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

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


AIMS: To investigate the seroprevalence of antibodies to Toxoplasma gondii in New Zealand sea lions (Phocarctos hookeri), as a potential contributor to reproductive failure.

METHODS: Archived sera were sourced from New Zealand sea lions from two recolonising mainland populations in the Otago Peninsula (n=15) and Stewart Island (n=12), as well as a declining population at Enderby Island (n=28) in the New Zealand sub-Antarctic. Sera were tested for antibodies to T. gondii using a commercially available ELISA (with samples considered positive if the sample to positive ratio was >30%), and latex agglutination test (LAT; with titres ≥1:32 considered positive). Western blot analysis was used to validate the results of a subset of 14 samples.

RESULTS: Five samples from sea lions in mainland locations were confirmed positive for antibodies to T. gondii. Two adult females exhibited high LAT antibody titres (min 1:2048, max 1:4096) on both occasions when sampled 1 and 2 years apart, respectively. No animals from Enderby Island were seropositive.

CONCLUSIONS: Toxoplasma gondii infection is unlikely to be a major contributor to poor reproductive success in New Zealand sea lions. However, continued surveillance is pertinent to assess subclinical and clinical impacts of the parasite on these threatened populations. The commercial tests evaluated here, with further species-specific threshold refinement could provide a fast, inexpensive and reliable indicator of T. gondii exposure in New Zealand sea lions.

KEY WORDS: ELISA, latex agglutination test, Phocarctos hookeri, pinniped, Toxoplasma gondii, western blot

Access to the full text of this article is available:

through another providers website:

If you're a member or subscriber and believe you should have access:



Register for an account

Request new password

The whole of the literary matter of the New Zealand Veterinary Journal is copyright Taylor and Francis, Downloading this article signifies agreement with the terms and conditions of electronic access.