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

Abstract

Frequent and inappropriate use of all classes of antiparasitic drugs in small ruminants has led to failures in their effectiveness, culminating in a global problem of anthelmintic resistance. Brazil stands out as one of the world's leaders in publications about anthelmintic resistance, and for having the most numerous reports of this resistance in small ruminants in the Americas. These studies have involved mainly the fecal egg count reduction test (FECRT) and its correlation with field management practices. In vivo effectiveness testing is conducted in areas where livestock is of greater economic significance, e.g., in the South (sheep) and Northeast (goats), or is important for research and economic centers, such as the Southeast (sheep). The most widely studied species is sheep, for which the widest range of drugs is also evaluated. Despite significant advances achieved in molecular research, laboratory analyses should include knowledge about the reality in the field so that they can become feasible for the producer. Moreover, molecular studies can be underpinned by the analysis of field studies, such as the maintenance of antiparasitic effectiveness over time and the mechanisms involved in this process.Keywords: Small ruminants, anthelmintic resistance, sheep, goat, gastrointestinal nematodes. ResumoO uso frequente e inapropriado de todas as classes de antiparasitários em pequenos ruminantes levou a falhas de eficácia, culminando na problemática global de resistência anti-helmíntica. O Brasil destaca-se como sendo um dos pioneiros nas publicações com resistência anti-helmíntica no mundo e por ter o maior número de relatos em pequenos ruminantes na América. Essas pesquisas envolvem principalmente o teste da redução da contagem de ovos nas fezes (TRCOF) e sua correlação com as práticas de manejo utilizadas no campo. Os estudos de testes de eficácia in vivo localizam-se em áreas onde há maior importância dos rebanhos como nas Regiões Sul (ovinos) e Nordeste (caprinos), ou com importância em polos de pesquisa e econômicos, como a região Sudeste (ovinos). Ovina é a espécie mais estudada e com maior gama de drogas avaliadas. Mesmo com grande avanço em pesquisas moleculares, as análises laboratoriais devem envolver o conhecimento da realidade do campo para que possam se tornar viáveis ao produtor. Além disso, a análise dos estudos de campo pode nortear estudos moleculares como, por exemplo, a manutenção da eficácia das drogas ao longo dos anos e os mecanismos envolvidos em tal processo.

Multiple resistances of gastrointestinal nematodes to anthelmintic groups in cattle of semiarid of Paraíba, Brazil

“…In Brazil, the most commonly used anthelmintics belong to three families: benzimidazoles, imidozotiazoles, and macrocyclic lactones. However, none of these drugs are effective for treating ruminant animals infected with gastrointestinal nematodes, especially Haemonchus contortus (Salgado and Santos, 2016). Few studies have investigated anthelmintic resistance in gastrointestinal nematodes of cattle in northeastern Brazil.…”

Ovicidal and larvicidal potential of Rosmarinus officinalis to control gastrointestinal nematodes of sheep

“…Attempts to reduce losses have led to significantly increased frequency and doses applied in anthelmintic treatments, causing irreversible resistance of GIN to practically all the available active ingredients (SALGADO & SANTOS, 2016). Haemonchus contortus stands out among these parasites, mainly due to its hematophagous nature and high prolificacy of females (GETACHEW et al, 2007).…”

Can the strategies for endoparasite control affect the productivity of lamb production systems on pastures?

“…The consequence of this is the strong selection pressure for homozygous resistant parasites and the loss of heterozygosity to the local populations (Fortes and Molento, 2013). Therefore, Salgado and Santos (2016) reported one of the highest anthelmintic resistance to all chemical groups in Brazil, and improved strategies for parasite control are needed. In addition, the excessive and indiscriminate use of veterinary drugs might result in residues in meat, milk, and the environment, which is relevant to the current production context (Fernandes et al, 2017).…”