ORGANISM 4--Toxoplasma gondii
COMMON NAME: None.
GEOGRAPHICAL DISTRIBUTION: Worldwide.
PATHOGENESIS: 30 to 90 percent human infection; acquired: asymptomatic, rarely a
severe systemic disease; congenital: acute or chronic; implicated as one of the
leading causes of birth defects; primarily diagnosed serologically.
HABITAT: Intracellular parasite; infects any nucleated cell of the body; intestinal
epithelium (initially) in felines only: predominance in brain and retina.
INTERMEDIATE HOST: Humans and many other mammals; cats and other felines are
RESERVOIR HOST: Cats and other domestic animals (reservoirs for human infection).
INFECTIVE FORM: Infective oocysts from cat feces; or tissue trophozoites or cysts.
MODE OF INFECTION: Ingestion of oocysts; spread by the blood; placental
penetration; ingestion of raw or poorly cooked meat.
SPECIMEN OF CHOICE: Blood, tissue biopsy.
Figure 2-11. Life cycle of Toxoplasma gondii.