Unpasteurized milk and unpasteurized dairy products. Fecally contaminated cat litter. Soil contaminated with cat feces. Toxoplasmosis is a disease caused by a parasitic protozoa, Toxoplasma gondii , which is a single cell organism which lives in, and gets its nutrients, from other animals. Most outdoor cats become infected with Toxoplasma soon after they are weaned by eating a wild bird or rodent that has been infected with Toxoplasma .
Cats shed oocysts in their feces for only a few weeks after the time of initial infection.
Oocysts can survive in soil and water for many months and can be found in gardens, playgrounds, barns, stables, or anywhere else that cats roam. Oocysts slowly die at below-freezing temperatures. Toxoplasma also can infect some food animals including pigs, sheep, goats, and cows. Raw or undercooked meat or unpasteurized milk from infected animals may contain pseudocysts, which are infectious for humans. One research study suggests that undercooked ground pork is a primary risk factor for toxoplasmosis.