Limited value of cerebrospinal fluid for direct detection of Toxoplasma gondii in toxoplasmic encephalitis associated with AIDS.

The diagnosis of acquired immunodeficiency syndrome-associated toxoplasmic encephalitis (TE), a typically focal disease resulting from reactivation of tissue cysts, relies mainly on indirect diagnostic methods. In a prospective study, we investigated the value of detection of Toxoplasma gondii in cerebrospinal fluid (CSF) by using the polymerase chain reaction and the mouse inoculation test. Twenty-four patients with 26 episodes of TE, 2 HIV-infected patients with primary acute Toxoplasma infection, and 38 HIV-infected control patients with latent Toxoplasma infection were investigated. Detection of T. gondii in CSF by both methods was possible in only 3 of the TE patients (11.5%), the remaining patients being negative with either of the methods. In contrast, T. gondii DNA was detected in both of the acutely infected patients, indicating that in primary acute toxoplasmosis parasites may easily be found in the CSF, whereas in the majority of TE cases in immunocompromised patients, T. gondii parasites do not gain access to the CSF drawn by lumbar puncture.