University of Khartoum

Applications of anthelmintic resistance tests for gastrointestinal nematodes of sheep in the sudan

Applications of anthelmintic resistance tests for gastrointestinal nematodes of sheep in the sudan

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Title: Applications of anthelmintic resistance tests for gastrointestinal nematodes of sheep in the sudan
Author: Suliman, Gundi
Abstract: The present study was conducted mainly for evaluation and tackling the problem of anthelmintic resistance and the appropriate tests of measuring it in the field under Sudan condition. A survey of gastrointestinal nematodes of sheep was made and 339 visceral organs and 307 faecal samples were examined during the period 1999-2002. Adult nematodes species identified from visceral organs contents were; Haemonchus contortus, Oesophagostomum columbianum, Strongyloides papillosus and Trichuris ovis from both sheep and goats. In addition Trichostrongylus probolurus, Impalaia tuberculata and the trematode Dicrocoelium dendriticum were reported in sheep for the first time in Sudan.The identification of the infective third stage larvae from faecal cultures revealed the following; Haemonchus contortus, Oesophagostomum columbianum, Strongyloides papillosus and Trichostrongylus spp. The importance of wild ruminants and camels on the epidemiology of gastrointestinal parasites of sheep is discussed. A survey of anthelmintic resistance was made using the in vivo and in vitro methods. In the in vivo method of detecting anthelmintic resistance, the faecal egg count reduction test was used (FECRT). Thirty six naturally parasitized adult sheep were used. Animals were divided into four groups; a control group and the remaining three groups received anthelmintics at day (0) according to the manufacturers recommend dose rates; 1 ml/50 kg body weight Ivomec 1%; 5mg/kg body weight albendazole and 1200 mg/50 kg body weight levamisole. Faecal samples were collected at day (0) and day (14) post treatment and all animals were necropsied on day (14) post treatment. The faecal egg count reduction test calculation was performed for all groups and the results showed 100% efficacy for both ivomec injection and levamisole bolus, 13 whereas the albendazole showed efficacy of 97% which is considered as low resistance according to the guide lines of the World Association of the Advancement of Veterinary Parasitology (W.A.A.V.P.). In the in vitro test of anthelmintic resistance, the egg hatch assay and larval development test were carried for the experimental animals using ivomec and thiabendazole for each test. The ED50 obtained from the egg hatch assay is, 0.796 ng/ml using ivomec injection and > 0.1 μg/ml using thiabendazole. The ED50 obtained from the larval development test is 0.769 ng/ml using ivomec injection and >0.1μg/ml using albendazole drench. These in vitro tests confirm the results obtained in the in vivo test when the faecal egg count reduction test was used in the experimental animals. The egg hatch paralysis assay and the larval paralysis assay were performed on composite faecal sample collected from naturally infected sheep, using albendazole drench and levamisole bolus. The ED50 of egg hatch paralysis assay obtained for both albendazole and levamisole were 3.596 μg/ml and 3.69 μg/ml respectively. The larval paralysis assay using levamisole failed to obtain ED50 values in the present study. We conclude from the present study and recommend the use of egg hatch and larval development assays for field monitoring of anthelmintic resistance of sheep nematodes in Sudan. The test should be carried in conjunction with the in vivo faecal egg count reduction test for larval identification, comparison and correlation of the in vivo and in vitro results.
URI: http://hdl.handle.net/123456789/8250
Date: 2015-04-05


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