Anthelmintic Resistance In Gastrointestinal Nematodes Of Sheep
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Date
2014-03
Journal Title
Journal ISSN
Volume Title
Publisher
TANUVAS, Chennai
Abstract
Anthelmintics are used traditionally as an integral part of helminthic
control strategies for grazing livestock to prevent production losses from
parasitic infections. The continuous and indiscriminate use of the same
anthelmintics over years together as the sole means of control are now failing
due to the emergence of resistance strains of helminths. Resistance to the
commonly used anthelmintics in gastrointestinal nematodes of sheep has
become an increasingly wide spread problem throughout the world. The present
study was aimed to determine the resistance against albendazole, fenbendazole,
levamisole and closantel in gastrointestinal nematodes of sheep. Fifty five
naturally infected Madras Red lambs of 6 - 12 months of age were selected
and distributed randomly into five treatment groups of eleven animals each.
Four groups were treated orally with albendazole (5mg/kg), fenbendazole (7
mg/kg), levamisole (7.5m/kg) and closantel (10 mg/kg) respectively, while the
fifth group served as untreated control. Faecal samples were collected per
rectum of each lamb just prior to treatment (pre treatment) and then on days
7, 14, 21 and 28 after treatment. The anthelmintic resistance was evaluated by
in vivo faecal egg count reduction test (FECRT), post treatment larval culture
and in vitro egg hatch assay. In the faecal egg count reduction test, albendazole
reduced the faecal egg count by 86.50 per cent, 84.81 per cent, 85.28 per cent
and 84.47 per cent respectively for four weeks after treatment. Faecal egg
count reduction using fenbendazole was 92.64, 93.04, 90.80 and 90.06 per
cent respectively for four weeks after treatment. The per cent efficacy for
levamisole and closantel was more than 95 per cent. The post treatment larval
culture contained only Haemonchus contortus. In the in vitro egg hatch assay,
the ED50 value for benzimidazole was 0.299 μg thiabenazole/ml and levamisole
showed an ED50 value of 0.283 μg /ml.
Description
Keywords
Veterinary Science, Veterinary Parasitology