You will need to test for cat feces to collect oocytes, and you will need to look for it in the muscles of the intermediate hosts or the mouse brain to collect the bradyzoites.
Contact with cats or their excretions. Wheelchair users are at particular risk, as, by touching the wheels, they always have indirect contact with potentially contaminated soil. The parasites you can purchase from ATTC (https://www.atcc.org/). (https://www.atcc.org/search#q=toxoplasma&sort=relevancy&numberOfResults=24)