Anthelmintic resistance in strongylids (Nematoda: Strongylidae) parasitizing wild and domestic equids in the Askania Nova Biosphere Reserve, Ukraine.

The study investigates the resistance of parasitic worms in wild and domestic horses to common deworming drugs in Ukraine’s Askania Nova Biosphere Reserve. It reveals that due to the long-term exposure to the drugs, the worms have become increasingly resistant, reducing the effectiveness of treatments over time.

Research Objectives and Methodology

• The research was carried out to analyze the development of resistance in strongylid parasites – a type of roundworm – in both domestic and wild horses in the Askania Nova Biosphere Reserve in Ukraine.
• This study involved four species of horses – domestic horses, Shetland ponies, zebras, and donkeys – that were kept under semi-free conditions.
• The team of researchers used the Fecal Egg Count Reduction Test (FECRT) to observe the presence of resistance to benzimidazole anthelmintics (BZ), a type of deworming drug.

Results

• The examination of data collected over a decade (between 2009 to 2019) revealed the declining efficiency of BZ drugs on strongylids in these four horse species.
• The study discovered a reduction in the efficacy of deworming treatments from 97.6% in 2009 to less than 75% in 2019.
• In terms of species, the anthelmintic treatment was least effective in donkeys at 45.2%, followed by ponies (61.1%), domestic horses (66.4%), Grévy’s zebra (72.7%), and plains zebras (69.4%).
• Post-deworming analysis revealed the presence of ten different types of cyathostomins (a species of roundworm) in the horses treated with the drug albendazole.

Significance of the Results

• The findings of this study indicate, for the first time, the development of BZ-resistance in the wild horse population kept under semi-free conditions in the Askania Nova Biosphere Reserve.
• This research’s implications highlight the urgent need for improved parasite control methods to maintain the health of equid populations in controlled habitats such as a biosphere reserve.