T. gondii is a protozoan parasite
that infects humans and other warm-blooded animals. It is found wordwide.
Felines are the only definitive hosts of the organism. Both wild and domestic
cats serve as the main reservoir of infection. T. gondii is transmitted by
consumption of infectious oocysts in cat feces, consumption of tissue cysts in infected
meat, and by transplacental transfer of tachyzoites form mother to fetus.
Diagnosis is made by biologic, serologic, histologic methods, or a combination of
methods. Clinical signs of toxoplasmosis are nonspecific and are not sufficiently
characteristic for a definite diagnosis. Antemortem diagnosis may be accomplished
by indirect hemagglutination assay, indirect fluorescent antibody assay, latex agglutination
assay, or (ELISA). IgM antibodies appear sooner after infection than IgG antibodies,
however, they do not persist past 3 months after infection. Increased IgM
titers (>1:256) are consistent with recent infection. IgG antibodies appear
by the fourth week after infection and may remain increased for years during subclinical
infection.
