Toxoplasmosis and HIV: a declining opportunistic disease with ongoing clinical significance

Abstract

Toxoplasma gondii infection is usually asymptomatic or mild in immunocompetent individuals, but it can cause substantial morbidity and mortality in patients with advanced immunosuppression, particularly those living with HIV infection. Historically, cerebral toxoplasmosis was one of the most frequent and severe opportunistic infections associated with AIDS. However, the introduction of highly effective antiretroviral therapy, early diagnosis of HIV infection, and the implementation of preventive measures have substantially reduced its epidemiological impact. Most cases result from the reactivation of a latent infection in patients with low CD4+ T-cell counts, with toxoplasmic encephalitis being the most common clinical manifestation. Diagnosis is primarily based on neuroimaging techniques, complemented in selected cases by microbiological methods. Prophylaxis with trimethoprim-sulfamethoxazole and early access to antiretroviral therapy have been essential in reducing disease incidence and preventing relapses. In Spain, cerebral toxoplasmosis has shown a marked decline since the 1990s, accompanied by a sustained reduction in hospitalizations and associated mortality. Nevertheless, it remains one of the most frequent AIDS-defining conditions (ADCs) and continues to represent an important clinical challenge among patients with late HIV diagnosis or insufficient access to healthcare. Maintaining early HIV diagnosis, universal access to antiretroviral treatment, and effective preventive strategies remains essential to consolidate the progress achieved.