Susceptibility of helminth species parasites of sheep and goats to different chemical compounds in Brazil

Abstract

A total of 160 sheep and 160 goats were necropsied to evaluate the degrees of susceptibility or resistance of different helminth species to 0.2 mg/kg ivermectin (subcutaneous route), 0.2 mg/kg moxidectin (subcutaneous route), 100 mg/kg trichlorfon (administered orally) and the combination of 5 mg/kg albendazole + 7.5 mg/kg levamizole + 0.2 mg/kg ivermectin (administered orally). To achieve this objective, eight experiments were performed, four with each animal species. In each experiment, naturally infected sheep or goats were divided into five groups with eight individuals each, as follows: T01, untreated control; T02, trichlorfon; T03, ivermectin; T04, moxidectin; and T05, albendazole + levamizole + ivermectin, based on average counts of eggs per gram of feces (EPG) before treatment (experimental dates −3, −2 and −1). Seven days post-treatment (DPT), all animals were euthanized and necropsied for the recovery of helminth burdens. Based on the obtained results, it is possible to conclude that the resistance of some helminth species parasitizing sheep and goats is different for the tested chemical groups. Ivermectin, at 0.2 mg/kg dosage, presented inferior anthelmintic efficacy against some of these parasites. Of these species, populations of Haemonchus contortus, followed by Trichostrongylus colubriformis, Cooperia curticei and Oesophagostomum columbianum, exhibited the greatest resistance to the aforementioned chemical compound, whereas Trichostrongylus axei displayed higher susceptibility to ivermectin. For moxidectin (0.2 mg/kg), 75% of all H. contortus populations were considered resistant to this drug, whereas all populations of T. colubriformis, T. axei, C. curticei and O. columbianum were susceptible. Trichlorfon and albendazole + levamizole + ivermectin were effective against the analyzed nematode populations, except against one strain of H. contortus and one strain of T. colubriformis. All three Strongyloides papillosus populations evaluated were susceptible to the tested formulations, except for moxidectin, as this compound presented low efficacy indices against all populations of this helminth species.

First evaluation and detection of ivermectin resistance in gastrointestinal nematodes of sheep and goats in South Darfur, Sudan

“…Ivermectin was found to be effective against another identified nematode, S. papillosus, in goats in Bulbul and Nyala University farm. This is an interesting finding as the results of many studies from different regions supported our finding and detected no S. papillosus eggs in faeces of sheep and goats after ivermectin treatment [57][58][59].…”

Effect of growing forage legumes on the migration and survival in the pasture of gastrointestinal nematodes of sheep

“…Today, the main obstacle to the productive efficiency of sheep grazing is gastrointestinal nematodes (GIN), which cause significant productivity and financial losses and impair the well-being of these animals (Charlier et al, 2014;Raineri et al, 2015;Oliveira et al, 2017). The inappropriate use of anthelmintics as the main strategy to reduce parasite burdens has led to the emergence of parasite populations resistant to most of the active ingredients used in chemical control, rendering them ineffective (Neves et al, 2014;Bichuette et al, 2015). Environmental contamination and chemical residues of synthetic anthelmintics pose a threat to ecological dynamics and a serious risk to public health (Beynon, 2012;Beynon et al, 2012;Silva et al, 2012;Siroka & Svobodova, 2013;Köksal et al, 2016;Goodenough et al, 2019).…”

Anthelminthic resistance of gastrointestinal nematodes in sheep to monepantel treatment in central region of Rio Grande do Sul, Brazil

“…This nematodes have developed resistance to the most common drugs available (benzimidazoles and macrocyclic lactones) which is recognized by the increase number of treatments needed to control them in small ruminants (Waller et al 1996, Wolstenholme et al 2004. Different studies have reported this lack of efficacy of different chemical groups, such reports include the studies of Cezar et al (2010), Borges et al (2015), and Bichuette et al (2015) in the states of Rio Grande do Sul, Bahia, and São Paulo respectively.…”