Abstract The studies within this thesis have made a valuable contribution to our understanding of anthelmintic resistance in Scotland and in particular to the prevalence of benzimidazole BZ and ivermectin IVM resistance, the expression of multiple resistance and its management. Anthelmintic resistance in sheep flocks in Ontario, Canada. In spite of great efforts making vaccines protecting grazing animals against helminth infections, only a vaccine against the bovine lungworm Dictyocaulus viviparus is commercially available [ 42 ]. Anthelmintic resistance detection methods. Comparison of thiabendazole, ruelene, and phenothiazine. In this report BZ-resistance was detected in four out of 26 herds.

A survey on resistance to anthelmintics in sheep stud farms of southern Brazil. Different in vitro methods are described. Please review our privacy policy. The nematode strains resistant to benzimidazole were highly susceptible to imidazothiazoles, but in Australia, Le Jambre et al. Survey of anthelmintic resistance on Danish horse farms, using 5 different methods of calculating faecal egg count reduction. Thus, the purpose of this review is to provide an overview of the reports of AHR in small ruminants in Brazil, discussing the history and forms of diagnosis employed; and to analyze the distribution of surveys by region, as well as the evolution of the use, effectiveness and maintenance of these drugs over the years.

Vet Parasitol ; 81 3: N Z Vet J ; 54 6: Rev Bras Zootec ; 39 suppl spe. Anthelmintic resistance of gastrointestinal parasites in small ruminants. In spite of the fact that the benzimidazoles and levamisole have been used over the same period of time, the resistance to these drugs was detected much later in New Zealand [ 11 ].

anthelmintic resistance dissertation

For horses a reasonable aim of a parasite control program would be to eliminate the large strongyles and have the cyathostomes and Parascaris equorum infestations under control. Cienc Rural ; 33 2: In their study, levamisole showed superior performance, and was found to be effective on 10 farms. Non chemical control of helminths in ruminants: The drugs most commonly evaluated in sheep and goats consist of various formulations of benzimidazoles the first anthelmintics to be studiedlevamisole, ivermectin, moxidectin, closantel, and associations of these drugs.


The sheep flocks are directed at products with high added value, and currently stand out in the production of special lamb cuts. Molecular based tests are only in use for detection of BZ resistance as the molecular mechanisms for resistance to tetrahydropyrimidenes and macrocyclic lactones are not fully understood [ 18 ].

Anthelmintic resistance. An overview of the situation in the Nordic countries

Drug resistance in nematodes of veterinary importance. A survey on resistance to anthelmintics in sheep stud farms of southern Brazil. Table 2 presents a compilation of surveys on AHR in small ruminants in Brazil over timelisting the drugs that have shown a higher effectiveness ratio than the other studied drugs. AHR problems were reported in a broad study by Ramos et al.

Edinburgh Research Archive

In Brazil, the productive potential for ruminants that are suitable for animal husbandry is hampered by antuelmintic infections. The controlled reduced parasitic load test, which is performed after the autopsy of the animal, evaluates the real situation of parasite elimination in the host WOOD et al. Later Maingi et al.

Conference Parasite infections of domestic animals in the Nordic countries — emerging threats and challenges. The higher the proportion of parasites in refugia the slower the development of resistance as the selection pressure of the whole population is lower [ 89 ]. In the same year, Vieira et al.

Overview of anthelmintic resistance of gastrointestinal nematodes of small ruminants in Brazil

dissertattion In the latter study, H. Exp Parasitol ; 95 4: Haemonchus contortusAust Vet J ; 57 2: Argentina EDDI et al. Onderspoort J Vet Res. The frequency of use and the maintenance of the effectiveness of anthelmintics over the years are important factors in understanding resistance mechanisms, but are only scantily reported in current studies.


Braz J Vet Parasitol ; 17 1: In the 90s, Amarante et al. The large number of studies on AHR in Brazil reflects the concern of the country, which has production potential and seeks to organize the sheep and goat production chain.

Anthelmintic resistance. An overview of the situation in the Nordic countries

Efficacy of monepantel, derquantel and abamectin against adult stages of a multi-resistant isolate. The most obvious way to reduce the exposure is to reduce the use of anthelmintic drugs and look to other ways to control parasites beside anthelmintic use.

Resistance will develop if there are survival advantages for parasites carrying dissetration alleles [ 7 ]. Therefore, the consensus of the scientific community is that, in view of the high vulnerability of the effectiveness of anthelmintics, allopathic treatment should not be the only form of antiparasitic treatment, and that the focus should be on correlating animal handling, nutrition and alternative forms of parasite control.

anthelmintic resistance dissertation

Pyrantel resistance in small strongyles has also been reported from the Nordic countries [ 30 – 32 ]. The authors concluded that multiple resistance to anthelmintics is already established in most sheep herds in MS, and that the species Haemonchus contortus and Trichostrongylus colubriformis are the most prevalent and resistant to antiparasitics.