First isolate of Toxoplasma gondii from arctic fox (Vulpes lagopus) from Svalbard

Cats are considered essential for the maintenance of Toxoplasma gondii in nature. However, T. gondii infection has been reported in arctic fox (Vulpes lagopus) from the Svalbard high arctic archipelago where felids are virtually absent. To identify the potential source of T. gondii, we attempted to isolate and genetically characterize the parasite from arctic foxes in Svalbard. Eleven foxes were trapped live in Grumant (78°11′N, 15°09′E), Svalbard, in September 2005 and 2006. One of the foxes was found to be seropositive to T. gondii by the modified agglutination test (MAT). The fox was euthanized and its heart and brain were bioassayed in mice for the isolation of T. gondii. All 10 mice inoculated with brain tissue and one of the five inoculated with heart developed MAT antibodies, and tissue cysts were found in the brains of seropositive mice. Two cats fed tissues from infected mice shed T. gondii oocysts. Genotyping using 10 PCR-RFLP markers and DNA sequencing of gene loci BSR4, GRA6, UPRT1 and UPRT2 determined the isolate to be Type II strain, the predominant T. gondii lineage in the world.