Cytologic detection of Toxoplasma gondii tachyzoites in cerebrospinal fluid.

We reviewed our case records to see how often Toxoplasma gondii organisms were identified by cytologic evaluation of cerebrospinal fluid (CSF). During a 12-year period, 6,090 CSF specimens were examined, and 2 cases (0.03%) showed tachyzoites. Both patients were immunocompromised. One patient underwent lumbar and ventricular taps, and the other underwent only ventricular tap. Organisms were identified in the ventricular specimens but not in the lumbar sample. Both patients were treated, and subsequent ventricular CSF samples were negative. Toxoplasma gondii can be identified by cytologic examination of CSF. Our results confirm prior observations that in patients with obstructive hydrocephalus, tachyzoites are more likely to be found in ventricular rather than lumbar specimens.