Discontinuation of primary and secondary Toxoplasma gondii prophylaxis is safe in HIV-infected patients after immunological restoration with highly active antiretroviral therapy: results of an open, randomized, multicenter clinical trial.

Background: To our knowledge, no randomized trials have evaluated whether prophylaxis against toxoplasmic encephalitis can be safely discontinued after the CD4+ T cell count increases in response to highly active antiretroviral therapy.

Methods: We conducted a randomized, nonblinded, multicenter clinical trial of the discontinuation of primary or secondary prophylaxis against toxoplasmic encephalitis in human immunodeficiency virus (HIV)-infected patients with a sustained response to antiretroviral therapy (defined as a CD4+ T cell count of > or =200 cells/mm3 and a plasma HIV type 1 [HIV-1] RNA level of <5000 copies/mL for at least 3 months). Prophylaxis was restarted if the CD4+ T cell count decreased to <200 cells/mm3.

Results: The 381 patients receiving primary prophylaxis had a median CD4+ T cell count on study entry of 343 cells/mm3, and 318 (83%) of 381 patients had undetectable HIV-1 RNA in plasma. After a median follow-up period of 25 months (409 person-years), there were no episodes of toxoplasmic encephalitis among the 196 patients who discontinued prophylaxis (at 1 year, the upper limit of the 95% confidence interval for relapse rate was 2.40%). For the 57 patients receiving secondary prophylaxis, the median CD4+ T cell count on entry was 407 cells/mm3, and 49 (86%) of 57 patients had undetectable HIV-1 RNA in plasma. After a median follow-up period of 30.5 months (69 person-years), there were no episodes of toxoplasmic encephalitis among the 28 patients who discontinued prophylaxis (at 1 year, the upper limit of the 95% confidence interval for relapse rate was 16%).

Conclusions: In HIV-infected adult patients receiving effective highly active antiretroviral therapy, primary and secondary prophylaxis against toxoplasmic encephalitis can be safely discontinued after the CD4+ T cell count has increased to > or =200 cells/mm3 for >3 months.