First report of multiple anthelmintic resistance in nematodes of sheep in Colombia

Abstract

This study aimed to report the presence of parasites resistant to the most used anthelmintic drugs in sheep in Colombia. Four farms (denominated farm 1, 2, 3 and 4) were selected where the animals were not treated with anthelmintics for two months before the trial. Animals with faecal egg count (FEC) above 150 and of different ages were allocated into six groups, each consisting of at least 5 animals. The drugs and dosages used were: ivermectin 1% (0.2 mg/kg), albendazole 25% (5 mg/kg), fenbendazole 10% (5 mg/kg), levamisole 10% (5 mg/kg), and moxidectin 1% (0.2 mg/kg). Anthelmintic effi cacy was determined by the FEC reduction test (FECRT) with a second sampling 14 days post-treatment. The effi cacy of albendazole and fenbendazole at farm 1 was above 95%, which was different from the others farms. The FECRT indicated the presence of multidrug resistance in the other farms where no tested drugs showed activity higher than 79% (albendazole: 0 to 55%, fenbendazole: 51.4 to 76.6%, ivermectin: 67.3 to 93.1%, levamisole: 0 to 78.1%, and moxidectin: 49.2 to 64.1%). Haemonchus contortus was the predominant (96%) species, followed by a small presence of Trichostrongylus sp. (3%) and Cooperia sp. (1%). Therefore, we report for the fi rst time the existence of multiple anthelmintic resistance in gastrointestinal nematodes of sheep in Colombia.

Prospects for elimination of soil-transmitted helminths

“…Anthelmintic resistance, including multidrug resistance [85], is a well documented issue in animal populations [86] and some mutations associated with benzimidazole resistance have been identified in eggs from human stool [87]. Although any largescale MDA with benzimidazoles may risk producing resistance [54], in animal husbandry, strategies to combat resistance include the exclusion of a subset of the population from deworming to maintain refugia [88,89].…”

Resistance to monepantel in multiresistant gastrointestinal nematodes in sheep flocks in Rio Grande do Sul

“…Only 7.5% of the properties did not present detectable levels of anthelmintic resistance. Gárcia et al (2016) determined the efficacy of ivermectin, albendazole, fenbendazole, and levamisole, and observed that animals in properties in Colombia were resistant to all tested active ingredients.…”

“…The short interval between treatments, suppressive treatments, rapid alternation of different active principles, introduction of animals with resistant parasites in the flock, and the excessive, indiscriminate, and continued use of long-acting anthelmintic drugs as control methods favor the development of isolates of parasites resistant to anthelmintic drugs, and this phenomenon has been reported in Brazil and overseas (ECHEVARRIA et al, 1996;NARI et al, 1996;BESIER;LOVE, 2003;WAGHORN et al, 2006;ROSALINSKI-MORAES et al, 2007;HOWELL et al, 2008;ALMEIDA et al, 2010;SCZESNY-MORAES et al, 2010;COSTA et al, 2011;HOLSBACK, et al, 2013;GEURDEN et al, 2014;GÁRCIA et al, 2016). These measures result in increased costs with ineffective treatments and may jeopardize sheep farming.…”

Anthelmintic activity of Artemisia annua in sheep-model

“…Small ruminant infections are controlled by using the commercially available chemicals. However, there are various reports of multidrug-resistant in small ruminant nematodes throughout the world (Veríssimo et al, 2012;Chagas et al, 2013;Gárcia et al, 2016;Keegan et al, 2016). Unfortunately, the strong selection pressure that has been imposed associated with incorrect frequency and doses are responsible for the anthelmintic inefficacy of the available chemical groups (Soares et al, 2009).…”