Cerebral Toxoplasmosis

The choice of drugs for treating cerebral toxoplasmosis is limited. There are only three drugs available, and, of these, pyrimethamine and sulfonamide are invariably used in combination. Clindamycin is an alternative choice. Another drug, spiramycin, has poor central nervous system penetration, but achieves high concentrations in the placenta, and it is useful for treatment of toxoplasmosis during pregnancy. Because long-term maintenance therapy is often necessary, particularly in patients with AIDS, a wider choice of antibiotics is urgently necessary, because of potential problems with drug resistance and side effects. Treatment may be started empirically in any patient with HIV infection and multiple brain lesions. The drugs of choice are a combination of sulfadiazine and pyrimethamine. Folinic acid should be added to prevent pyrimethamine-induced bone marrow suppression. Repeated neuroimaging, 2 weeks after initiating therapy, is needed to assess efficacy of treatment. If CD4 cell counts remain below 100 cells per mm(3), lifelong therapy is needed. Tissue diagnosis should be established in patients who do not respond to treatment, who have solitary lesions, or in patients without AIDS. Recent breakthroughs in the understanding of the biology of Toxoplasma will result in the development of a range of new therapies in the near future.