Seroprevalence and Risk Factors for Toxoplasma gondii Infection in Owned Domestic Cats in Australia.

Ongoing surveillance of Toxoplasma gondii seroprevalence and exposure risks in owned cats is important to identify effective mechanisms to decrease the prevalence of this global zoonotic parasite. We aimed to determine the seroprevalence of T. gondii and risk factors for seropositivity in owned domestic cats in Australia. Sera, signalment data, postcode, and completed owner-questionnaires surveying diet composition and lifestyle factors were collected for cats presenting to 18 veterinary clinics across Australia. T. gondii-specific IgG was measured by enzyme-linked immunosorbent assay. Data were analyzed using univariable and multivariable logistic regression to evaluate risk factors associated with positive T. gondii IgG serology. Among 417 cats, T. gondii seroprevalence was 39%. More than two-thirds of cats tested (69%) had outdoor access and 59% were fed a diet containing raw meat. Univariable analyses identified, age (>1 year, p < 0.001), a diet containing any raw meat (p = 0.001), raw kangaroo (p = 0.008), raw chicken (p = 0.012), or raw beef (p = 0.017), and hunting (p = 0.049) as risk factors for T. gondii infection. Age (>1 year, odds ratio [OR]: 7.15) and feeding of raw meat (OR: 2.23) remained significant risk factors (p < 0.001) in multivariable analyses. T. gondii seroprevalence did not differ between cats domiciled in urban and semiurban or rural areas. Pet cats in Australia are commonly infected with T. gondii. Feeding raw meat to cats, a common practice in Australia, is associated with T. gondii infection, highlighting the need for education about the health implications for cats from feeding a diet containing raw meat.

Comparison of genotypes of Toxoplasma gondii in domestic cats from Australia with latent infection or clinical toxoplasmosis.

Whether Toxoplasma gondii genotype is associated with disease severity in naturally occurring toxoplasmosis in domestic cats is unknown. The aim of this study was to compare genotypes of T. gondii in latently infected cats with those in cats with clinical toxoplasmosis. Results of a PCR targeting the B1 gene to detect T. gondii DNA were positive in tissue samples from 11 of 17 (65%) seropositive cats tested including four with clinical toxoplasmosis and seven with latent infections, as determined by serology, histologic findings and immunohistochemistry. Three of the four cats with clinical toxoplasmosis were immunosuppressed. Complete genotyping was performed in seven cats using PCR-RFLP at 12 loci (SAG1, 5'SAG2 and 3'SAG2, altSAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 and Apico) and direct sequencing of the multi-copy B1 gene. Partial genotyping using six loci was performed in one cat with latent infection. T. gondii type II (ToxoDB genotype #3) was determined in four cats with clinical toxoplasmosis and three cats with latent toxoplasmosis Novel T. gondii B1 gene polymorphisms were detected in two strains (at nucleotide posititions 233, 366 and 595) and a B1 gene polymorphism unique to Australia was identified in another (guanine/adenine at nucleotide position 378). One cat was co-infected with two or more type-II like strains at 3'SAG2. The results of this study suggest that the infecting T. gondii genotype, based on these 12 loci, is not a determinant of clinical disease in cats naturally infected with T. gondii and type II strains are prevalent in Australia.