Toxoplasmosis of the central nervous system in patients with AIDS in Mexico

Toxoplasmosis of the central nervous system (CNS) is the most common cause of intracerebral lesions in patients with AIDS. It is now standard clinical practice to treat empirically, based on clinical and radiographic findings, and to perform a biopsy of the lesion only in those patients who fail to have a clinical and radiographic response after two weeks of therapy. This study describes the presentation and response to therapy of central nervous system toxoplasmosis in patients with AIDS at a private practice in Mexico City. A retrospective chart and radiology review of all patients with AIDS treated empirically for toxoplasmosis between 1988 and 1993 was performed. A total of 177 patients with AIDS were seen, nine (5.1%) had toxoplasmosis. Patients with toxoplasmosis were males with a median age of 39 years (range 26 - 65). In two patients, toxoplamosis of the CNS was the initial manifestation of HIV infection, all others had a prior diagnosis of AIDS with a mean of 10 months between their first AIDS defining event and the diagnosis of toxoplasmosis. The median CD4+ T-cell count at the time of the diagnosis of toxoplamsosis was 78 cells/microL. Most patients had headache associated with other focal neurological symptoms such as hemiplegia (2), hemiparesis (2) or seizures (4). Only 4 out of 9 patients had fever as part of their initial clinical presentation. Serum IgG antibodies against Toxoplasma gondii were positive in 6 out of 7 patients tested, while IgM antibodies were negative in all patients. On imaging studies (Computerized Tomography or Magnetic Resonance Imaging), 4 patients had a single lesion while the rest had two or more lesions. Two patients were initially treated with pyrimethamine/sulfadiazine and were later changed to pyrimethamine/clindamycin, which was the treatment given from the beginning to all other patients. One patient died of an intralesional hemorrhage two weeks after the diagnosis despite adequate therapy. The probability of surviving 6 months after the diagnosis of toxoplasmosis was 60%. The findings of these authors are similar to those reported in other series where toxoplasmosis of the CNS is a late complication of HIV infection associated with a CD4+ cell count of < 100 cells/microL. However, survival was short in spite of a good response to therapy.