Implication of the fecal egg count reduction test (FECRT) in sheep for better use of available drugs.

Jordana Andrioli Salgado,Cristina Santos Sotomaior,Clóvis De Paula Santos,Letícia Oliveira Da Rocha,Tâmara Duarte Borges,Letícia Vidal Cruz

doi:10.1590/s1984-29612019093

Abstract

The aim here is to present data on the efficacy of anthelmintics in sheep flocks in Rio de Janeiro, Brazil, and to discuss the interpretation of the fecal egg count reduction test (FECRT) for each nematode genus. Fecal eggs counts and pre- and post-treatment coprocultures were performed, the former to evaluate the efficacy of and the latter to determine the overall parasite prevalence. An additional efficacy test was performed at Farm # 1 a year after the initial test. Severe anthelmintic resistance was found for the flocks, with no FECRT sensitivity at any of the 22 farms evaluated. However, an analysis of the infective larvae showed that some drugs were effective against certain parasitic genera; i.e., levamisole was more effective against Haemonchus spp. and moxidectin against Trichostrongylus spp. In the additional FECRT performed at Farm # 1, moxidectin and nitroxynil were ineffective separately, but when applied in combination they were highly effective due to their efficacy against Haemonchus (nitroxynil) and Trichostrongylus (moxidectin), respectively. The use of the FECRT targeting the parasitic nematode species prevalent on farms may make it possible to choose more effective anthelmintics.

Highlights

The main health issue affecting sheep around the world is gastrointestinal nematode infection (CHARLIER et al, 2014)
701/707 701 resistance (AHR) to the various classes of drugs in sheep is reported in several regions of the world (TORRES‐ACOSTA et al, 2012; GEURDEN et al, 2014; SALGADO & SANTOS, 2016), including to those most recently launched on the market (SCOTT et al, 2013; CINTRA et al, 2016)
Sheep are hosts to a wide variety of gastrointestinal nematodes that cause clinical symptoms depending on the prevalence of each species, which varies as a function of climate and herd management system (ROSE VINEER et al, 2016)

Summary

Introduction

The main health issue affecting sheep around the world is gastrointestinal nematode infection (CHARLIER et al, 2014). 701/707 701 resistance (AHR) to the various classes of drugs in sheep is reported in several regions of the world (TORRES‐ACOSTA et al, 2012; GEURDEN et al, 2014; SALGADO & SANTOS, 2016), including to those most recently launched on the market (SCOTT et al, 2013; CINTRA et al, 2016). Sheep are hosts to a wide variety of gastrointestinal nematodes that cause clinical symptoms depending on the prevalence of each species, which varies as a function of climate and herd management system (ROSE VINEER et al, 2016). Identifying parasite populations in the herd has become increasingly important in monitoring the spread of AHR in target nematode species and to keep track of changes in parasite prevalence resulting from climate variations (ROEBER et al, 2017)

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Conclusion