PREVALENCE OF INTESTINAL PARASITES AND ANTI-HELMINTH RESISTANCE IN FERAL POPULATIONS IN ARIZONA

Abstract

Semi-managed animal populations, such as barn cats and feral donkeys, occupy a unique space between domestic care and environmental exposure, placing them at ongoing risk for gastrointestinal parasite transmission. This thesis evaluated parasite prevalence, diagnostic method performance, and management implications in barn cats and rescued feral donkeys across Arizona. Fecal samples from barn cats (n=22) were analyzed using both passive flotation and centrifugal flotation (CFS) methods. Results yielded a prevalence of 9.1% Hookworms and 0% prevalence for remaining parasites. All positive cases were detected using CFS, while passive flotation failed to identify any infections. An intraclass correlation coefficient (ICC) analysis demonstrated low agreement between tests (ICC = -2.3 × 10^-15; 95% CI: -0.400 to 0.408), suggesting the two methods produced inconsistent egg count results overall. These findings highlight the importance of selecting sensitive diagnostic tools when screening semi-managed feline populations with low to moderate parasite burdens. Donkey fecal samples (n=36) were examined using the Modified Wisconsin and McMaster techniques to quantify strongyle-type and ascarid eggs. Strongyles were the most prevalent, with 63.9% of samples testing positive across both methods. Ascarid detection ranged from 22.2-38.9%, depending on method. The Cliff's Delta value was -0.25, indicating a small negative effect size, meaning that the Modified Wisconsin method tends to underestimate Ascarids compared to the McMasters. Additionally, the Bland-Altman plot for Ascarids revealed this negative bias appeared to increase with higher Ascarid counts, showing a proportional underestimation by Wisconsin for larger counts. After administration of oral Ivermectin, the Fecal Egg Reduction Count Test revealed 100% reduction for Ascarids and 0% for Strongyles, revealing evidence of Ivermectin resistance in Strongyles. These findings emphasize the need for species-specific diagnostic strategies, tailored deworming protocols, and regular resistance monitoring in semi-managed animal populations.