resistant to the currently available broad-spectrum anthelmintics. Few Cooperia spp. were present to allow confirmation of efficacy against this genus. On no occasion after treatment did any commercial anthelmintic-treated groups have significantly lower faecal egg counts than the monepantel-treated groups. Monepantel was safe for the target animals and human operators when used in a field situation.

Topics: Aminoacetonitrile; Animals; Anthelmintics; Australia; Drug Resistance; Feces; Female; Helminthiasis, Animal; Intestinal Diseases, Parasitic; Male; Parasite Egg Count; Sheep; Sheep Diseases; Treatment Outcome

Endoparasites are considered a major health problem of South American camelids as shown in a recent survey among German and Austrian camelid owners. Although prophylactic and therapeutic measures such as application of anthelmintics are commonly used, treatment efficacy is usually not assessed. Owners have expressed significant concerns regarding the effect of antiparasitic therapy, so this study aimed to evaluate the outcome of anthelmintic treatment in German alpaca herds with different drugs.. Overall, 617 samples from 538 clinically healthy alpacas > 1 year-old from 27 farms (n = 11-157 animals/herd) were examined. The most common parasites detected by flotation were Eimeria spp. (75.1%) followed by strongylids (55.0%), Nematodirus spp. (19.3%), cestodes (3.1%) and Trichuris (2.7%). After initial coproscopical examination by flotation and strongylid egg quantification by the McMaster technique, positive animals excreting at least 150 eggs per gram of faeces were included in a faecal egg count reduction test (FECRT) using fenbendazole (n = 71 samples), moxidectin (n = 71) or monepantel (n = 66). Pre-treatment larval cultures (n = 23 positive pooled farm samples) revealed Haemonchus (87% of the farms), Cooperia (43.5%), Trichostrongylus (21.7%), Ostertagia (13.0%), Nematodirus and Oesophagostomum (4.3% each). Fenbendazole treatment reduced egg excretion by 45%, moxidectin by 91% and monepantel by 96%. On the farm level, 13/18 farms that used fenbendazole, 6/6 farms that used moxidectin and 2/5 farms that used monepantel had individual FECR values < 90% (fenbendazole) or < 95% (moxidectin, monepantel). Haemonchus and Cooperia were overrepresented on the farms with reduced treatment efficacy.. Gastrointestinal strongylids are common in German alpacas and fenbendazole in particular was not sufficiently effective to reduce strongylid egg excretion. Although the FECRT could not unambiguously determine anthelmintic resistance in the present study, the finding that small ruminant strongylids, especially Haemonchus, are common in alpacas indicates that determination of effective anthelmintic doses, monitoring of efficacy and adapted (selective) treatment regimens must be implemented as part of sustainable deworming practices in this species in accordance with recommendations for ruminants.

Topics: Aminoacetonitrile; Animals; Anthelmintics; Camelids, New World; Feces; Female; Fenbendazole; Haemonchus; Helminthiasis, Animal; Intestinal Diseases, Parasitic; Macrolides; Male; Parasite Egg Count; Strongylida; Strongylida 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

Monepantel is the first compound from the recently discovered amino-acetonitrile derivative (AAD) class of anthelmintics to be developed for use in sheep. Nine dose confirmation studies were conducted in Australia, New Zealand and Switzerland to confirm the minimum therapeutic oral dose of monepantel to control fourth stage (L4) gastro-intestinal nematode larvae in sheep (target species were Haemonchus contortus, Teladorsagia (Ostertagia) circumcincta, Teladorsagia trifurcata, Trichostrongylus axei, Trichostrongylus colubriformis, Trichostrongylus vitrinus, Cooperia curticei, Cooperia oncophora, Nematodirusbattus, Nematodirusfilicollis, Nematodirus spathiger, Chabertia ovina and Oesophagostomum venulosum). In each study, sheep infected with a defined selection of the target nematodes were treated with 2.5mg monepantel/kg liveweight. Following euthanasia and worm counting, efficacy was calculated against worm counts from untreated control groups. The results demonstrate high (95<100%) efficacy of monepantel when administered orally to sheep at 2.5mg/kg for most species tested. Efficacy levels against N. spathiger and O. venulosum were variable and failed to meet the required regulatory standard (> or =90%) in some studies. Efficacy was demonstrated against L4 stages of nematodes known to be resistant to either benzimidazole and/or levamisole anthelmintics (macrocyclic lactone resistant isolates were not available for testing). The broad-spectrum activity of monepantel against L4 larvae of common gastro-intestinal nematodes in sheep and its favorable safety profile represents a significant advance in the treatment of parasitic gastro-enteritis in this animal species. No adverse effects related to treatment with monepantel were observed.

Topics: Aminoacetonitrile; Animals; Antinematodal Agents; Dose-Response Relationship, Drug; Female; Intestinal Diseases, Parasitic; Larva; Male; Nematoda; Nematode Infections; Parasite Egg Count; Parasitic Sensitivity Tests; Sheep; Sheep Diseases; Species Specificity; Treatment Outcome