Validating a point-of-care test for Toxoplasma gondii infection in southern sea otters (Enhydra lutris nereis).

Toxoplasma gondii is a zoonotic protozoan parasite that infects a high proportion of threatened southern sea otters (Enhydra lutris nereis) and is an important cause of mortality in this host species. Recently, a point-of-care rapid antibody test (POCT) for T. gondii infection was developed for detection of IgG and IgM antibodies in human sera. We aimed to validate the POCT using southern sea otter sera against a gold standard state of infection, based on histopathology, immunohistochemistry, parasite isolation, and PCR. In this study, we hypothesized that the POCT rapid screening tool would offer both high sensitivity and specificity (> 90%) for screening T. gondii infection in archived serum samples from southern sea otters with known T. gondii infection status. We applied the POCT assay to sera from 109 sea otters (49 negative, 60 positive), and this assay demonstrated an overall sensitivity of 93.3% and specificity of 93.9%. These results indicate that the POCT may be a useful screening tool for T. gondii exposure in sea otters. Utilization of this test in wildlife rehabilitation centers would allow for rapid, on-site, and cost-efficient screening of T. gondii exposure that could aid in the diagnosis and clinical management of sea otters with suspected toxoplasmosis. Future efforts could target POCT validation in species such as Hawaiian monk seals and Hector's dolphins, for which T. gondii is listed as a threat to species survival.