Serological and molecular detection of Toxoplasma gondii in naturally infected red foxes (Vulpes vulpes) from Victoria, Australia

Toxoplasma gondii is a zoonotic parasite with a global distribution that can infect a wide range of warm-blooded hosts. This study investigated, for the first time, the seroprevalence and genetic variability of T. gondii in red foxes (Vulpes vulpes) from Victoria, Australia. Animals from both regional Victoria and the metropolitan Melbourne area were sourced from trappers and shooters involved in pest control. Sera were screened for anti-T. gondii IgG antibodies using a modified agglutination test, and tissue samples were tested using a qPCR assay targeting the 529 bp repeated element. qPCR positive samples were genotyped using a five-marker (L358, 5'SAG2, 3'SAG2, c22-8, GRA6) polymerase chain reaction-restriction fragment length polymorphism protocol. Anti-T. gondii antibodies were detected in 38.9% (30/77) of foxes, and parasite DNA was identified in 23.4% (18/77) of animals. Genotyping revealed a predominance of T. gondii clonal Type II whereas two isolates showed new alleles attributable to Type II-like genotypes. These findings suggest that Australian red foxes are frequently exposed to T. gondii and may play an important role as epidemiological sentinels to assess the circulation of T. gondii in the Australian environment, with implications for both wildlife conservation and public health.