Comparison of Serological Detection Methods for Toxoplasma gondii Antibodies and Seroprevalence in Captive Red Pandas

Toxoplasma gondii is a globally distributed zoonotic parasite that infects a wide range of warm-blooded animals and poses serious threats to many endangered species. Effective serological detection is critical for disease surveillance and control, yet the accuracy of commercial assays varies significantly across host species. Validated serological methods for the Chinese red panda (Ailurus styani) remain scarce, limiting effective monitoring and conservation efforts. A total of 57 serum samples were collected from captive red pandas. Three commercial serological kits-the modified agglutination test (MAT), indirect hemagglutination assay (IHA), and enzyme-linked immunosorbent assay (ELISA)-were used to detect T. gondii antibodies. Statistical analyses included agreement assessment (Cohen's kappa), McNemar's test, and receiver operating characteristic (ROC) curve analysis, with MAT as the reference standard. MAT detected T. gondii antibodies in 36.84% (21/57; 95% CI: 24.32-49.36) of samples, while ELISA identified 42.11% (24/57; 95% CI: 29.29-54.92). IHA failed to detect any positive samples (0%). MAT and ELISA showed almost perfect agreement (κ = 0.817; 95% CI: 0.66-0.97) with no significant difference (p > 0.05). Compared to MAT, ELISA exhibited 95.2% sensitivity and 88.9% specificity. The combined MAT/ELISA approach with retesting of discordant samples yielded a final seroprevalence of 35.09% (20/57), with 8.77% (5/57) indeterminate results. MAT and ELISA are reliable methods for serological surveillance of T. gondii in red pandas, while IHA is unsuitable. We recommend MAT for initial screening followed by ELISA confirmation. The high seroprevalence highlights the need for integrated control strategies, including management of stray felids and rodents in captive environments to reduce transmission risks.