Clinical features, outcome and survival from cerebral toxoplasmosis in Edinburgh AIDS patients

Nineteen cases of cerebral toxoplasmosis (CTOX) are reported from a group of Edinburgh AIDS patients. All patients were severely immunodeficient at the time of presentation with CD4 count < 50 cells/mm3. Thirteen patients had suffered a previous AIDS-defining illness. In Edinburgh, CTOX has developed in 48% of patients who are seropositive for toxoplasma and have a CD4 count < 50 cells/mm3. It is estimated that at least half of the toxoplasma seropositive patients will develop CTOX if they survive for 21 months after reaching a time in their illness when the CD4 count = 50 cells/mm3. The incidence of CTOX in toxoplasma-seronegative patients with a CD4 count < 50 cells/mm3 is 1.3%. All patients showed improvement on treatment and there was no correlation between clinical or radiological features and patient survival. Those patients unable to tolerate first choice anti-toxoplasma therapy had a significantly shorter survival than the remainder but there was no single therapeutic regimen which conferred a survival advantage. Eighteen patients had died at the time of study and the median survival following diagnosis of cerebral toxoplasmosis was 10 months (range 3-38 months). Postmortem examination of the brain was available in 8, 4 of whom had concomitant cerebral lymphoma. The survival from AIDS or CD4 count = 50 cells/mm3 did not differ significantly between those with treated CTOX and a control group who had no toxoplasma infection, suggesting that treatment is reasonably effective. CTOX is a disease associated with severe HIV-related immunodeficiency and, in those with a CD4 count < 50 cells/mm3, occurs more than 35 times as frequently in toxoplasma-seropositive than toxoplasma-seronegative patients. Treatment is effective but the outcome of treated disease cannot be predicted from presenting clinical or radiological features. Concomitant space-occupying cerebral pathology is evident in 50% of post-mortem examinations.