Risk factors for toxoplasmic encephalitis in HIV-infected patients: a case-control study in Brazil

A case-control study to identify the risk factors for toxoplasmic encephali tis (TE) among HIV-infected patients with latent Toxoplasma gondii infectio n was performed in a teaching hospital in south-eastern Brazil. Although th e subjects were all positive for serum IgG antibodies to Toxoplasma, some ( the cases) developed TE during routine follow-up at the hospital whereas ot hers (the controls) did not. Adjusted odds ratios (aOR) were estimated by m ultiple logistic regression after controlling for potential confounders. On ly 46 (22%) of the 210 cases but 93 (45%) of the 205 controls were on proph ylactic regimens with co-trimoxazole [aOR = 0.30; 95% confidence interval ( CI) = 0.15-0.60]. Subjects with fewer than 100 (aOR = 37.09; CI = 7.49-183. 67) or between 100 and 200 CD4 cells/mul (aOR = 10.20; CI = 2.00-51.90) wer e at substantially increased risk of developing TE than those with >400 CD4 cells/mul. Although the results of preliminary, unadjusted data analysis i ndicated that male sex and homosexual or bisexual activity might be additio nal risk factors, these associations were not found to be statistically sig nificant by multiple regression analysis. In conclusion, no risk factors fo r TE other than low CD4 cell counts and failure to receive prophylaxis were found among HIV-infected Brazilian patients with past exposure to Toxoplas ma. Seropositive patients with CD4 cell counts above 100/mul (the point at which specific prophylaxis is usually recommended) but below 200/mul might also benefit from effective anti-TE prophylaxis.