Toxoplasmosis in HIV/AIDS: a living legacy

Toxoplasmosis has historically been considered one of the most important opportunistic infections detected in HIV/AIDS patients. The prevalence rates of latent Toxoplasma infections in HIV-infected patients has been found to vary greatly from 3% to 97%. Prevalence has been found to be related to ethnicity, certain risk factors, and reactivation of toxoplasmosis. Prior to antiretroviral therapy, toxoplasmic encephalitis (TE) was the most common focal cerebral lesion detected in AIDS patients with Toxoplasma infection, occurring in approximately half of Toxoplasma-seropositive patients. Other forms of dissemination have also been reported in AIDS patients in sites such as the eyes, lungs, heart and spinal cord. Anti-Toxoplasma therapy and chemoprophylaxis have shown effectiveness in reducing the incidence of TE, while noncompliance has been identified as a cause of relapse in these settings. Toxoplasmosis is one of the most common neuropathological complications found at autopsy. Rapid progress in the development of highly active antiretroviral therapy (HAART) has changed the observed patterns with TE, for which there has been a marked decrease in overall incidence. Subsequently, TE has been found to be significantly associated with the so-called "neurological immune restoration inflammatory syndrome" (NIRIS). Toxoplasma screening programs are recommended for all newly diagnosed HIV-positive patients. Chemoprophylaxis should be considered in HIV-infected patients who have a CD4 < 200 cells/mm3, particularly in settings where resources are limited and there is not access to HAART. TE remains a cause of morbidity and mortality among AIDS patients.