(Here's one of the diseases cats can expose you and your family to.)
Toxoplasmosis is a disease of humans and animals caused by the protozoan parasite Toxoplasma gondii. The biology of T. gondii is complicated, but it is important to know that the life cycle of the parasite begins with felids (cats, both wild and domestic).
Only felids can shed the infective form (oocyst) of the parasite in their fecal material. Humans and other types of animals become infected when inadvertently ingesting this infective oocyst through contact with cat fecal material. In the case of humans this contact might be intiated by cleaning cat litter boxes, gardening where cats defecate or playing in a sandbox in which a cat has defecated.
Toxoplasmosis causes a variety of disease syndromes in humans, ranging from flu-like symptoms in immunocompetant adults, to severe disseminated disease in immunosuppressed individuals, to birth defects in infants when women are exposed during pregnancy. Knowledge of the parasite and its life cycle is important to individuals with potential exposure to the many species affected by this organism.