Resistance to macrocyclic lactones

Area of Science:

• Veterinary Parasitology
• Antimicrobial Resistance
• Livestock Health

Background:

• Macrocyclic lactones (MLs) are vital for controlling parasitic infections in livestock.
• Increasing resistance to MLs in target organisms like nematodes poses a significant threat to animal health and agricultural productivity.
• Severe ML resistance is already impacting small ruminants, horses, and cattle.

Purpose of the Study:

• To highlight the escalating problem of macrocyclic lactone resistance in livestock parasites.
• To emphasize the urgent need for a better understanding of ML resistance mechanisms, especially in nematodes.
• To discuss challenges in distinguishing true resistance from treatment failures and the need for improved diagnostic assays.

Main Methods:

• Review of current knowledge on ML resistance in veterinary parasites.
• Analysis of factors contributing to treatment and prophylaxis failures.
• Evaluation of proposed strategies for sustainable anthelmintic drug use in livestock farming.

Main Results:

• ML resistance is a confirmed and escalating issue in various livestock species, severely compromising parasite control.
• There is a significant knowledge gap regarding the specific mechanisms of ML resistance in nematodes.
• Distinguishing true resistance from other causes of drug failure is difficult, necessitating the development of more robust diagnostic tools.

Conclusions:

• Sustainable use of MLs depends on improved understanding of resistance and implementation of strategic drug administration.
• Developing and refining diagnostic assays for ML resistance is critical.
• Adoption of improved drug use schemes is essential to mitigate the growing threat of ML resistance in livestock parasites.