Seroprevalence of Toxoplasma gondii in mainland and sub-Antarctic New Zealand sea lion (Phocarctos hookeri) populations

Toxoplasma gondii infection is unlikely to be a major contributor to reproductive failure in New Zealand sea lions (Phocarctos hookeri), according to a study analyzing seroprevalence across mainland and sub-Antarctic populations. The research tested archived sera from 55 sea lions using ELISA, latex agglutination tests (LAT), and Western blot validation, revealing five positive cases—all from mainland locations (Otago Peninsula and Stewart Island). Notably, two adult females exhibited high antibody titres over consecutive years, while no sub-Antarctic Enderby Island sea lions tested positive. While T. gondii does not appear to significantly impact reproduction in these threatened populations, the study underscores the need for ongoing surveillance to assess potential subclinical effects. The findings also suggest that commercially available tests, with species-specific threshold adjustments, could serve as a reliable and cost-effective tool for monitoring exposure in New Zealand sea lions.

Michael, S., Howe, L., Chilvers, B., Morel, P., & Roe, W. (2016). Seroprevalence of Toxoplasma gondii in mainland and sub-Antarctic New Zealand sea lion (Phocarctos hookeri) populations. New Zealand Veterinary Journal, 64(5), 293–297. https://doi.org/10.1080/00480169.2016.1191974