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Life Cycle T. gondii
  • "Members of the cat family (Felidae) are the only known definitive hosts for the sexual stages of T. gondii and thus are the main reservoirs of infection. 

  • Cats become infected with T. gondii by carnivorism. 

  • After tissue cysts or oocysts are ingested by the cat, viable organisms are released and invade epithelial cells of the small intestine where they undergo an asexual followed by a sexual cycle and then form oocysts, which are then excreted. 

  • The unsporulated oocyst takes 1 to 5 days after excretion to sporulate (become infective). 

  • Although cats shed oocysts for only 1 to 2 weeks, large numbers may be shed. 

  • Oocysts can survive in the environment for several months and are remarkably resistant to disinfectants, freezing, and drying, but are killed by heating to 70oC for 10 minutes.

  • Human infection may be acquired in several ways:

    • 1) Ingestion of undercooked infected meat containing Toxoplasma cysts;

    • 2) Ingestion of the oocyst from fecally contaminated hands or food;

    • 3) Organ transplantation or blood transfusion;

    • 4) Transplacental transmission;

    • 5) Accidental inoculation of tachyzoites. 

    • The parasites form tissue cysts, most commonly in skeletal muscle, myocardium, and brain; these cysts may remain throughout the life of the host."- CDC (used with permission, public domain)

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