Epidemiologic observations on infection with Toxoplasma gondii in three species of urban mammals from Baltimore, Maryland, USA.

The prevalence of antibodies to Toxoplasma gondii was determined in three species of domestic and commensal mammals, from Baltimore, Maryland, USA. Crude prevalences of infection were 14.5% in cats (N = 650), 32.2% in dogs (N = 233), and 49.5% in Norway rats (N = 109). Oocysts identical to T. gondii were detected in 0.5% of cat feces. Cats and rats showed antibody prevalence rates which were strongly age-(or some age-related variable) dependent, with the highest rates associated with older animals. Antibody prevalence increased in dogs up to three years of age, then declined slightly in older animals.