Toxoplasma gondii has very low host specificity, and it will probably infect almost any mammal. It has also been reported from birds, and has been found in virtually every country of the world.
Like most of the Apicomplexa, Toxoplasma is an obligate intracellular parasite.
Its life cycle includes two phases called the intestinal (or enteroepithelial) and extraintestinal phases.
The intestinal phase occurs in cats only (wild as well as domesticated cats) and produces "oocysts." The extraintestinal phase occurs in all infected animals (including cats) and produces "tachyzoites" and, eventually, "bradyzoites" or "zoitocysts."
The disease toxoplasmosis can be transmitted by ingestion of oocysts (in cat feces) or bradyzoites (in raw or undercooked meat).
In most humans infected with Toxoplasma, the disease is asymptomatic. However, under some conditions, toxoplasmosis can cause serious pathology, including hepatitis, pneumonia, blindness, and severe neurological disorders. This is especially true in individuals whose immune systems are compromised (e.g., AIDS patients).
Toxoplasmosis can also be transmitted transplacentally resulting in a spontaneous abortion, a still born, or a child that is severely handicapped mentally and/or physically.