Investigation of the Efficacy of Pyrantel Pamoate, Mebendazole, Albendazole, and Ivermectin against Baylisascaris schroederi in Captive Giant Pandas

SIMPLE SUMMARY: Giant pandas are key protected animals in China. Baylisascaris schroederi, a parasitic nematode, is one of the main health risks threatening them. We used four anthelmintics—pyrantel pamoate (PYR), mebendazole (MBZ), albendazole (ABZ), and ivermectin (IVM)—on 22 enrolled giant pandas. The fecal egg count reduction (FECR) proportions were calculated using both the Markov chain Monte Carlo (MCMC) Bayesian mathematical model and the arithmetic mean based on fecal egg count data. Anthelmintic resistance (AR) was assessed based on the criteria recommended by the World Association for the Advancement of Veterinary Parasitology (WAAVP). We found that the nematode was suspected to be resistant to PYR. The number of eggs per gram in the feces of giant panda enrolled in the present study was increased near the end of the experiment. ABSTRACT: Baylisascaris schroederi is one of the main health risks threatening both wild and captive giant pandas. The administration of anthelmintics is a common method to effectively control B. schroederi infection, but there is a notable risk of anthelmintic resistance (AR) after long-term, constant use of anthelmintics. Four anthelmintics—pyrantel pamoate (PYR), mebendazole (MBZ), albendazole (ABZ), and ivermectin (IVM)—were each administered separately at intervals of 2 months to 22 enrolled giant pandas. The fecal egg count reduction (FECR) proportions were calculated by both the Markov chain Monte Carlo (MCMC) Bayesian mathematical model and the arithmetic mean. AR was assessed based on the criteria recommended by the World Association for the Advancement of Veterinary Parasitology (WAAVP). The estimated prevalence of B. schroederi infection was 34.1%. After treatment with PYR, MBZ, ABZ, and IVM, it was determined that MBZ, ABZ, and IVM were efficacious against B. schroederi, while nematodes were suspected to be resistant to PYR according to the fecal egg count reduction (FECR) proportions.