Suspected ivermectin resistance in a south-east Queensland Parascaris equorum population.

The research article documents a case of suspected resistance to the anthelmintic drug ivermectin in a population of Parascaris equorum, a type of parasitic worm, in south-east Queensland, Australia.

Background of the Study

• The study investigates an instance of suspected resistance to ivermectin in a population of Parascaris equorum in south-east Queensland, Australia.
• Parascaris equorum is a type of parasitic worm that affects horses, particularly young ones like foals.
• Ivermectin is a macrocyclic lactone (ML), a class of drugs used as anthelmintics or worm-killing agents in animals.
• While there have been international reports of ML-resistant P. equorum populations, the resistance status of Australian populations has been largely unknown until now.

Investigation and Results

• A faecal egg count reduction test was conducted to evaluate the efficacy of ivermectin.
• This test involved comparing the number of P. equorum eggs present in the feces of a group of weanling foals before and after treatment with ivermectin.
• The test revealed a 65% efficacy rate for ivermectin, suggesting a reduced efficiency against P. equorum in the tested population.

Conclusions and Recommendations

• The study concludes that there is a case of apparent reduced efficacy of ivermectin against P. equorum in Australia.
• This case highlights the need to review and possibly revise current worm control strategies, particularly for young horses like foals.
• As resistance to ivermectin compromises its effectiveness as a means of controlling P. equorum infections, alternative treatment or management practices may required.