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Microbiology and Epidemiology
Toxoplasmosis is caused by the intracellular parasite Toxoplasma gondii; cats and their prey are the definitive hosts. The primary route of transmission to humans is ingestion of tissue cysts from soil, food (e.g., undercooked meat), or water contaminated by cat feces.
- Roughly one-third of women who contract T. gondii during pregnancy transmit the parasite to the fetus, with a 65% risk of transmission if maternal infection is acquired in the third trimester.
- In the United States and most European countries, seroconversion rates increase with age and exposure; 10–67% of persons >50 years old are seropositive.